Blowoff valve

A blowoff valve is a pressure release system present in turbocharged engines, its purpose is to prevent compressor surge and reduce wear on the engine.


Definitions

A compressor bypass valve (CBV) also known as a compressor relief valve is a vacuum-actuated valve designed to release pressure in the intake system of a turbocharged or centrifugally supercharged car when the throttle is lifted or closed. This air pressure is re-circulated back into the non-pressurized end of the intake (before the turbo) but after the mass airflow sensor.

A blowoff valve, (BOV, sometimes hooter valve, dump valve) does basically the same thing, but releases the air to the atmosphere. This creates a very distinctive sound desired by many who own turbocharged sports cars. Some blowoff valves are sold with trumpet shaped exits that amplify the "Psshhhh" sound, these designs are normally marketed towards the keen boy racer. For some owners this is the only reason to fit a BOV. Motor sports governed by the FIA have made it illegal to vent unmuffled blowoff valves to the atmosphere. In the United States, Australia and Europe cars featuring unmuffled blowoff valves are illegal for street use.



Downsides of releasing air to atmosphere

This unique sound sometimes comes at a price. On a car with a mass airflow sensor, doing this confuses the engine control unit (ECU) of the car. The ECU is told it has a specific amount of air in the intake system, and injects fuel accordingly. The amount of air released by the blowoff valve is not taken into consideration and the engine runs rich for a period of time.*

Typically this isn't a major issue, but sometimes it can lead to hesitation or stalling of the engine when the throttle is closed. This situation worsens with higher boost pressures. Eventually this can foul spark plugs and destroy the catalytic converter (when running rich, not all the fuel is burned which can heat up on and melt the converter).

* Note that engines using a MAP (manifold absolute pressure) system are not affected.


Purpose of Relief and Blow Off Valves

Blowoff valves are used to prevent compressor surge. Compressor surge is a phenomenon that occurs when lifting off the throttle of a turbocharged car (with a non-existent or faulty bypass valve). When the throttle plate on a turbocharged engine running boost closes, high pressure in the intake system has nowhere to go. It is forced to travel back to the turbocharger in the form of a pressure wave. This results in the wheel rapidly decreasing speed and stalling. The driver will notice a fluttering air sound. In extreme cases the compressor wheel will stop completely or even go backwards. Compressor surge is very hard on the bearings in the turbocharger and can significantly decrease its lifespan. In addition, the now slower moving compressor wheel takes longer to spool (speed up) when throttle is applied. This is known as turbo lag.

With the implementation of either a bypass valve or a blowoff valve the pressurized air escapes, allowing the turbo to continue spinning. This allows the turbocharger to have less turbo lag when power is demanded next.



How it works




A blow-off-valve is connected by a vacuum hose to the intake manifold after the throttle plate. When the throttle is closed, underpressure develops in the intake manifold after the throttle plate and "sucks" the blowoff valve open. The excess pressure from the turbocharger is vented into the atmosphere or recirculated into the intake upstream of the compressor inlet.



Tuning adjustable valves

Most aftermarket valves are adjustable leaving customers curious on how to set them properly for their vehicle. Typically the adjustment lies in the spring preload. Here is how to set it.

You want the spring as soft as possible without leaking boost at peak pressure. If the spring is set too soft then the valve will not close fully resulting in a boost leak and idle problems. If you set it too hard then the valve will not fully open, close too early, and have compressor surge.

Trial and error with an accurate boost gauge is the perfect way to find the right setting for your vehicle....

Intercooler

An intercooler, or charge air cooler, is a device used on turbocharged and supercharged internal combustion engines to improve their volumetric efficiency by increasing the amount of charge in the engine and lowering charge air temperature thereby increasing power and reliability. It is also known as a charge air cooler, especially on larger engines that may easily self-destruct with high intake-air temperatures. The inter in the name refers to its location compared to the compressors; the coolers were typically installed between multiple stages of supercharging in aircraft engines. Modern automobile designs are technically aftercoolers because they appear most often at the very end of the chain, but this term is no longer used.


Turbocharging

Turbochargers and superchargers compress incoming air, causing it to become heated (see the ideal gas law). Since hot air is less dense than cooler air at the same pressure, the total charge delivered to the cylinders is higher than non-compressed air but still less than it could be. By cooling the charge after compression, the stream experiences further compression which is naturally tied with cooling of matter—upon cooling matter shrinks occupying less volume (usually, see Coefficient of Thermal Expansion). With this further compression even more charge can be delivered, increasing power. Additionally, intercoolers help to increase the total amount of boost possible without causing engine knocking. One of the most efficient intercoolers is water injection—it cools the intake charge and cools down the combustion temperature.

An intercooler or charge air cooler is essentially a radiator tuned for high volume flow rates and the increasing density of the charge as it cools. Most designs use ambient air for cooling, flowing through the radiator core, and often co-located with other radiators for oil or cooling fluid. This approach is also known as Air To Air (ATA).



Charge Cooling

An alternate design, often referred to as a chargecooler charge cooler, (heat exchanger) uses water or a water/antifreeze mix to cool the charge, then cools the water in a separate radiator. While heavier and more complex, charge coolers can often make arranging the rest of the engine much simpler. This approach is also known as Water To Air (WTA or A/W). A variation on this type of charge cooler substitutes a reservoir of coolant for the radiator, allowing the use of an icewater mixture or liquid nitrogen that can bring outlet temperatures well below ambient air temperature even under very high boost pressure. Because of the limitations on the volume of coolant that can be stored and circulated, this approach to charge cooling is only practical for short durations, making it most common in drag racing and land speed record attempts.

In at least one land speed record attempt, Gale Banks used nitrous oxide, not internally as a power-adder, but as the medium into which the heat was transferred from the charge air. The nitrous oxide was held in bottles and released through the intercoolers' cooling fins and exhausted directly to the atmosphere. Extra cooling by nitrous oxide spraying on the front of the intercooler is now a related commercially available upgrade.

Extra cooling of the charge air can be achieved also by externally spraying water on the front of the intercooler. This can be activated automatically or manually, and is far cheaper to refill than nitrous oxide.

Air to air intercoolers need to be mounted so as to maximize air flow and promote efficient cooling. Most cars such as the Toyota Supra, Nissan Skyline, Saab (except the Subaru WRX-based 9-2X Aero), Dodge SRT-4, Mitsubishi Lancer Evolution, Volkswagen and Audi use front mounted intercooler(s) (FMIC) mounted vertically near the front bumper, in line with the car's radiator. Many older turbo-charged cars, such as the Saab 900, and Turbo Mitsubishi Eclipse use side-mounted intercoolers (SMIC), which are mounted in the front corner of a bumper, in front of one of the wheels. Side-mounted intercoolers are generally smaller and less efficient than front-mounted intercoolers. Cars such as the Subaru Impreza WRX, MINI Cooper S and the MAZDASPEED 6 use top mounted intercoolers (TMIC) which are mounted horizontally on top of the engine (due to a low hood line) and use a hood scoop to force air over the intercooler. Some World Rally Championship cars use a reverse-induction setup, where air from ducts in the front bumper is forced up over a horizontally-mounted intercooler and then vented through ducts in the top of the hood to further maximize aerodynamic benefits.

Homogeneous Charge Compression Ignition (HCCI)

Introduction

Homogeneous Charge Compression Ignition, or HCCI, is a form of internal combustion in which well mixed fuel and oxidizer (typically air) are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction releases chemical energy into a sensible form that can be translated by an engine into work and heat.

HCCI has characteristics from each of the two most popular forms of combustion used in IC engines: homogeneous charge spark ignition (gasoline engines) and stratified charge compression ignition (diesel engines). As in homogeneous charge spark ignition, the fuel and oxidizer are mixed together. However, rather than using an electric discharge to ignite a portion of the mixture, the concentration and temperature of the mixture are raised by compression until the entire mixture reacts simultaneously. Stratified charge compression ignition also relies on the heat and concentration resulting from compression, but combustion occurs at the boundary of unmixed fuel which is injected to initiate combustion.

The defining characteristic of HCCI is that the ignition occurs at several places at a time which makes the fuel/air mixture burn nearly simultaneously. There is no direct initiator of combustion. This makes the process inherently challenging to control. However, with advances in microprocessors and a physical understanding of the ignition process, HCCI can be controlled to achieve gasoline engine like emissions along with diesel engine like efficiency. In fact, HCCI engines have been shown to achieve extremely low levels of Nitrogen oxide emissions (NOx) without aftertreatment catalytic converter. The unburned hydrocarbon and carbon monoxide emissions are still high (due to lower peak temperatures), as in gasoline engines, and must still be treated to meet automotive emission regulations.



History

HCCI engines have a long history, even though HCCI has not been as widely implemented as spark ignition or diesel injection. It is essentially an Otto combustion cycle. In fact, HCCI was popular before electronic spark ignition was used. One example is the hot-bulb engine which used a torch-heated head to add heat to the inducted gases. The extra heat combined with compression induced the conditions for combustion to occur.


Operation


Methods

A mixture of fuel and air will ignite when the concentration and temperature of reactants is sufficiently high. The concentration and/or temperature can be increased several different ways:

* High compression ratio
* Pre-heat induction gases
* Forced induction
* Retain or reinduct exhaust

Once ignited, combustion occurs very quickly. When auto-ignition occurs too early or with too much chemical energy combustion is too fast. In such cases, high in-cylinder pressures can destroy an engine. For this reason, HCCI is typically operated at lean overall fuel mixtures.



Advantages

* HCCI is closer to the ideal Otto cycle than spark ignited combustion.

* Lean operation leads to higher efficiency than in spark ignited gasoline engines

* Homogeneous mixing of fuel and air leads to cleaner combustion and lower emissions. In fact, due to the fact that peak temperatures are significantly lower than in typical spark ignited engines, NOx levels are almost negligible.

* Since HCCI runs throttleless, it eliminates throttling losses



Disadvantages

* High peak pressures
* High heat release rates
* Difficulty of control
* Limited power range
* High carbon monoxide and hydrocarbon pre-catalyst emissions




Control

Controlling HCCI is a major hurdle to more widespread commercialization. HCCI is more difficult to control than other popular modern combustion methods.

In a typical gasoline engine, a spark is used to ignite the pre-mixed fuel and air. In diesel engines, combustion begins when the fuel is injected into compressed air. In both cases, the timing of combustion is explicitly controlled. In an HCCI engine, however, the homogeneous mixture of fuel and air is compressed, and combustion begins whenever the appropriate conditions are reached. This means that there is no well-defined combustion initiator that can be directly controlled. An engine can be designed so that the ignition conditions occur at a desirable timing. However, this would only happen at one operating point. The engine could not change the amount of work it produces. This could work in a hybrid vehicle, but most engines change their energy production to meet user demand.

To achieve dynamic operation in an HCCI engine, the control system must change the conditions that induce combustion. Thus, the engine must control either the compression ratio, inducted gas temperature, inducted gas pressure, or quantity of retained or reinducted exhaust.

Several approaches have been suggested for control



Variable compression ratio

There are several methods of modulating both the geometric and effective compression ratio. The geometric compression ratio can be changed with a movable plunger at the top of the cylinder head. The effective compression ratio can be reduced from the geometric ratio by closing the intake valve either very late or very early with some form of variable valve actuation. Both of the approaches mentioned above require large amounts of energy to achieve fast responses and are expensive.



Variable induction temperature

This technique is also known as fast thermal management. It is accomplished by rapidly varying the cycle to cycle intake charge temperature. It is also expensive to implement and has limited bandwidth associated with actuator energy.



Variable exhaust gas percentage

Exhaust gas can be very hot if retained or reinducted from the previous combustion cycle or cool if recirculated through the intake as in conventional EGR systems. The exhaust has dual effects on HCCI combustion. It dilutes the fresh charge, delaying ignition and reducing the chemical energy and engine work. Hot combustion products conversely will increase the temperature of the gases in the cylinder and advance ignition.



Variable valve actuation

Variable valve actuation allows control over the compression ratio and the exhaust gas percentage. However, fully variable valve actuation is complicated and the componentry is expensive.



High peak pressures and heat release rates

In a typical gasoline or diesel engine, combustion occurs via a flame. Hence at any point in time, only a fraction of the total fuel is burning. This results in low peak pressures and low energy release rates as fuel is burnt over a longer period of time. In HCCI, however, the entire fuel/air mixture ignites and burns nearly simultaneously resulting in high peak pressures and energy release rates. To withstand the higher pressures, the engine has to be structurally stronger, and that means heavier.

Several strategies have been proposed to lower the rate of combustion. Two different blends of fuel can be used. That way, the two fuels will ignite at different points of time resulting in lesser combustion speed. The problem with this idea is the requirement to set up an infrastructure to supply the blended fuel. Dillution, for example with exhaust, reduces the pressure and combustion rate at the cost of work production.



Power

In a gasoline engine, power can be increased by increasing the fuel/air charge. In a diesel engine, power can be increased by increasing the amount of fuel injected. The engines can withstand a boost in power because the heat release rate in these engines is slow. In HCCI however, the entire mixture burns nearly simultaneously. Increasing the fuel/air ratio will result in even higher peak pressures and heat release rates. Also, increasing the fuel/air ratio (also called the equivalence ratio) increases the danger of knock. In addition, many of the viable control strategies for HCCI require thermal preheating of the charge which reduces the density and hence the mass of the air/fuel charge in the combustion chamber, reducing power. These factors makes increasing the power in HCCI inherently challenging.

One way to increase power is to use different blends of fuel. This will lower the heat release rate and peak pressures and will make it possible to increase the equivalence ratio. Another way is to thermally stratify the charge so that different points in the compressed charge will have different temperatures and will burn at different times lowering the heat release rate making it possible to increase power. A third way is to run the engine in HCCI mode only at part load conditions and run it as a diesel or spark ignition engine at full or near full load conditions. Since much more research is required to successfully implement thermal stratification in the compressed charge, the last approach is being studied more intensively.


Carbon Monoxide and Hydrocarbon emissions

Since HCCI operates on lean mixtures, the peak temperatures are lower in comparison to spark ignition and diesel engines. The low peak temperatures prevent the formation of NOx. However they also lead to incomplete burning of fuel especially near the walls of the combustion chamber. This leads to high carbon monoxide and hydrocarbon emissions. An oxidizing catalyst would be effective at removing the regulated species since the exhaust is still oxygen rich.


Difference from Knock

Engine knock or pinging occurs when some of the unburnt gases ahead of the flame in a spark ignited engine spontaneously ignite. The unburnt gas ahead of the flame is compressed as the flame propagates and the pressure in the combustion chamber rises. The high pressure and corresponding high temperature of unburnt reactants can cause them to spontaneously ignite. This causes a shock wave to traverse from the end gas region and an expansion wave to traverse into the end gas region. The two waves reflect off the boundaries of the combustion chamber and interact to produce high amplitude standing waves.

A similar ignition process occurs in HCCI. However, rather than part of the reactant mixture being ignited by compression heating ahead of a flame front, ignition in HCCI engines occurs due to piston compression. In HCCI, the entire reactant mixture ignites (nearly) simultaneaously. Since there are very little or no pressure differences between the different regions of the gas, there is no shock wave propagation and hence no knocking. However at high loads (i.e. high fuel/air ratios), knocking is a possibility even in HCCI.

Stirling engine Applications

Combined heat and power applications

The principal use of Stirling engines today is as an economical source of electrical power often utilising a heat source from an industrial process. WhisperGen, a New Zealand firm with offices in Christchurch, has developed an "AC Micro Combined Heat and Power" stirling cycle engine. These microCHP units are gas-fired central heating boilers which sell power back into the electricity grid. WhisperGen announced in 2004 that they were producing 80,000 units for the residential market in the United Kingdom. A 20 unit trial in Germany started in 2006.


Solar power generation

Placed at the focus of a parabolic mirror a Stirling engine can convert solar energy to electricity with an efficiency better than photovoltaic cells. On August 11, 2005, Southern California Edison announced an agreement to purchase solar powered Stirling engines from Stirling Energy Systems[7] over a twenty year period and in quantity (20,000 units) sufficient to generate 500 megawatts of electricity. These systems, on a 4,500 acre (19 km²) solar farm, will use mirrors to direct and concentrate sunlight onto the engines which will in turn drive generators.


Stirling cryocoolers

Any Stirling engine will also work in reverse as a heat pump: i.e. when a motion is applied to the shaft, a temperature difference appears between the reservoirs. One of their modern uses is in refrigeration and cryogenics.

The essential mechanical components of a Stirling cryocooler are identical to a Stirling engine. The turning of the shaft will compress the working gas causing its temperature to rise. This heat will then be dissipated by pushing the gas against a heat exchanger. Heat would then flow from the gas into this heat exchanger which would probably be cooled by passing a flow of air or other fluid over its exterior. The further turning of the shaft will then expand the working gas. Since it had just been cooled the expansion will reduce its temperature even further. The now very cold gas will be pushed against the other heat exchanger and heat would flow from it into the gas. The external side of this heat exchanger would be inside a thermally insulated compartment such as a refrigerator. This cycle would be repeated once for each turn of the shaft. Heat is in effect pumped out of this compartment, through the working gas of the cryocooler and dumped into the environment. The temperature inside the compartment will drop because its insulation prevents ambient heat from coming in to replace that pumped out.

As with the Stirling engine, efficiency is improved by passing the gas through a “Regenerator” which buffers the flow of heat between the hot and cold ends of the gas chamber.

The first Stirling-cycle cryocooler was developed at Philips in the 1950s and commercialized in such places as liquid nitrogen production plants. The Philips Cryogenics business evolved until it was split off in 1990 to form the Stirling Cryogenics & Refrigeration BV, Stirling The Netherlands. This company is still active in the development and manufacturing Stirling cryocoolers and cryogenic cooling systems.

A wide variety of smaller size Stirling cryocoolers are commercially available for tasks such as the cooling of sensors.

Thermoacoustic refrigeration uses a Stirling cycle in a working gas which is created by high amplitude sound waves.


Heat pump

A Stirling heat pump is very similar to a Stirling cryocooler, the main difference being that it usually operates at room-temperature and its principal application to date is to pump heat from the outside of a building to the inside, thus cheaply heating it.

As with any other Stirling device, heat flows from the expansion space to the compression space; however, in contrast to the Stirling engine, the expansion space is at a lower temperature than the compression space, so instead of producing work, an input of mechanical work is required by the system (in order to satisfy the second law of thermodynamics). When the mechanical work for the heat-pump is provided by a second Stirling engine, then the overall system is called a "heat-driven, heat-pump".

The expansion-side of the heat-pump is thermally coupled to the heat-source, which is often the external environment. The compression side of the Stirling device is placed in the environment to be heated, for example a building, and heat is "pumped" into it. Typically there will be thermal insulation between the two sides so there will be a temperature rise inside the insulated space.

Heat-pumps are by far the most energy-efficient types of heating systems. Stirling heat-pumps also often have a higher coefficient of performance than conventional heat-pumps. To date, these systems have seen limited commercial use; however, use is expected to increase along with market demand for energy conservation, and adoption will likely be accelerated by technological refinements.


Marine engines

Kockums, the Swedish shipbuilder, had built at least 10 commercially successful Stirling powered submarines during the 1980s. As of 2005 they have started to carry compressed oxygen with them. (No endurance stated.)


Nuclear power

There is a potential for nuclear-powered Stirling engines in electric power generation plants. Replacing the steam turbines of nuclear power plants with Stirling engines might simplify the plant, yield greater efficiency, and reduce the radioactive by-products. A number of breeder reactor designs use liquid sodium as coolant. If the heat is to be employed in a steam plant, a water/sodium heat exchanger is required, which raises some concern as sodium reacts violently with water. A Stirling engine obviates the need for water anywhere in the cycle.

United States government labs have developed a modern Stirling engine design known as the Stirling Radioisotope Generator for use in space exploration. It is designed to generate electricity for deep space probes on missions lasting decades. The engine uses a single displacer to reduce moving parts and uses high energy acoustics to transfer energy. The heat source is a dry solid nuclear fuel slug and the cold source is space itself.


Aircraft engines

They hold theoretical promise as aircraft engines. They are quieter, less polluting, gain efficiency with altitude (internal combustion piston engines lose efficiency), are more reliable due to fewer parts and the absence of an ignition system, produce much less vibration (airframes last longer) and safer, less explosive fuels may be used. (see below "Argument on why the Stirling engine can be applied in aviation" or "Why Aviation Needs the Stirling Engine" by Darryl Phillips, a 4-part series in the March 1993 to March 1994 issues of Stirling Machine World)


Geothermal energy

Some believe that the ability of the Stirling engine to convert geothermal energy to electricity and then to hydrogen may well hold the key to replacement of fossil fuels in a future hydrogen economy.


Low temperature difference engines

A low temperature difference (Low Delta T) Stirling engine will run on any low temperature differential, for example the difference between the palm of a hand and room-temperature. Usually they are designed in a gamma configuration, for simplicity, and without a regenerator. They are typically unpressurized, running at near-atmospheric pressure. The power produced is less than one watt, and they are intended for demonstration purposes only. As of 2006, this is the only type of Stirling that is widely sold at affordable prices.

Advantages and Disadvantage of Stirling engines

Advantages of Stirling engines

* The heat is external and the burning of a fuel-air mixture can be more accurately controlled.

* They can run directly on any available heat source, not just one produced by combustion, so they can be employed to run on heat from solar, geothermal, biological or nuclear sources.

* A continuous combustion process can be used to supply heat, so emission of unburned fuel can be greatly reduced.

* Most types of Stirling engines have the bearing and seals on the cool side; consequently, they require less lubricant and last significantly longer between overhauls than other reciprocating engine types.

* The engine as a whole is much less complex than other reciprocating engine types. No valves are needed. Fuel and intake systems are very simple.

* They operate at relatively low pressure and thus are much safer than typical steam engines.

* Low operating pressure allows the usage of less robust cylinders and of less weight.

* They can be built to run very quietly and without air, for use in submarines or in space.

* They start easily and run more efficiently in cold weather, features lacking in their internal combustion cousins.

* A Stirling engine which is pumping water can be configured so that the pumped water cools the cool side. This is, of course, most effective when pumping cold water.

* They are extremely flexible. They can be used as CHP (Combined Heat and Power) in winters and as coolers in summers (cryocooling).



Disadvantages of Stirling engines

* Some Stirling engine designs require both input and output heat exchangers, which must contain the pressure of the working fluid, and which must resist any corrosive effects due to the heat source. These increase the cost of the engine, especially when they are designed to the high level of "effectiveness" (heat exchanger efficiency) needed for optimizing fuel economy. Fuel economy may not be an issue with the advantages of using unlimited but unusual fuel sources that a Stirling engine can make use of.

* Stirling engines that run on small temperature differentials are quite large for the amount of power that they produce, due to the heat exchangers. Increasing the temperature differential (and pressure) allows smaller Stirling engines to produce more power.

* Dissipation of waste heat is especially complicated because the coolant temperature is kept as low as possible to maximize thermal efficiency. This drives up the size of the radiators markedly, which can make packaging difficult. This has been one of the factors limiting the adoption of Stirling engines as automotive prime movers. (Conversely, it is convenient for domestic or business heating systems where combined heat and power (CHP) systems show promise. ref)

* A "pure" Stirling engine cannot start instantly; it literally needs to "warm up". This is true of all external combustion engines, but the warm up time may be shorter for Stirlings than for others of this type such as steam engines. Stirling engines are best used as constant run, constant speed engines.

* Power output of a Stirling is constant and hard to change rapidly from one level to another. Typically, changes in output are achieved by varying the displacement of the engine (often through use of a swashplate crankshaft arrangement) or by changing the mass of entrained working fluid (generally helium or hydrogen). This property is less of a drawback in hybrid electric propulsion or base load utility generation where a constant power output is actually desirable.

* Hydrogen's low viscosity, high thermal conductivity and specific heat makes it the most efficient working gas, in terms of thermodynamics and fluid dynamics, to use in a Stirling engine. However, given the high diffusion rate associated with this low molecular weight gas, hydrogen will leak through solid metal, thus it is very difficult to maintain pressure inside the engine for any length of time without replacement. Typically, auxiliary systems need to be added to maintain the proper quantity of working fluid. These systems can be a gas storage bottle or a gas generator. Hydrogen can be generated either by electrolysis of water, or by the reaction of acid on metal. Hydrogen can also cause the embrittlement of metals. Helium must be supplied by bottled gas. Some engines use air as the working fluid which is less thermodynamically efficient but minimizes the problems of gas containment and supply. Most technically advanced Stirling engines like those developed for United States government labs use helium as the working gas, because it functions close to the efficiency and power density of hydrogen with fewer of the material containment issues. Hydrogen is also a very flammable gas, while helium is inert. Compressed air can also be explosive because it contains a high partial pressure of oxygen. Oxygen can be removed from air through an oxidation reaction, or equivalently, bottled nitrogen can be used.

Stirling engine

The Stirling engine is a heat engine of the external combustion piston engine type. It was invented and developed by Reverend Dr Robert Stirling in 1816.

A well-designed Stirling engine can achieve 50% to 80% of the ideal efficiency in the conversion of heat into mechanical work, limited only by friction and material properties. The engines can theoretically run on any heat source of sufficient temperature, including solar energy, chemical and nuclear fuels.

While the Stirling engine is more expensive and larger than an internal combustion engine of the same power rating, its many unique advantages make it preferred for a variety of niche applications. Compared to internal combustion engines, Stirling engines can be made very energy efficient, quiet, reliable, long-lasting and low-maintenance. In recent years, these advantages have become increasingly significant given the general rise in energy costs and the environmental concerns of climate change. This growing interest in Stirling technology has led to the ongoing development of Stirling devices for many applications, including renewable power generation and Astronautics.

Functional Description


The engine cycle

Since the Stirling engine is a closed cycle, it contains a fixed quantity of gas called a "working fluid", most commonly air, hydrogen or helium. In normal operation, the engine is sealed and no gas enters or leaves the engine. No valves are required, unlike other types of piston engines. The Stirling engine, like most heat-engines, cycles through four main processes: cooling, compression, heating and expansion. This is accomplished by moving the gas back and forth between hot and cold heat exchangers. The hot heat exchanger is in thermal contact with an external heat source, e.g. a fuel burner, and the cold heat exchanger being in thermal contact with an external heat sink, e.g. air fins. A change in gas temperature will cause a corresponding change in gas pressure, while the motion of the piston causes the gas to be alternately expanded and compressed.

The gas follows the behavior described by the gas laws which describe how a gas's pressure, temperature and volume are related. When the gas is heated, because it is in a sealed chamber, the pressure rises and this then acts on the power piston to produce a power stroke. When the gas is cooled the pressure drops and this means that less work needs to be done by the piston to compress the gas on the return stroke, thus yielding a net power output.

When one side of the piston is open to the atmosphere, the operation of the cold cycle is slightly different. As the sealed volume of working gas comes in contact with the hot side, it expands, doing work on both the piston and on the atmosphere. When the working gas contacts the cold side, the atmosphere does work on the gas and "compresses" it. Atmospheric pressure, which is greater than the cooled working gas, pushes on the piston.

To summarize, the Stirling engine uses the potential energy difference between its hot end and cold end to establish a cycle of a fixed amount of gas expanding and contracting within the engine, thus converting a temperature difference across the machine into mechanical power.

The greater the temperature difference between the hot and cold sources, the greater the power produced, and thus, the lower the efficiency required for the engine to run.

Small demonstration engines have been built which will run on a temperature difference of around 15 °C, e.g. between the palm of a hand and the surrounding air, or between room temperature and melting water ice.



The Regenerator

In true Stirling engines a regenerator, typically a mass of metal wire, is located in the path of the gas between the hot and cold heat exchangers. As the gas cycles between the hot and cold sides, its heat is temporarily transferred to and from the regenerator. In some designs, there is a displacer piston but no regenerator. The displacer piston does not have a seal, and with loose fit tolerances a small air gap between the piston and the cylinder allows the gas to flow around the displacer as it is displaced to the other end of the cylinder. In some designs, the surfaces of the displacer and cylinder alone can provide some regeneration. The regenerator contributes greatly to the overall efficiency and power produced by the Stirling engine. The regenerator was the key feature invented by Robert Stirling in 1816 which greatly improved his machine and distinguished it from other "hot air engines".

The regenerator is a reverse flow heat exchanger, which tends to improve thermal efficiency wherever it is found in technology or in nature.



Engine configurations

The Beta and Gamma type Stirling engines use a displacer piston to move the working gas back and forth between hot and cold heat exchangers. The alpha type engine relies on interconnecting the power pistons of multiple cylinders to move the working gas, with the cylinders held at different temperatures.

The ideal Stirling engine cycle has the same theoretical efficiency as a Carnot heat engine (for the same input and output temperatures). The thermodynamic efficiency varies, but can be higher than steam engines and many modern internal combustion engines (Diesel or Gasoline ).


Engineers classify Stirling engines into three distinct types:


Alpha Stirling

* An alpha Stirling contains two separate power pistons in separate cylinders, one "hot" piston and one "cold" piston. The hot piston cylinder is situated inside the higher temperature heat exchanger and the cold piston cylinder is situated inside the low temperature heat exchanger. This type of engine has a very high power-to-volume ratio but has technical problems due to the usually high temperature of the "hot" piston and the durability of its seals.


Beta Stirling

* A beta Stirling has a single power piston arranged within the same cylinder on the same shaft as a displacer piston. The displacer piston is a loose fit and does not extract any power from the expanding gas but only serves to shuttle the working gas from the hot heat exchanger to the cold heat exchanger. When the working gas is pushed to the hot end of the cylinder it expands and pushes the power piston. When it is pushed to the cold end of the cylinder it contracts and the momentum of the machine, usually enhanced by a flywheel, pushes the power piston the other way to compress the gas. Unlike the alpha type, the beta type avoids the technical problems of hot moving seals.



Gamma Stirling

* A gamma Stirling is simply a beta Stirling in which the power piston is mounted in a separate cylinder alongside the displacer piston cylinder, but is still connected to the same flywheel. The gas in the two cylinders can flow freely between them but remains a single body. This configuration produces a lower compression ratio but is mechanically simpler and often used in multi-cylinder Stirling engines.



Other types

Changes to the configuration of mechanical Stirling engines continue to interest engineers and inventors. Notably, some are in pursuit of the rotary Stirling engine; the goal here is to convert power from the Stirling cycle directly into torque, a similar goal to that which led to the design of the rotary combustion engine. No practical engine has yet been built but a number of concepts, models and patents have been produced.

There is also a field of "free piston" Stirling cycles engines, including those with liquid pistons and those with diaphragms as pistons.

An alternative to the mechanical Stirling engine is the fluidyne pump, which uses the Stirling cycle via a hydraulic piston. In its most basic form it contains a working gas, a liquid and two non-return valves. The work produced by the fluidyne goes into pumping the liquid.



Heat sources

Any temperature difference will power a Stirling engine and the term "external combustion engine" often applied to it is misleading. A heat source may be the result of combustion but can also be solar, geothermal, or nuclear or even biological. Likewise a "cold source" below the ambient temperature can be used as the temperature difference. A cold source may be the result of a cryogenic fluid or iced water. Since small differential temperatures require large mass flows, parasitic losses in pumping the heating or cooling fluids rise and tend to reduce the efficiency of the cycle.

Because a heat exchanger separates the working gas from the heat source, a wide range of combustion fuels can be used, or the engine can be adapted to run on waste heat from some other process. Since the combustion products do not contact the internal moving parts of the engine, a Stirling engine can run on landfill gas containing siloxanes without the accumulation of silica that damages internal combustion engines running on this fuel. The life of lubricating oil is longer than for internal-combustion engines.

The U.S. Department of Energy in Washington, NASA Glenn Research Center in Cleveland, and Stirling Technology Co. of Kennewick, Wash., are developing a free-piston Stirling converter for a Stirling Radioisotope Generator. This device would use a plutonium source to supply heat.



History and development

Invention of the Stirling engine is credited to the Scottish clergyman Rev. Robert Stirling who, in 1816, made significant improvements to earlier designs and took out the first patent. He was later assisted in its development by his engineer brother James Stirling.

The inventors sought to create a safer alternative to the steam engines of the time, whose boilers often exploded due to the high pressure of the steam and the inadequate materials. Stirling engines will convert any temperature difference directly into movement.

Devices called air engines have been recorded from as early as 1699 around the time when the laws of gases were first set out. The English inventor Sir George Cayley is known to have devised air engines c. 1807. Robert Stirling's innovative contribution of 1816 was what he called the 'Economiser'. Now known as the regenerator, it stored heat from the hot portion of the engine as the air passed to the cold side, and released heat to the cooled air as it returned to the hot side. This innovation improved the efficiency of Stirling's engine enough to make it commercially successful in particular applications, and has since been a component of every air engine that is called a Stirling engine.

During the nineteenth century the Stirling engine found applications anywhere a source of low to medium power was required, a role that was eventually usurped by the electric motor at the century's end.

It was also employed in reverse as a heat pump to produce early refrigeration.

In the late 1940s, the Philips Electronics company in The Netherlands was searching for a versatile electricity generator to enable worldwide expansion of sales of its electronic devices in areas with no reliable electricity infrastructure. The company put a huge R&D research effort into Stirling engines building on research it had started in the 1930s and which lasted until the 1970s. The only lasting commercial product for Philips was its reversed Stirling engine: the Stirling cryocooler.

Los Alamos National Laboratory has developed an "Acoustic Stirling Heat Engine" with no moving parts. It converts heat into intense acoustic power which (quoted from given source) "can be used directly in acoustic refrigerators or pulse-tube refrigerators to provide heat-driven refrigeration with no moving parts, or ... to generate electricity via a linear alternator or other electroacoustic power transducer".



The Stirling Cycle

The ideal stirling cycle consists of four thermodynamic processes acting on the working fluid:

* 1. Isothermal Compression
* 2. Constant-Volume (or isometric) heat-addition
* 3. Isothermal Expansion
* 4. Constant-Volume (or isometric) heat-removal

Overhead valve

In automotive engineering, an overhead valve internal combustion engine is one in which the intake and exhaust valves and ports are contained in the cylinder head.

The original overhead valve or OHV piston engine was developed by the Scottish-American David Dunbar Buick. It employed pushrod-actuated valves parallel to the pistons and this is still in use today. This contrasts with previous designs which made use of side valves and sleeve valves.

Today the technology is widespread, and the term, "OHV", is generally used to differentiate a pushrod engine from one which uses overhead cams, although both types employ overhead valves and so are both OHV engines.

Overhead camshaft

Overhead camshaft (OHC) valvetrain configurations place the camshaft within the cylinder heads, above the combustion chambers, and drive the valves or lifters directly instead of using pushrods. When compared directly with pushrod (or I-Head) systems with the same number of valves, the reciprocating components of the OHC system are fewer and in total will have less mass. Though the system that drives the cams may become more complex, most engine manufacturers easily accept the added complexity in trade for better engine performance and greater design flexibility. The OHC system can be driven using the same methods as an I-Head system, these methods may include using a timing belt, chain, or in less common cases, gears.

Many OHC engines today employ Variable Valve Timing and multiple valves to improve efficiency and power. OHC also inherently allows for greater engine speeds over comparable cam-in-block designs.

There are two overhead camshaft layouts:

* Single overhead camshaft (SOHC)
* Double overhead camshafts (DOHC)



Single overhead camshaft

Single overhead camshaft is a design in which one camshaft is placed within the cylinder head. In an inline engine this means there is one camshaft in the head, while in a V engine there are two camshafts: one per cylinder bank.

The SOHC design is inherently mechanically more efficient than a comparable pushrod design. This allows for higher engine speeds, which in turn will by definition increase power output for a given torque. The cam operates the valves directly or through a rocker arm as opposed to overhead valve pushrod engines, which have tappets, long pushrods and rocker arms to transfer the movement of the lobes on the camshaft in the engine block to the valves in the cylinder head.

SOHC designs offer reduced complexity compared to pushrod designs when used for multivalve heads, in which each cylinder has more than two valves.



Double overhead camshafts

A double overhead camshaft (also called double overhead cam, dual overhead cam or twincam) valvetrain layout is characterized by two camshafts being located within the cylinder head, where there are separate camshafts for inlet and exhaust valves. In engines with more than one cylinder bank (V engines) this designation means two camshafts per bank, for a total of four.

Double overhead camshafts are not required in order to have multiple inlet or exhaust valves, but are necessary for more than 2 valves that are directly actuated (though still usually via tappets). Not all DOHC engines are multivalve engines — DOHC was common in two valve per cylinder heads for decades before multivalve heads appeared, however today DOHC is synonymous with multivalve heads, since almost all DOHC engines have between three and five valves per cylinder.



History

The first DOHC engines were two valve per cylinder designs from companies like Fiat (1912), Peugeot (1913), Alfa Romeo (6C- 1925, 512 - 1940), Maserati (Tipo 26, 1926), and Bugatti (Type 51, 1931). Most Ferraris used two valve per cylinder DOHC engines as well.

When DOHC technology was introduced in mainstream vehicles, it was common for the technology to be heavily advertised. While the technology was used at first in limited production and sports cars, the Fiat group is historically credited as the first car company to use a belt driven DOHC engine across their complete product line, comprised of coupes, sedans, convertibles and station wagons, in the mid-1960s.

Honda D engine

The Honda D engine is a family of inline 4-cylinder engines used in a variety of compact Honda models, most commonly the Honda Civic, but also used in the Integra, Logo, CRX, Stream and others. Displacement ranges between 1.2 L and 1.7 L, and the engine is available in SOHC and DOHC versions. Some SOHC models are equipped with VTEC. Power range started from 62 hp (currently the smallest engine uses a 1.4 L 90 hp engine, code D14A4) to 135 hp. The D-series was introduced in 1984 and ended production in 2005 with the introduction of the 8th generation Honda Civic.



Hot-rodding the D series

Although the availability of used D-series engines at low prices makes it somewhat popular among those who modify it for high performance (as well as a popular item for swapping into earlier or less powerful Civics for an instant and trouble free power upgrade), the unmodified engine won't survive quite as much power enhancement by use of such external modifications as turbochargers, superchargers, or nitrous oxide as the more powerful, somewhat more robust, and much more expensive B-series;

The Achilles heel of the D-series seems to be the connecting rods, which will withstand a substantial and noticeable increase in power up to a certain point, but will break if that limit is exceeded. Generally, a D-series motor can handle up to about 220 bhp, as long as care is taken to avoid detonation through careful spark and fuel management. Of course, the connecting rods, pistons, and other internal parts can be replaced with more durable aftermarket parts which will survive almost any amount of power desired, but some people choose to swap to a B-series motor instead in order to avoid the potential risks of engine building. In all practicality though, the B series is much more expensive to swap in than most D-series engine builds with forced induction or nitrous combined. The D-series also has the ability to swap some parts between different motors and among some B-series parts as well.

When employing forced induction on a D16, at a minimum the stock hypereutectic pistons should be replaced as well as the connecting rods if the commonly used "stock parts" limit of 220 HP is to be exceeded, although it should be noted that the D series crankshaft in particular has been found to reliably handle up to 600HP.

High compression OEM pistons are a quick way to gain horsepower in a naturally aspirated motor. All D-series motors run the same bore (75 mm) however, most factory motor variations (i.e. d16a1, d15b7, d16y7) have used a different piston compression height as well as a different dome or dish. In general, the older D motors have a higher compression height and a larger combustion chamber which create around a 9.1:1 - 9.4:1 compression ratio from the factory. The newer variants have slightly lower compression height combined with a much smaller combustion chamber to create a compression ratio of 9.4:1 - 9.9:1. Now if you combine an older d16 motor's piston with that of a newer d16 head you can end up with a compression ratio of about 10.7:1 with no other work (i.e. D16A1 piston, D16A6 head). There are a few websites that have compression ratio calculators for Honda motors.

·D15 has smaller main bearing diameters. D16 and D17 cranks share the same size main bearing diameters.

·D16 and D17 rods all have the same major dimensions. The D15 rod is shorter (in general) and has a smaller bearing size, although the wrist pin bore is the same.

·D15Z1 and D15B motors have a rod that is the same length as a D16. Other than the rod length, the rest of the bottom end is D15 spec (i.e. rod and crank bearings). D15B has D16 sized rod journals. D15B uses the same p28 rods that the D16z6 does. All other D15s have smaller rod journals.

·The B18A/B Rod has the same bearing bore as a D16. It is 0.044" wider, so the sides of the "big end" of the rod have to be shaved down for use in a D16/17. The wrist pin bore is larger so a conventional D15/16/17 piston can only be used if the stock "small end" bushing in the rod is replaced with one of the proper size. These affordable rods are generally considered to be able to handle up to 300 HP.

·There is a D16 motor that runs on compressed natural gas (96-98 Civic GX). The pistons from that motor have a 12.5:1 CR. The wrist pin bore in the 98-00 D16B5 is 21 mm, like the B18B rod. D17A7 01-05 Civic GX uses 19 mm wrist pins.

·Interestingly enough, the Suzuki Vitara has a 75mm bore as well, so engine builders have occasionally used these pistons in the D16 motor. These pistons are commonly referred to as Vitaras, and they provide an 8.5:1 compression ratio, and thicker ring lands. Lowering the stock compression ratio lowers compression heat, which raises the detonation thresh-hold and is useful when employing forced induction.



Mini-Me

One of the most popular and effective methods of achieving greater power from a D-series motor is replacing the cylinder head with one from a more powerful D-series motor. This is usually done between D16A6 and D16Z6 or D16Y7 and D16Y8 engines. The Z6 and Y8 heads are VTEC (Variable Valve Timing and Lift Electronic Control) equipped, and increase horsepower significantly over stock levels. This operation is known as a "Mini Me" or partial swap. Mini Me's are popular because they offer a substantial performance upgrade by adding VTEC to the motor at a relatively low cost.


Engine Specs


D13 Series Engines (1.3 Litre)

D13B1

* Found in:
o 1987-1991 Honda Civic DX (European Market)
+ Displacement : 1343 cm3
+ Bore and Stroke : 75 mm X 76 mm
+ Compression : 9.5:1
+ Power, Torque : n/s (Not stated in Owners Manual)
+ Valvetrain : SOHC, 4 valves per cylinder
+ Fuel Control : Single Carburettor


D13B2

* Found in:
o 1992-1995 Honda Civic DX (European Market)
+ Displacement : 1343 cm3
+ Bore and Stroke : 75 mm X 76 mm
+ Compression : 9:1
+ Power, Torque : 75 hp @ 5300 rpm
+ Valvetrain : SOHC, 4 valves per cylinder
+ Fuel Control : Carburettor


D14 Series Engines (1.4 Litre)

D14A1

* Found in:
o 1987-1991 Honda Civic GL and 1990 CRX (European Market)
+ Displacement : 1396 cm3
+ Bore and Stroke : 75 mm X 79 mm
+ Compression : 9.3:1
+ Power, Torque : 90 ps (90 bhp) @ 6300 rpm, 112Nm @ 4500 rpm
+ Valvetrain : SOHC, 4 valves per cylinder
+ Fuel Control : Dual Carburettor


D14A2

* Found in:
o 1995-1996 Honda Civic MA8 (European Market)
+ Displacement : 1396 cm3
+ Bore and Stroke : 75.0 mm X 79.0 mm
+ Compression : 9.2:1
+ Power, Torque : 66kW @ 6100 rpm, 117Nm @ 5000 rpm
+ Valvetrain : SOHC, 4 valves per cylinder
+ Fuel Control : PGM-FI


D15 Series Engines (1.5 Liters)

D15A2

* Found in:
o 1984-1987 Honda CRX HF
+ Displacement : 1488 cm3
+ Bore and Stroke : 74 mm X 86.5 mm
+ Compression : 9.6:1
+ Power : 58 hp @ 4500 rpm & 80 ft·lbf @ 2500 rpm
+ Valvetrain : SOHC
+ Fuel Control : carburete


D15A3

* Found in:
o 1985-1987 Honda CRX Si and 1987 Civic Si (AU/NZ)
+ Displacement : 1488 cm3
+ Bore and Stroke : 74 mm X 86.5 mm
+ Compression : 8.7:1
+ Power : 91 hp @ 5500 rpm & 93 ft·lbf @ 4500 rpm
+ Valvetrain : SOHC, 3 valves/cylinder
+ Fuel Control : Fuel Injected, Multi-point PGM-FI


D15B

* VTEC
* Found in:
o 1991-1999 Honda Civic VTi EG4 (Japanese Market)
+ Displacement : 1493 cm3
+ Bore and Stroke : 75 mm X 84.5 mm
+ Rod Length : 137 mm
+ Compression : 9.6:1
+ Power : 130 hp @ 6800 rpm & 102 ft·lbf @ 5200 rpm
+ Valvetrain : SOHC VTEC
+ Fuel Control : OBD-1 MPFI

* 3-stage VTEC
* Found in:
o 1996-1999 Honda Civic VTi EK3 and Ferio Vi
+ Displacement : 1493 cm3
+ Bore and Stroke : 75 mm X 84.5 mm
+ Rod Length : 137 mm
+ Compression : 9.6:1
+ Power : 130 hp @ 6800 rpm & 102 ft·lbf @ 5200 rpm
+ Valvetrain : SOHC VTEC
+ Fuel Control : OBD-2 MPFI


D15B1

(Essentially a D15B2 engine with a mild camshaft, a restrictor plate under the DPFI, and an air flow restricton in the DPFI unit)

* Found in:
o 1988-1991 Honda Civic STD Hatchback
+ Displacement : 1493 cm3
+ Bore and stroke : 75 mm X 84.5 mm
+ Compression : 9.2:1
+ Power : 70 hp @ 5500 rpm & 83 ft·lbf @ 3000 rpm
+ Valvetrain : SOHC (4 valves per cylinder)
+ Fuel Control : OBD-O DPFI


D15B2

* Found in:
o 1988-1991 Honda Civic DX/LX, CRX DX, Civic Wagon DX/Wagovan,
o 1992-1995 Honda Civic Hatchback LSi (European Market)
+ Displacement : 1493 cm3
+ Bore and Stroke : 75 mm X 84.5 mm
+ Compression : 9.2:1
+ Power : 92 hp @ 6000 rpm & 89 ft·lbf @ 4500 rpm
+ Valvetrain : SOHC (4 valves per cylinder)
+ Fuel Control : OBD-0 DPFI


D15B6

* Found in:
o 1988-1991 Honda CRX HF
+ Displacement : 1493 cm3
+ Bore and Stroke : 75 mm X 84.5 mm
+ Compression : 9.1:1
+ Power : 62 hp(88-89) 70 hp(90-91)@ 4500 & 83 ft·lbf @ 3000 rpm
+ Valvetrain : SOHC (2 valves per cylinder)
+ Fuel Control : OBD-0 MPFI


D15B7

* Found in:
o 1992-1995 Honda Civic DX/LX
o 1992-1995 Honda Civic LSi Coupe (European Market)
+ Displacement : 1493 cm3
+ Bore and Stroke : 75 mm X 84.5 mm
+ Compression : 9.2:1
+ Power : 102 hp @ 5900 rpm & 98 ft·lbf @ 5000 rpm
+ Valvetrain : SOHC (4 valves per cylinder)
+ Fuel Control : OBD-1 MPFI


D15B8

* Found in:
o 1992-1995 Honda Civic CX
+ Displacement : 1493 cm3
+ Bore and Stroke : 75 mm X 84.5 mm
+ Compression : 9.1:1
+ Power : 100 hp @ 4500 rpm & 83 ft·lbf @ 3000 rpm
+ Valvetrain : SOHC (2 valves per cylinder)
+ Fuel Control : OBD-1 MPFI

ITS 70 HP!!


D15Z1

* VTEC-E
* Found in:
o 1992-1995 Honda Civic VX
o 1992-1995 Honda Civic VEi (European Market)
+ Displacement : 1493 cm3
+ Bore and Stroke : 75 mm X 84.5 mm
+ Rod Length : 137 mm
+ Compression : 9.3:1
+ Power : 92 hp @ 5500 rpm & 97 ft·lbf @ 4500 rpm
+ VTEC Switchover : 2500 rpm
+ Valvetrain : SOHC VTEC-E (4 valves per cylinder)
+ Fuel Control : OBD-1 MPFI


D16 Series Engines (1.6 Liters)

D16A1

* Found in:
o 1986-89 Acura Integra (North America)
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.3:1
+ Power : 113 hp @ 6250 rpm & 99 ft·lbf @ 5500 rpm
+ Valvetrain : DOHC
+ Fuel Control : OBD-0 MPFI


D16A3

* Found in:
o 1986-89 Acura Integra (Australia)
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.5:1
+ Power : 118 hp @ 6500 rpm & 103 ft·lbf @ 5500 rpm
+ Valvetrain : DOHC
+ Fuel Control : OBD-0 MPFI


D16A6

* Found in:
o 1988-1991 Honda Civic Si, CRX Si, Civic Wagon RT4WD
o 1988-1995 Honda Civic Shuttle RT4WD (UK/Europe/Asia/AU/NZ)
o 1989-1996 Rover 216/416 GTI (UK/Europe)
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.6:1
+ Power : 110 hp @ 6000 rpm & 100 ft·lbf @ 5000 rpm
+ Valvetrain : SOHC
+ Fuel Control : OBD-0 Multi-point PGM-FI
+ Head Code : PM3


D16A8

* Found in:
o 1988-1991 Civic/CRX/Concerto (UK/Europe/Australia)
o 1990-1995 Rover 216/416 (UK/Europe)
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.5:1
+ Power : 122 hp @ 6800 rpm & 108 ft·lbf @ 5700 rpm
+ Valvetrain : DOHC
+ Fuel Control : OBD-0 MPFI


D16A9

* Found in:
o 1988-1991 Civic/CRX/Concerto (UK/Europe)
o 1989-1996 Rover 216/416 GTI (UK/Europe)
o 1992-1995 Civic Si (Peruvian version)
o 1992-1995 Civic GTi
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.5:1
+ Power : 130 hp @ 6800 rpm & 108 ft·lbf @ 5700 rpm
+ Valvetrain : DOHC
+ Fuel Control : OBD-0 MPFI


D16Y5

* VTEC-E
* Found in:
o 1996-2000 Honda Civic HX
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.4:1
+ Power : 115 hp@ 6200 rpm & 104 ft·lbf @ 5400 rpm
+ Valvetrain : SOHC VTEC-E
+ Fuel Control : OBD-2 MPFI
+ Head Code : PJ2


D16Y7

* Found in:
o 1996-2000 Honda Civic DX/LX/CX, 1996-97 Del Sol S
+ Displacement : 1593 cm3
+ Bore and Stroke : 75.5 mm X 90 mm
+ Compression : 9.4:1
+ Power : 106 hp @ 6200 rpm
+ Torque (ft·lb@rpm): 103 (141 N·m) @ 4,600 rpm
+ Valvetrain : SOHC
+ Fuel Control : OBD-2 MPFI
+ Head Code : P2F


D16Y8

* VTEC
* Found in:
o 1996-2000 Honda Civic EX
o 1996-1998 Honda Civic Coupe SiR (UK model
o 1997-2000 Acura 1.6EL
o 1996-1998 Honda Civic Si
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.6:1
+ Power : 127 hp @ 6600 rpm & 107 ft·lbf @ 5500 rpm
+ VTEC Switchover: 5200 rpm
+ Valvetrain : SOHC VTEC
+ Fuel Control : OBD-2 MPFI
+ Head Code : P2J


D16Z6

* VTEC
* Found in:
o 1992-1995 Honda Civic EX/Si, Del Sol Si,
o 1992-1995 Honda Civic ESi (European Market)
+ Displacement : 1590 cm3
+ Bore and Stroke : 75 mm X 90 mm
+ Compression : 9.4:1
+ Power : 125 hp @ 6500 rpm & 106 ft·lbf @ 5200 rpm
+ VTEC Switchover 4800 rpm
+ Valvetrain : SOHC VTEC
+ Fuel Control : OBD-1 MPFI
+ Head Code : P08


D17 Series Engines (1.7 Liters)

D17A1

* Found in:
o 2001-2005 Honda Civic DX/LX/VP
+ Displacement : 1668 cm3
+ Bore and Stroke : 75 mm X 94.4 mm
+ Compression : 9.5:1
+ Power : 5646 hp @ 6100 rpm & 110 ft·lbf @ 4500 rpm
+ Valvetrain : SOHC
+ Fuel Control : OBD-2 MPFI


D17A2

* VTEC
* Found in:
o 2001-2005 Honda Civic EX
+ Displacement : 1668 cm3
+ Bore and Stroke : 74.98 mm X 94.4 mm
+ Compression : 9.9:1
+ Power : 127 hp @ 6300 rpm & 114 ft·lbf @ 4400 rpm
+ Valvetrain : SOHC VTEC-E
+ Fuel Control : OBD-2 MPFI


D17A6

* VTEC-E
* Found in:
o 2001-2005 Honda Civic HX
+ Displacement : 1668 cm3
+ Bore and Stroke : 75 mm X 94.4 mm
+ Compression : 9.5:1
+ Power : 170 hp @ 6100 rpm & 111 ft·lbf @ 4500 rpm
+ Valvetrain : SOHC VTEC-E
+ Fuel Control : OBD-2 MPFI


D17A7

* Found in:
o 2004-2005 Honda Civic DX
o Uses CNG (Compressed Natural Gas)
+ Displacement : 1668 cm3
+ Bore and Stroke : 75 mm X 94.4 mm
+ Compression : 12.5:1
+ Power : 100 @ 6100 rpm & 98 ft·lbf @ 4000 rpm
+ Valvetrain : SOHC
+ Fuel Control : OBD-2 MPFI

Initial List created from Honda Engine List (6-19-2006). on HondaSwap.com



ZC (similar to D16A1, D16A3, D16A6, D16A8 and D16A9 engines)

A few D-series variants are labelled "ZC" (usually JDM), but they are not truly a different series. There are both SOHC and DOHC ZC engines. The SOHC ZC is similar to the D16A6 engine, and the DOHC ZC is similar to the D16A1, D16A3, D16A8 and D16A9 engines.

Euro Mk1 (85-87) 1.6 CRX's are fitted with an engine designated "ZC1" which is a higher spec 125bhp version of the D16a1.

Types of bearings

There are many types of rolling-element bearings, each tuned for a specific kind of load and with specific advantages and disadvantages. For example:


Ball bearings

Ball bearings use spheres instead of cylinders. Clever use of surface tension allows balls of high accuracy to be made much more cheaply than comparable cylinders. Ball bearings can support both radial (perpendicular to the shaft) and axial loads (parallel to the shaft). For lightly-loaded bearings, balls offer lower friction than rollers. Ball bearings can operate when the bearing races are misaligned.



Roller bearings

Common roller bearings use cylinders of slightly greater length than diameter. Roller bearings typically have higher radial load capacity than ball bearings, but a low axial capacity and higher friction under axial loads. If the inner and outer races are misaligned, the bearing capacity often drops quickly compared to either a ball bearing or a spherical roller bearing.

Roller bearings are the earliest known type of rolling-element-bearing, dating back to at least 40 BC.



Needle bearing

Needle roller bearings use very long and thin cylinders. Since the rollers are thin, the outside diameter of the bearing is only slightly larger than the hole in the middle. However, the small-diameter rollers must bend sharply where they contact the races, and thus the bearing fatigues relatively quickly.



Tapered roller bearing

Tapered roller bearings use conical rollers that run on conical races. Most roller bearings only take radial loads, but taper roller bearings support both radial and axial loads, and generally can carry higher loads than ball bearings due to greater contact area. Taper roller bearings are used, for example, as the wheel bearings of most cars, trucks, buses, and so on. The downsides to this bearing is that due to manufacturing complexities, tapered roller bearings are usually more expensive than ball bearings; and additionally under heavy loads the tapered roller is like a wedge and bearing loads tend to try to eject the roller; the force from the collar which keeps the roller in the bearing adds to bearing friction compared to ball bearings.




Spherical roller bearings

* Spherical roller bearings use rollers that are thicker in the middle and thinner at the ends; the race is shaped to match. Spherical roller bearings can thus adjust to support misaligned loads. However, spherical rollers are difficult to produce and thus expensive. And, the bearings have higher friction than a comparable ball bearing since different parts of the spherical rollers run at different speeds on the rounded race and thus there are opposing forces along the bearing/race contact.




Thrust bearing

An axial load is supported by this type, typically to support a vertical shaft against gravitational loads. (Contrary to the illustration, either spherical or conical rollers are typically used.)



Other types

Most rolling-element bearing designs are for rotating or oscillating loads, but there are also linear bearing designs. A common example is drawer-support hardware. Another example is a bearing for a shaft which moves axially in a hole. Axial-motion bearings often work like the stone-and-log example, with a pathway so rolling elements that fall off the end are pushed around to the other end, and the load rolls on to it. These are called recirculating bearings and were used in automotive steering units before the extensive introduction of the rack and pinion unit.



Bearing failure

Rolling-element bearings often work well in non-ideal conditions. But sometimes minor problems cause bearings to fail quickly and mysteriously. For example, with a stationary (non-rotating) load, small vibrations can gradually press out the lubricant between the races and rollers or balls (False brinelling). Without lubricant the bearing fails, even though it is not rotating and thus is apparently not being used. For these sorts of reasons, much of bearing design is about failure analysis.

There are three usual limits to the lifetime or load capacity of a bearing: abrasion, fatigue and pressure-induced welding. Abrasion is when the surface is eroded by hard contaminants scraping at the bearing materials. Fatigue is when a material breaks after it is repeatedly bent and released. Where the ball or roller touches the race there is always some bending, and hence a risk of fatigue. Smaller balls or rollers bend more sharply, and so tend to fatigue faster. Pressure-induced welding is when two metal pieces are pressed together at very high pressure and they become one. Although balls, rollers and races may look smooth, they are microscopically rough. Thus, there are high-pressure spots which push away the bearing lubricant. Sometimes, the resulting metal-to-metal contact welds a tiny part of the ball or roller to the race. As the bearing continues to rotate, the weld is then torn apart, but it may leave race welded to bearing or bearing welded to race.

Although there are many other apparent causes of bearing failure, most can be reduced to these three. For example, a bearing which is run dry of lubricant fails not because it is "without lubricant", but because lack of lubrication leads to fatigue and welding, and the resulting wear debris can cause abrasion. Similar events occur in false brinelling damage.



Constraints and trade-offs

All parts of a bearing are subject to many design constraints. For example, the inner and outer races are often complex shapes, making them difficult to manufacture. Balls and rollers, though simpler in shape, are small; since they bend sharply where they run on the races, the bearings are prone to fatigue. The loads within a bearing assembly are also affected by the speed of operation: rolling-element bearings may spin over 100,000 rpm, and the principal load in such a bearing may be centrifugal force rather than the applied load. Smaller rolling elements are lighter and thus have less centrifugal force, but smaller elements also bend more sharply where they contact the race, causing them to fail more rapidly from fatigue.

There are also many material issues: a harder material may be more durable against abrasion but more likely to suffer fatigue fracture, so the material varies with the application, and while steel is most common for rolling-element bearings, plastics, glass, and ceramics are all in common use. A small defect (irregularity) in the material is often responsible for bearing failure; one of the biggest improvements in the life of common bearings during the second half of the 1900s was the use of more homogeneous materials, rather than better materials or lubricants (though both were also significant). Lubricant properties vary with temperature and load, so the best lubricant varies with application.

Although bearings tend to wear out with use, designers can make tradeoffs of bearing size and cost versus lifetime. A bearing can last indefinitely -- longer than the rest of the machine -- if it is kept cool, clean, lubricated, is run within the rated load, and if the bearing materials are sufficiently free of microscopic defects. Note that cooling, lubrication, and sealing are thus important parts of the bearing design.

The needed bearing lifetime also varies with the application. For example, Harris reports on an oxygen pump bearing in the U.S. Space Shuttle which could not be adequately isolated from the liquid oxygen being pumped, but all lubricants reacted with the oxygen leading to fires and other failures. The solution was to lubricate the bearing with the oxygen. Although liquid oxygen is a poor lubricant, it was adequate, since the service life of the pump was just a few hours.

The operating environment and service needs are also important design considerations. Some bearing assemblies require routine addition of lubricants, while others are factory sealed, requiring no further maintenance for the life of the mechanical assembly. Although seals are appealing, they increase friction, and a permanently-sealed bearing may have the lubricant contaminated by hard particles, such as steel chips from the race or bearing, sand, or grit that got past the seal. Contamination in the lubricant is abrasive and greatly reduces the operating life of the bearing assembly.

Rolling-element bearing

A rolling-element bearing is a bearing which carries a load by placing round elements between the two pieces. The relative motion of the pieces causes the round elements to roll (tumble) with little sliding.

One of the earliest and best-known rolling-element bearings are sets of logs laid on the ground with a large stone block on top. As the stone is pulled, the logs roll along the ground with little sliding friction. As each log comes out the back, it is moved to the front where the block then rolls on to it. You can imitate such a bearing by placing several pens or pencils on a table and placing your hand on top of them. See "bearings" for more on the historical development of bearings.

A rolling-element rotary bearing uses a shaft in a much larger hole, and cylinders called "rollers" tightly fill the space between the shaft and hole. As the shaft turns, each roller acts as the logs in the above example. However, since the bearing is round, the rollers never fall out from under the load.

Rolling-element bearings have the advantage of a good tradeoff between cost, size, weight, carrying capacity, durability, accuracy, friction, and so on. Other bearing designs are often better on one specific attribute, but worse in most other attributes, although fluid bearings can sometimes simultaneously outperform on carrying capacity, durability, accuracy, friction, rotation rate and sometimes cost. Only plain bearings have as wide use as rolling-element bearings.



Design

Typical rolling-element bearings range in size from 10 mm diameter to a few metres diameter, and have load-carrying capacity from a few tens of grams to many thousands of tonnes.

A particularly common kind of rolling-element bearing is the ball bearing. The bearing has inner and outer races and a set of balls. Each race is a ring with a groove where the balls rest. The groove is usually shaped so the ball is a slightly loose fit in the groove. Thus, in principle, the ball contacts each race at a single point. However, a load on an infinitely small point would cause infinitely high contact pressure. In practice, the ball deforms (flattens) slightly where it contacts each race, much as a tire flattens where it touches the road. The race also dents slightly where each ball presses on it. Thus, the contact between ball and race is of finite size and has finite pressure. Note also that the deformed ball and race do not roll entirely smoothly because different parts of the ball are moving at different speeds as it rolls. Thus, there are opposing forces and sliding motions at each ball/race contact. Overall, these cause bearing drag.

Most rolling element bearings use cages to keep the balls separate. This reduces wear and friction, since it avoids the balls rubbing against each other as they roll, and precludes them from jamming. Caged roller bearings were invented by John Harrison in the mid 1700s as part of his work on chronographs.

Crank pin

In a reciprocating engine, the crank pins are the bearing journals of the big end bearings, at the opposite ends of the connecting rods to the pistons. If the engine has a crankshaft, then the crank pins are the journals of the off-centre bearings of the crankshaft. In a beam engine the single crank pin is mounted on the flywheel; In a steam locomotive the crank pins are often mounted directly on the driving wheels.

Big end bearings are commonly plain bearings, but less commonly may be roller bearings, see crankshaft.

In a multi-cylinder engine, a crank pin can serve one or many cylinders, for example:

* In a straight engine each crank pin normally serves only one cylinder.

* In a V engine each crank pin usually serves two cylinders, one in each cylinder bank.

* In a radial engine each crank pin serves an entire row of cylinders.



Big end design

There are three common configurations of big end bearing:

* If a crank pin serves only one cylinder, then the big end is a relatively simple design, accommodating only one connecting rod. This design is the cheapest to produce, and is used in:
o All single cylinder engines.
o Most straight engines.
o All boxer engines.
o Some V-twin engines.

* If a crank pin serves more than one cylinder, then the corresponding cylinders may have an offset, to simplify the design of the big end bearing. This design is used in:
o Most V engines.
o Multiple row radial engines.

* If more than one cylinder is served by a single crank pin but there is no offset, then some or all of the connecting rods must be forked at the big end. This design in theory provides better engine balance than designs with an offset, but at the cost of considerable extra complexity and cost in both design and manufacture, and either more weight or closer manufacturing tolerances or both to achieve the same strength and reliability. Any extra weight added to the big end itself also carries a penalty of adding vibration and reducing balance. As the number of cylinders grows, the effect of the offset on balance becomes less important, and forked connecting rods become less common. They are mainly used in:
o Single-row radial engines.
o Some V-twin engines, notably including motorcycle engines.

Connecting rod

In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft.


Internal combustion engines

In modern automotive internal combustion engines, the connecting rods are most usually made of steel for production engines, but can be made of aluminium (for lightness and the ability to absorb high impact at the expense of durability) or titanium (for a combination of strength and lightness at the expense of affordability) for high performance engines, or of cast iron for applications such as motor scooters. They are not rigidly fixed at either end, so that the angle between the con rod and the piston can change as the rod moves up and down and rotates around the crankshaft.

The small end attaches to the piston pin, gudgeon pin (the usual British term) or wrist pin, which is currently most often press fit into the con rod but can swivel in the piston, a "floating wrist pin" design. The big end connects to the bearing journal on the crank throw, running on replaceable bearing shells accessible via the con rod bolts which hold the bearing "cap" onto the big end; typically there is a pinhole bored through the bearing and the big end of the con rod so that pressurized lubricating motor oil squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings.

The con rod is under tremendous stress from the reciprocating load represented by the piston, actually stretching and relaxing with every rotation, and the load increases rapidly with increasing engine speed. Failure of a connecting rod is one of the most common causes of catastrophic engine failure in cars, frequently putting the broken rod through the side of the crankcase and thereby rendering the engine irreparable; it can result from overheating, fatigue near a physical defect in the rod, lubrication failure in a bearing due to faulty maintenance, or from failure of the rod bolts from a defect, improper tightening, or re-use of already used (stressed) bolts where not recommended. Despite their frequent occurrence on televised competitive automobile events, such failures are quite rare on production cars during normal daily driving. This is because production auto parts have a much larger factor of safety, and often more systematic quality control.

When building a high performance engine, great attention is paid to the con rods, eliminating stress risers by such techniques as grinding the edges of the rod to a smooth radius, shot peening to relieve internal stress, balancing all con rod/piston assemblies to the same weight and Magnafluxing to reveal otherwise invisible small cracks which would cause the rod to fail under stress. In addition, great care is taken to torque the con rod bolts to the exact value specified; often these bolts must be replaced rather than reused. The big end of the rod is fabricated as a unit and cut or cracked in two to establish precision fit around the big end bearing shell. Therefore, the big end "caps" are not interchangeable between con rods, and when rebuilding an engine, care must be taken to ensure that the caps of the different con rods are not mixed up. Both the con rod and its bearing cap are usually embossed with the corresponding position number in the engine block.

Recent engines such as the Ford 4.6 liter engine and the Chrysler 2.0 liter engine, have connecting rods made using powder metallurgy, which allows more precise control of size and weight with less machining and less excess mass to be machined off for balancing. The cap is then separated from the rod by a fracturing process, which results in an uneven mating surface due to the grain of the powdered metal. This ensures that upon reassembly, the cap will be perfectly positioned with respect to the rod, compared to the minor misalignments which can occur if the mating surfaces are both flat.

A major source of engine wear is the sideways force exerted on the piston through the con rod by the crankshaft, which typically wears the cylinder into an oval cross-section rather than circular, making it impossible for piston rings to correctly seal against the cylinder walls. Geometrically, it can be seen that longer con rods will reduce the amount of this sideways force, and therefore lead to longer engine life. However, for a given engine block, the sum of the length of the con rod plus the piston stroke is a fixed number, determined by the fixed distance between the crankshaft axis and the top of the cylinder block where the cylinder head fastens; thus, for a given cylinder block longer stroke, giving greater engine displacement and power, requires a shorter connecting rod (or a piston with smaller compression height), resulting in accelerated cylinder wear.

In certain types of engine, master/slave rods are used rather than the simple type shown in the picture above. The master rod carries one or more ring pins to which are bolted the much smaller big ends of slave rods on other cylinders. Radial engines typically have a master rod for one cylinder and slave rods for all the other cylinders in the same bank. Certain designs of V engines use a master/slave rod for each pair of opposite cylinders. On the other hand, some V engines use simple rods side by side on a single crankpin, or separate crankpins for each cylinder.


Steam engines

In a steam locomotive, the crank pins are often mounted directly on one or more pairs of driving wheels, and the axle of these wheels serves as the crankshaft. The connecting rods, also called the main rods, run between the crank pins and crosshead bearings, where they connect to the piston rods. Crosshead rod systems are also used on large diesel engines manufactured for marine service.

See also steam locomotive nomenclature.

Cam

A cam is a projecting part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other shape that produces a smooth oscillating motion in the follower which is a lever making contact with the cam.


The cam can be seen as a device that translates movement from circular to linear. Another common example is the camshaft of a car or automobile, which takes the rotary motion of the engine and translates it into the linear motion necessary to operate the intake and exhaust valves of the cylinders.

The opposite operation, translation of linear motion to circular motion, is done by a crank. An example is the crankshaft of a car, which takes the linear motion of the pistons and translates it into the rotary motion necessary to operate the wheels.

Certain cams can be characterized by their displacement diagrams which reflect the changing position a roller follower would make as the cam rotates about an axis. These diagrams relate angular position to the radial displacement experienced at that position. Several key terms are relevant in such a construction of plate cams: base circle, prime circle (with radius equal to the sum of the follower radius and the base circle radius), and the pitch curve which is the radial curve traced out by appling the radial displacements away from the prime circle across all angles. Displacement diagrams are traditionally presented as graphs with non-negative values.

Ignition coil

An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system which transforms a storage battery's 12 volts to the thousands of volts needed to spark the spark plugs.

This specific form of the autotransformer, together with the contact breaker, converts low voltage from a battery into the high voltage required by spark plugs in an internal combustion engine.

In older vehicles a single (large) coil would serve all the spark plugs via the ignition distributor.

In modern systems, the distributor is omitted and ignition is instead electronically controlled. Much smaller coils are used with one coil for each spark plug or one coil serving two spark plugs (so two coils in a four-cylinder car). These coils may be remote-mounted or they may be placed on top of the spark plug (coil-on-plug or Direct Ignition). Where one coil serves two spark plugs (in two cylinders), it is through the "wasted spark" system. In this arrangement the coil generates two sparks per cycle to both the cylinders. The fuel in the cylinder that is nearing the end of its compression stroke is ignited, whereas the spark in its companion that is nearing the end of its exhaust stroke has no effect. The wasted spark system is more reliable than a single coil system with a distributor and cheaper than coil-on-plug.

Where the coils are remote mounted they may all be contained in a single moulded block with multiple high-tension terminals. This is commonly called a coil-pack.

Modern ignition systems

Mechanically timed ignition

Most four-stroke engines have used a mechanically timed electrical ignition system. The heart of the system is the distributor which contains a rotating cam running off the engine's drive, a set of breaker points, a condenser, a rotor and a distributor cap. External to the distributor is the ignition coil, the spark plugs, and wires linking the spark plugs and ignition coil to the distributor.

The power source is a lead-acid battery, kept charged by the car's electrical system, which generates electricity using a dynamo or alternator. The engine operates contact breaker points, which interrupt the current flow to an induction coil (known as the ignition coil).

The ignition coil consists of two transformer windings sharing a common magnetic core -- the primary and secondary windings. An alternating current in the primary induces alternating magnetic field in the coil's core. Because the ignition coil's secondary has far more windings than the primary, the coil is a step-up transformer which induces a much higher voltage across the secondary windings. For an ignition coil, one end of windings of both the primary and secondary are connected together. This common point is connected to the battery (usually through a current-limiting resistor). The other end of the primary is connected to the points within the distributor. The other end of the secondary is connected, via the distributor cap and rotor, to the spark plugs.

The ignition firing sequence begins with the points (or contact breaker) closed. A steady current flows from the battery, through the current-limiting resistor, through the coil primary, across the closed breaker points and finally back to the battery. This steady current produces a magnetic field within the coil's core. This magnetic field forms the energy reservoir that will be used to drive the ignition spark.

As the engine turns, so does the cam inside the distributor. The points ride on the cam so that as the engine turns and reaches the top of the engine's compression cycle, a high point in the cam causes the breaker points to open. This breaks the primary winding's circuit and abruptly stops the current flow through the breaker points.

Without the steady current flow through the points, the magnetic field generated in the coil immediately begins to quickly collapse. This rapid decay of the magnetic field induces a high voltage in the coil's secondary windings.

At the same time, current exits the coil's primary winding and begin to charge up the capacitor ("condenser") that lies across the now-open breaker points. This capacitor and the coil’s primary windings form an oscillating LC circuit. This LC circuit produces a damped, oscillating current which bounces energy between the capacitor’s electric field and the ignition coil’s magnetic field. The oscillating current in the coil’s primary, which produces an oscillating magnetic field in the coil, extends the high voltage pulse at the output of the secondary windings. This high voltage thus continues beyond the time of the initial field collapse pulse. The oscillation continues until the circuit’s energy is consumed.

The ignition coil's secondary windings are connected to the distributor cap. A turning rotor, located on top of the breaker cam within the distributor cap, sequentially connects the coil's secondary windings to one of the several wires leading to each engine's spark plugs. The extremely high voltage from the coil's secondary – often higher than 1000 volts -- causes a spark to form across the gap of the spark plug. This, in turn, ignites the compressed air-fuel mixture within the engine. It is the creation of this spark which consumes the energy that was originally stored in the ignition coil’s magnetic field.

High performance engines with 8 or more cylinders that operate at high r.p.m. as in motor racing that demand higher rate and energy of sparks than the simple ignition circuit can provide may use either of these adaptations:

* Two complete sets of coil, breaker and condenser can be provided for each half of the engine which is arranged in V-8 or V-12 configuration. Although the two ignition system halves are electrically independent, they typically share a single distributor which in this case contains two breakers driven by the rotating cam, and a rotor with two isolated conducting planes for the two high voltage inputs.

* A single breaker driven by a cam and a return spring is limited in spark rate by the onset of contact bounce or float at high rpm. This limit can be overcome by substituting for the breaker a pair of breakers that are connected electrically in parallel but spaced on opposite sides of the cam so they are driven out of phase. Each breaker then switches at half the rate of a single breaker and the "dwell" time for current buildup in the coil is maximised since it is shared between the breakers.

The Lamborghini V-12 engine has both these adaptations and therefore uses two ignition coils and a single distributor that contains 4 contact breakers.

Except that more separate elements are involved, a distributor-based system is not greatly different from a magneto system. There are also advantages to this arrangement. For example, the position of the contact breaker points relative to the engine angle can be changed a small amount dynamically, allowing the ignition timing to be automatically advanced with increasing revolutions per minute (RPM) and/or increased manifold vacuum, giving better efficiency. However it is necessary to check periodically the maximum opening gap of the breaker(s), using a feeler gauge, since this mechanical adjustment affects the "dwell" time during which the coil charges, and breakers should be replaced when they have become pitted by electric arcing.

This system was used almost universally until the late 1970s, when electronic ignition systems started to appear.



Electronic ignition

The disadvantage of the mechanical system is the use of breaker points to interrupt the low voltage high current through the primary winding of the coil; the points are subject to mechanical wear where they ride the cam to open and shut, as well as oxidation and burning at the contact surfaces from the constant sparking. They require regular adjustment to compensate for wear, and the opening of the contact breakers, which is responsible for spark timing, is subject to mechanical variations. In addition, the spark voltage is also dependent on contact effectiveness, and poor sparking can lead to lower engine efficiency. A mechanical contact breaker system cannot control an average ignition current of more than about 3 A while still giving a reasonable service life, and this may limit the power of the spark and ultimate engine speed.

Electronic ignition (EI) solves these problems. In the initial systems, points were still used but they only handled a low current which was used to control the high primary current through a solid state switching system. Soon, however, even these contact breaker points were replaced by an angular sensor of some kind - either optical, where a vaned rotor breaks a light beam, or more commonly using a Hall effect sensor, which responds to a rotating magnet mounted on a suitable shaft. The sensor output is shaped and processed by suitable circuitry, then used to trigger a switching device such as a thyristor, which switches a large flow of current through the coil. The rest of the system (distributor and spark plugs) remains as for the mechanical system. The lack of moving parts compared with the mechanical system leads to greater reliability and longer service intervals. For older cars, it is usually possible to retrofit an EI system in place of the mechanical one. In some cases, a modern distributor will fit into the older engine with no other modifications.

Other innovations are currently available on various cars. In some models, rather than one central coil, there are individual coils on each spark plug. This allows the coil a longer time to accumulate a charge between sparks, and therefore a higher energy spark. A variation on this has each coil handle two plugs, on cylinders which are 360 degrees out of phase (and therefore reach TDC at the same time); in the four cycle engine this means that one plug will be sparking during the end of the exhaust stroke while the other fires at the usual time, a so-called "wasted spark" arrangement which has no drawbacks apart from faster spark plug erosion; the paired cylinders are 1/4 and 2/3. Other systems do away with the distributor as a timing apparatus and use a magnetic crank angle sensor mounted on the crankshaft to trigger the ignition at the proper time.

During the 1980s, EI systems were developed alongside other improvements such as fuel injection systems. After a while it became logical to combine the functions of fuel control and ignition into one electronic system known as an engine management system.



Engine management

In an Engine Management System (EMS), electronics control fuel delivery, ignition timing and firing order. Primary sensors on the system are engine angle (crank or Top Dead Center (TDC) position), airflow into the engine and throttle demand position. The circuitry determines which cylinder needs fuel and how much, opens the requisite injector to deliver it, then causes a spark at the right moment to burn it. Early EMS systems used analogue computer circuit designs to accomplish this, but as embedded systems became fast enough to keep up with the changing inputs at high revolutions, digital systems started to appear.

Some designs using EMS retain the original coil, distributor and spark plugs found on cars throughout history. Other systems dispense with the distributor and coil and use special spark plugs which each contain their own coil (Direct Ignition). This means high voltages are not routed all over the engine, they are created at the point at which they are needed. Such designs offer potentially much greater reliability than conventional arrangements.

Modern EMS systems usually monitor other engine parameters such as temperature and the amount of uncombined oxygen in the exhaust. This allows them to control the engine to minimise unburnt or partially burnt fuel and other noxious gases, leading to much cleaner and more efficient engines.

Ignition system

The ignition system of an internal-combustion engine is an important part of the overall engine system that provides for the timely burning of the fuel mixture within the engine. All conventional petrol (gasoline) engines require an ignition system. The ignition system is usually switched on/off through a lock switch, operated with a key or code patch.


History

The earliest petrol engines used a very crude ignition system. This often took the form of a copper or brass rod which protruded into the cylinder, which was heated using an external source. The fuel would ignite when it came into contact with the rod. Naturally this was very inefficient as the fuel would not be ignited in a controlled manner. This type of arrangement was quickly superseded by spark ignition, attributed to Karl Benz, a system which is generally used to this day, albeit with sparks generated by more advanced circuitry. Early low-speed stationary engines often used a moving contact which protruded into the cylinder. This contact was quickly closed and reopened at the precise instant, producing a spark across the contacts, generated by a coil.



Magneto system

The simplest form of spark ignition is that using a magneto. The engine spins a magnet inside a coil, and also operates a contact breaker, interrupting the current and causing the voltage to be increased sufficiently to jump a small gap. The spark plugs are connected directly from the magneto output. Magnetos are not used in modern cars, but because they generate their own electricity they are often found on piston aircraft engines and small engines such as mopeds, lawnmowers, snowblowers, chainsaws, etc. where there is no battery; also on the small engine's ancestor, the stationary "hit or miss" engine (variously called "hit and miss") of the early twentieth century; on older gasoline or distillate farm tractors before battery starting and lighting became common; and also in aircraft piston engines, where their simplicity and self-contained nature confers a generally greater reliability as well as lighter weight in the absence of a battery and generator or alternator. Aircraft engines usually have multiple magnetos to provide redundancy in the event of a failure. Some older automobiles had both a magneto system and a battery actuated system (see below) running simultaneously to ensure proper ignition under all conditions with the limited performance each system provided at the time.



Switchable systems

The output of a magneto depends on the speed of the engine, and therefore starting can be problematic. Some magnetos incorporate an impulse system, which spins the magnet quickly at the proper moment, facilitating easier starting at slow cranking speeds. Some engines, such as aircraft but also the Ford Model T, utilized a system which relied on non rechargeable dry cells, (like large flashlight batteries, not what are usually thought of as automobile batteries today) to start the engine or for running at low speed; then the operator would manually switch the ignition over to magneto operation for high speed operation. In order to provide high voltage for the spark from the low voltage batteries, however, a "tickler" was used, which was essentially a larger version of the once ubiquitous electric buzzer. With this apparatus, the direct current passes through an electromagnetic coil which pulls open a pair of contact points, interrupting the current; the magnetic field collapses, the spring-loaded points close again, the circuit is reestablished, and the cycle repeats rapidly. The rapidly collapsing magnetic field, however, induces a high voltage across the coil which can only relieve itself by arcing across the contact points; while in the case of the buzzer this is a problem as it causes the points to oxidize and/or weld together, in the case of the ignition system this becomes the source of the high voltage to operate the spark plugs. In this mode of operation, the coil would "buzz" continuously, producing a constant train of sparks. The entire apparatus was known as the Model T spark coil (in contrast to the modern ignition coil which is only the actual coil component of the system), and long after the demise of the Model T as transportation they remained a popular self-contained source of high voltage for electrical home experimenters, appearing in articles in magazines such as Popular Mechanics and projects for school science fairs as late as the early 1960s. In the UK these devices were commonly known as trembler coils and were popular in cars pre-1910, and also in commercial vehicles with large engines until around 1925 to ease starting.

The magneto on the Model T (built into the flywheel) differed from modern implementations by not providing high voltage directly at the output; the maximum voltage produced was about 30 volts, and therefore also had to be run through the spark coil to provide high enough voltage for ignition, as described above, although the coil would not "buzz" continuously in this case, only going through one cycle per spark. In either case, the high voltage was switched to the appropriate spark plug by the timer mounted on the front of the engine, the equivalent of the modern distributor. The timing of the spark was adjustable by rotating this mechanism through a lever mounted on the steering column.


Battery operated ignition

With the universal adaptation of electrical starting for automobiles, and the concomitant availability of a large battery to provide a constant source of electricity, magneto systems were abandoned for systems which interrupted current at battery voltage, used an ignition coil (a type of autotransformer) to step the voltage up to the needs of the ignition, and a distributor to route the ensuing pulse to the correct spark plug at the correct time. The first reliable battery operated ignition was developed by the Dayton Engineering Laboratories Co. (Delco) and introduced in the 1910 Cadillac.

Spark plug

The spark plug is connected the high voltage generated by an ignition coil or magneto. As the electrons flow from the coil, a voltage difference develops between the center electrode and side electrode. No current can flow because the fuel and air in the gap is an insulator, but as the voltage rises further, it begins to change the structure of the gases between the electrodes. Once the voltage exceeds the dielectric strength of the gases, the gases become ionized. The ionized gas becomes a conductor and allow electrons to flow across the gap.

As the current of electrons surges across the gap, it raises the temperature of the spark channel to 60,000 K. The intense heat in the spark channel causes the ionized gas to expand very quickly, like a small explosion. This is the "click" heard when observing a spark, similar to lightning and thunder.

The heat and pressure force the gasses to react with each other, and at the end of the spark event there should be a small ball of fire in the spark gap as the gases burn on their own. The size of this fireball or kernel depends on the exact composition of the mixture between the electrodes and the level of combustion chamber turbulence at the time of the spark. A small kernel will make the engine run as though the ignition timing was retarded, and a large one as though the timing was advanced.


Spark plug construction

A spark plug is composed of a shell, insulator and the conductor. It pierces the wall of the combustion chamber and therefore must also seal the combustion chamber against high pressures and temperatures, without deteriorating over long periods of time and extended use.


Parts of the plug


Terminal

The top of the spark plug contains a terminal to connect to the ignition system. The exact terminal construction varies depending on the use of the spark plug. Most passenger car spark plug wires snap onto the terminal of the plug, but some wires have spade connectors which are fastened onto the plug under a nut. Plugs which are used for these applications often have the end of the terminal serve a double purpose as the nut on a thin threaded shaft so that they can be used for either type of connection. These are a necessary part of the spark plug.


Ribs

By lengthening the surface between the high voltage terminal and the grounded metal case of the spark plug, the physical shape of the ribs functions to improve the electrical insulation and prevent electrical energy from leaking along the insulator surface from the terminal to the metal case. The disrupted and longer path makes the electricity encounter more resistance along the surface of the spark plug even in the presence of dirt and moisture.


Insulator

The insulator is typically made from an aluminium oxide ceramic as is designed to withstand 550° C and 60,000 V. It extends from the metal case into the combustion chamber. The exact composition and length of the insulator partly determines the heat range of the plug.


Seals

As the spark plug also seals the combustion chamber of the engine when installed, the seals ensure there is no leakage from the combustion chamber. The seal is typically made by the use of a multi-layer braze as there are no braze compositions that will wet both the ceramic and metal case and therefore intermediary alloys are required.


Metal case

The metal case of the spark plug bears the torque of tightening the plug, serves to remove heat from the insulator and pass it on to the cylinder head, and acts as the ground for the sparks passing through the center electrode to the side electrode.


Insulator tip

The tip of the insulator surrounding the center electrode is within the combustion chamber and directly affects the spark plug performance, particularly the heat range.


Side electrode, or ground electrode

The side electrode is made from high nickel steel and is welded to the side of the metal case. The side electrode also runs very hot, especially on projected nose plugs. Some spark plug designs use multiple side electrodes that do not overlap the center electrode.



Center electrode

The center electrode is connected to the terminal through an internal wire and commonly a ceramic series resistance to reduce emission of radio noise from the sparking. The tip can be made of a combination of copper, nickel-iron, chromium, or precious metals. The center electrode is usually the one designed to eject the electrons (the cathode) because it is the hottest (normally) part of the plug; it is easier to emit electrons from a hot surface, because of the same physical laws that increase emissions of vapor from hot surfaces (see Thermionic emission). In addition, electrons are emitted where the electrical field strength is greatest; this is from wherever the radius of curvature of the surface is smallest, i.e. from a sharp point or edge rather than a flat surface (see Corona discharge). It would be easiest to pull electrons from a pointed electrode but a pointed electrode would erode after only a few seconds. Instead, the electrons emit from the sharp edges of the end of the electrode; as these edges erode, the spark becomes weaker and less reliable.

At one time it was common to remove the spark plugs, clean deposits off the ends either manually or with specialized sandblasting equipment and file the end of the electrode to restore the sharp edges, but this practice has become less frequent as spark plugs are now merely replaced, at much longer intervals. The development of precious metal high temperature electrodes (using metals such as yttrium, iridium, platinum, tungsten, or palladium, as well as the relatively prosaic silver or gold) allows the use of a smaller center wire, which has sharper edges but will not melt or corrode away. The smaller electrode also absorbs less heat from the spark and initial flame energy. At one point, Firestone marketed plugs with polonium in the tip, under the questionable theory that the radioactivity would ionize the air in the gap, easing spark formation.



Spark plug gap

Spark plugs are typically designed to have a spark gap which can be adjusted by the technician installing the spark plug, by the simple mechanism of bending the ground electrode slightly to bring it closer to or further from the center electrode. The somewhat common belief that plugs are properly gapped as delivered in their box from the factory is incorrect, as proved by the fact that the same plug may be specified for several different engines, requiring a different gap for each. A spark plug gap gauge with round wires of precise diameters is used to measure the gap; use of a feeler gauge with flat blades instead of round wires, as is used on distributor points or valve lash, will give erroneous results, due to the shape of spark plug electrodes. The simplest gauges are a collection of keys of various thicknesses which match the desired gaps and the gap is adjusted until the key fits snugly. With current engine technology, universally incorporating solid state ignitions and computerized fuel injection, the gaps used are much larger than in the era of carburetors and breaker point distributors, to the extent that spark plug gauges from that era are much too small for measuring the gaps of current cars.

This adjustment can be fairly critical and if it is maladjusted the engine may run badly, or not at all. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, while a gap which is too wide may be too wide for a spark to fire at all. Either way, a spark which only intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and fuel efficiency. As the plug ages and the metal of the tip erodes, the gap will tend to widen; therefore experienced mechanics often set the gap on a set of new plugs at the engine manufacturer's minimum recommended gap rather than in the center of the specified acceptable range, to ensure longer life between plug changes. On the other hand, since a larger gap gives a "hotter" or "fatter" spark and more reliable ignition of the fuel-air mixture, and since a new plug with sharp edges on the center electrode will spark more reliably than an older, eroded plug, experienced mechanics also realize that the maximum gap specified by the engine manufacturer is the largest which will spark reliably even with old plugs and will in fact be a bit narrower than necessary to ensure sparking with new plugs; therefore, it is possible to set the plugs to an extremely wide gap for more reliable ignition in high performance applications, at the cost of having to replace and/or regap the plugs much more frequently, as soon as the tip begins to erode.



Variations on the basic design

Over the years variations on the basic spark plug design have attempted to provide either better ignition, longer life, or both. Such variations include the use of two, three, or four equally spaced ground electrodes surrounding the center electrode. Other variations include using a recessed center electrode surrounded by the sparkplug thread, which effectively becomes the ground electrode. Also there is the use of a V-shaped notch in the tip of the ground electrode.



Sealing to the cylinder head

Most spark plugs seal to the cylinder head with a hollow metal washer which is crushed slightly between the flat surface of the head and that of the plug, just above the threads. If the torque used to install the plugs is not excessive, the washer can be reused when the plug is removed and reinserted, although this practice is, strictly speaking, not recommended and replacement washers are available.

Ford engines, however, were once distinct in using a tapered hole and a matching taper on the bottom of the plug above the threads, in order to seal the plug. The torque for installing and removing these plugs was higher and it was easier to break them if the wrench were applied partially off axis.

More recently, some types of Ford Fiesta, and Ka also had a similar sealing system. The torque required to install these plugs is less than with the above type, and it is extremely critical that they not be overtightened, since overtightening can result in it being difficult or impossible to remove them. In addition, they have been known to corrode into the cylinder head, particularly if left in too long between removals. In such a situation, it is not unknown for a plug to snap below the hexagonal nut, leaving just the threaded portion (and the outer electrode) in the cylinder head. Ford has on occasion issued Technical Service Bulletins reminding technicians to use the correct methods of installation.



Tip protrusion

Three different sizes of spark plug. The leftmost plug and center plug are identical in threading, electrodes, tip protrusion, and heat range, and may be used interchangeably; the center plug is, however, a compact variant, with smaller hex and porcelain portions outside the head, to be used where space is limited. The rightmost plug has a longer threaded portion, to be used in a thicker cylinder head
Three different sizes of spark plug. The leftmost plug and center plug are identical in threading, electrodes, tip protrusion, and heat range, and may be used interchangeably; the center plug is, however, a compact variant, with smaller hex and porcelain portions outside the head, to be used where space is limited. The rightmost plug has a longer threaded portion, to be used in a thicker cylinder head

The length of the threaded portion of the plug should be closely matched to the thickness of the head. If a plug extends too far into the combustion chamber, it may be struck by the piston, damaging the engine internally. Less dramatically, if the threads of the plug extend into the combustion chamber, the sharp edges of the threads act as point sources of heat which may cause preignition; in addition, deposits which form between the exposed threads may make it difficult to remove the plugs, even damaging the threads on aluminium heads in the process of removal. The protrusion of the tip into the chamber also affects plug performance, however; the more centrally located the spark gap is, generally the better the ignition of the air-fuel mixture will be, although experts believe the process is actually much more complex and dependent on combustion chamber shape. On the other hand, if an engine is "burning oil", the excess oil leaking into the combustion chamber tends to foul the plug tip and inhibit the spark; in such cases, a plug with less protrusion than the engine would normally call for often collects less fouling and performs better, for a longer period. In fact, special "antifouling" adapters are sold which fit between the plug and the head to reduce the protrusion of the plug for just this reason, on older engines with severe oil burning problems; this will cause the ignition of the fuel-air mixture to be less effective, but in such cases, this is of lesser significance.



Heat range

The operating temperature of a spark plug is the actual physical temperature at the tip of the spark plug within the running engine. This is determined by a number of factors, but primarily the actual temperature within the combustion chamber. There is no direct relationship between the actual operating temperature of the spark plug and spark voltage. However, the level of torque currently being produced by the engine will strongly influence spark plug operating temperature because the maximum temperature and pressure occurs when the engine is operating near peak torque output (torque and RPM directly determine the power output). The temperature of the insulator responds to the thermal conditions it is exposed to in the combustion chamber but not vice versa. If the tip of the spark plug is too hot it can cause pre-ignition leading to detonation/knocking and damage may occur. If it is too cold, electrically conductive deposits may form on the insulator causing a loss of spark energy or the actual shorting-out of the spark current.

A spark plug is said to be "hot" if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be "cold" if it can conduct more heat out of the spark plug tip and lower the tip's temperature. Whether a spark plug is "hot" or "cold" is known as the heat range of the spark plug. The heat range of a spark plug is typically specified as a number, with some manufacturers using ascending numbers for hotter plugs and others doing the opposite, using descending numbers for hotter plugs.

The heat range of a spark plug (i.e. in scientific terms its thermal conductivity characteristics) is affected by the construction of the spark plug: the types of materials used, the length of insulator and the surface area of the plug exposed within the combustion chamber. For normal use, the selection of a spark plug heat range is a balance between keeping the tip hot enough at idle to prevent fouling and cold enough at maximum power to prevent pre-ignition leading to engine knocking. By examining "hotter" and "cooler" spark plugs of the same manufacturer side by side, the principle involved can be very clearly seen; the cooler plugs have more substantial ceramic insulators filling the gap between the center electrode and the shell, effectively carrying off the heat, while the hotter plugs have less ceramic material, so that the tip is more isolated from the body of the plug and retains heat better.

Heat from the combustion chamber escapes through the exhaust gases, the side walls of the cylinder and the spark plug itself. The heat range of a spark plug has only a minute effect on combustion chamber and overall engine temperature. A cold plug will not materially cool down an engine's running temperature. (Too hot of a plug may, however, indirectly lead to a runaway pre-ignition condition that can increase engine temperature.) Rather, the main effect of a "hot" or "cold" plug is to affect the temperature of the tip of the spark plug.

It was common before the modern era of computerized fuel injection to specify at least a couple of different heat ranges for plugs for an automobile engine; a hotter plug for cars which were mostly driven mildly around the city, and a colder plug for sustained high speed highway use. This practice has, however, largely become obsolete now that cars' fuel/air mixtures and cylinder temperatures are maintained within a narrow range, for purposes of limiting emissions. Racing engines, however, still benefit from picking a proper plug heat range. Very old racing engines will sometimes have two sets of plugs, one just for starting and another to be installed once the engine is warmed up, for actually driving the car.



Reading spark plugs

The spark plug's firing end will be affected by the internal environment of the combustion chamber. As the spark plug can be removed for inspection, the effects of combustion on the plug can be examined. An examination, or "reading" of the characteristic markings on the firing end of the spark plug can indicate conditions within the running engine. The spark plug tip will bear the marks as evidence of what is happening inside the engine. Usually there is no other way to know what is going on inside an engine running at peak power. Engine and spark plug manufacturers will publish information about the characteristic markings in spark plug reading charts (e.g. a general spark plug reading chart)

A light brownish discoloration of the tip of the block indicates proper operation; other conditions may indicate malfunction. For example, a sandblasted look to the tip of the spark plug means persistent, light detonation is occurring, often unheard. The damage that is occurring to the tip of the spark plug is also occurring on the inside of the cylinder. Heavy detonation can cause outright breakage of the spark plug insulator and internal engine parts before appearing as sandblasted erosion but is easily heard. As another example, if the plug is too cold, there will be deposits on the nose of the plug. Conversely if the plug is too hot, the porcelain will be porous looking, almost like sugar. The material which seals the center electrode to the insulator will boil out. Sometimes the end of the plug will appear glazed, as the deposits have melted.

An idling engine will have a different impact on the spark plugs than one running at full throttle. Spark plug readings are only valid for the most recent engine operating conditions and running the engine under different conditions may erase or obscure characteristic marks previously left on the spark plugs. Thus, the most valuable information is gathered by running the engine at high speed and full load, immediately cutting the ignition off and stopping without idling or low speed operation and removing the plugs for reading.

Spark plug reading viewers, which are simply combined flashlight/magnifiers, are available to improve the reading of the spark plugs.


Once again, however, the practice of reading spark plugs has largely become obsolete now that cars' fuel/air mixtures and cylinder temperatures are maintained within a narrow range, but is still valuable for racing applications.



Indexing spark plugs

A matter of some debate is the "indexing" of plugs upon installation, usually only for high performance or racing applications; this involves installing them so that the open area of the spark gap, not shrouded by the ground electrode, faces the center of the combustion chamber, towards the intake valve, rather than the wall. Many experts believe that this will maximize the exposure of the fuel-air mixture to the spark, and therefore result in better ignition; others, however, believe that this is useful only to keep the ground electrode out of the way of the piston in ultra-high-compression engines if clearance is insufficient. In any event, this is accomplished by marking the location of the gap on the outside of the plug, installing it, and noting the direction in which the mark faces; then the plug is removed and additional washers are added so as to change the orientation of the tightened plug. This must be done individually for each plug, as the orientation of the gap with respect to the threads of the shell is random.

Diesel cycle

The Diesel cycle is the combustion process of a type of internal combustion engine, in which the burning of the fuel is triggered by the heat generated in first compressing air in the piston cavity, into which is then injected the fuel - as opposed to it being ignited by a spark plug, as combustion is in the Otto cycle (four-stroke/petrol) engine. Diesel engines (heat engines utilizing the Diesel cycle) are used in automobiles, power generation, diesel-electric locomotives, and submarines.



Diesel cycle

The diesel cycle was introduced by Dr. Rudolph Diesel in 1897. In a Diesel cycle engine, heat is supplied (by the burning fuel) while maintaining the cylinder at a constant pressure.

The Diesel cycle generally refers to compression ignition power plants, called the Diesel engine. The engine can be two or four stroke and may draw in air by using the piston or with the aid of an engine-driven supercharger or exhaust gas-driven turbocharger. As the air is compressed it gets hot. When the piston reaches approximately "top dead center", the fuel is injected directly into the cylinder with a high-pressure fuel injector. The fuel ignites immediately; however, as diesel fuel has a higher molecular weight than gasoline, it vaporizes and burns more slowly. The piston is already moving down by the time the combustion starts, and combustion is usually not finished when the piston reaches "bottom dead center." Because of this incomplete combustion, diesel engines actually lose some of the potential energy of the fuel.

Diesel cycle engines are nevertheless more efficient than Otto cycle engines overall, but only when power needs to be scaled. Most land vehicles almost never use the maximum rated power of the engine. Unless the vehicle is at wide open throttle, when the pedal is 'floored', the engine is only producing a fraction of its rated power. Since diesel engines use the heating effect of compressing the air to ignite the fuel, a diesel engine can inject as little or as much fuel as the situation demands. It is important to note that Otto cycle engines can be more efficient than Diesel cycle engines, but only when the engine is running at or near its maximum power. This is dependent on the Otto cycle engine's compression ratio.



General information

The diesel engine has the lowest specific fuel consumption of any large internal combustion engine, 0.26 lb/hp.h (0.16 kg/kWh) for very large marine engines. In fact, two-stroke diesels with high pressure forced induction, particularly turbocharging, make up a large percentage of the very largest diesel engines.

In North America, diesel engines are primarily used in large trucks, where the low-stress, high-efficiency cycle leads to much longer engine life and lower operational costs. These advantages also make the diesel engine ideal for use in the heavy-haul railroad environment.



Other internal combustion engines without spark plugs

Many model airplanes use very simple "glow" and "diesel" engines. Glow engines use glow plugs. "Diesel" model airplane engines have variable compression ratios. Both types depend on special fuels (easily obtainable in such limited quantities) for their ignition timing.

Some 19th century or earlier experimental engines used external flames, exposed by valves, for ignition, but this becomes less attractive with increasing compression. (It was not until Nicolas Léonard Sadi Carnot that the thermodynamic value of compression was known.) An historical implication of this is that the diesel engine would eventually have been invented without the aid of electricity.

Fuel injection in diesel engines

Early fuel injection systems

The modern diesel engine is a combination of two inventors' creations. In all major aspects, it holds true to Diesel's original design, that of the fuel being ignited by compression at an extremely high pressure within the cylinder. However, nearly all present-day diesel engines use the so-called solid injection system invented by Herbert Akroyd Stuart, for his hot bulb engine (a compression-ignition engine that precedes the diesel engine and operates slightly differently). Solid injection is where the fuel is raised to extreme pressures by mechanical pumps and delivered to the combustion chamber by pressure-activated injectors in an almost solid-state jet. Diesel's original engine injected fuel with the assistance of compressed air, which atomised the fuel and forced it into the engine through a nozzle. This is called an air-blast injection. The size of the compressor needed to power such a system made early diesel engines very heavy and large for their power outputs, and the need to drive a compressor lowered power output even more. Early marine diesels often had smaller auxiliary engines whose sole purpose was to drive the compressors to supply air to the main engine's injector system. Such a system was too bulky and inefficient to be used for road-going automotive vehicles.

Solid injection systems are lighter, simpler, and allow for much higher RPMs, and so are universally used for automotive diesel engines. Air-blast systems provide very efficient combustion under low-speed, high-load conditions, especially when running on poor-quality fuels, so some large cathedral marine engines use this injection method. Air-blast injection also raises the fuel temperature during the injection process, so is sometimes known as hot-fuel injection. In contrast, solid injection is sometimes called cold-fuel injection.

Because the vast majority of diesel engines in service today use solid injection, the information below relates to that system.




Mechanical and electronic injection

Older engines make use of a mechanical fuel pump and valve assembly which is driven by the engine crankshaft, usually from the timing belt or chain. These engines use simple injectors which are basically very precise spring-loaded valves which will open and close at a specific fuel pressure. The pump assembly consists of a pump which pressurizes the fuel and a disc-shaped valve which rotates at half crankshaft speed. The valve has a single aperture to the pressurized fuel on one side, and one aperture for each injector on the other. As the engine turns, the valve discs will line up and deliver a burst of pressurized fuel to the injector at the cylinder about to enter its power stroke. The injector valve is forced open by the fuel pressure, and the diesel is injected until the valve rotates out of alignment and the fuel pressure to that injector is cut off. Engine speed is controlled by a third disc, which rotates only a few degrees and is controlled by the throttle lever. This disc alters the width of the aperture through which the fuel passes, and therefore how long the injectors are held open before the fuel supply is cut, which controls the amount of fuel injected.

Older diesel engines with mechanical injection pumps could be inadvertently run in reverse, albeit very inefficiently as witnessed by massive amounts of soot being ejected from the air intake. This was often a consequence of bump starting a vehicle using the wrong gear.

This contrasts with the more modern method of having a separate fuel pump (or set of pumps) which supplies fuel constantly at high pressure to each injector. Each injector then has a solenoid which is operated by an electronic control unit, which enables more accurate control of injector opening times that depend on other control conditions, such as engine speed and loading, resulting in better engine performance and fuel economy. This design is also mechanically simpler than the combined pump and valve design, making it generally more reliable, and less noisy, than its mechanical counterpart.

Both mechanical and electronic injection systems can be used in either direct or indirect injection configurations.




Indirect injection

An indirect injection diesel engine delivers fuel into a chamber off the combustion chamber, called a prechamber, where combustion begins and then spreads into the main combustion chamber, assisted by turbulence created in the chamber. This system allows smoother, quieter running, and because combustion is assisted by turbulence, injector pressures can be lower, which in the days of mechanical injection systems allowed high-speed running suitable for road vehicles (typically up to speed of around 4,000 rpm). The prechamber had the disadvantage of increasing heat loss to the engine's cooling system and restricting the combustion burn, which reduced the efficiency by between 5-10% in comparison to a direct injection engine, and nearly all require some form of cold-start device such as glow plugs. Indirect injection engines were used widely in small-capacity high-speed diesel engines in automotive, marine and construction uses from the 1950s, until direct-injection technology advanced in the 1980s. Indirect injection engines are cheaper to build and it is easier to produce smooth, quiet running vehicles with a simple mechanical system, so such engines are still often used in applications which carry less stringent emissions controls than road-going vehicles, such as small marine engines, generators, tractors, and pumps. With electronic injection systems, indirect injection engines are still used in some road-going vehicles, but most prefer the greater efficiency of direct injection.

During the development of the high-speed diesel engine in the 1930s, various engine manufacturers developed their own type of pre-combustion chamber. Some, such as Mercedes, had complex internal designs. Others, such as the Lanova pre-combustion chamber, used a mechanical system to adjust the shape of the chamber for starting and running conditions. However, the most commonly-used design turned out to be the 'Comet' series of swirl chambers developed by Harry Ricardo, using a two-piece spherical chamber with a narrow 'throat' to induce turbulence. Most European manufacturers of high-speed diesel engines used Comet-type chambers or developed their own versions (Mercedes stayed with their own design for many years), and this trend continues with current indirect-injection engines.



Direct injection

Modern diesel engines make use of one of the following direct injection methods:



Distributor pump direct injection

The first incarnations of direct injection diesels used a rotary pump much like indirect injection diesels; however the injectors were mounted in the top of the combustion chamber rather than in a separate pre-combustion chamber. Examples are vehicles such as the Ford Transit and the Austin Rover Maestro and Montego with their Perkins Prima engine. The problem with these vehicles was the harsh noise that they made and particulate (smoke) emissions. This is the reason that in the main this type of engine was limited to commercial vehicles— the notable exceptions being the Maestro, Montego and Fiat Croma passenger cars. Fuel consumption was about fifteen to twenty percent lower than indirect injection diesels, which for some buyers was enough to compensate for the extra noise.

One of the first small-capacity, mass-produced direct-injection engines that could be called refined was developed by the Rover Group.[citation needed] The '200Tdi' 2.5-litre 4-cylinder turbo diesel (of 111 horsepower) was used by Land Rover in their vehicles from 1989, and the engine used an aluminum cylinder head, Bosch two-stage injection and multi-phase glow plugs to produce a smooth-running and economical engine while still using mechanical fuel injection.

This type of engine was transformed by electronic control of the injection pump, pioneered by Volkswagen Audi group with the Audi 100 TDI introduced in 1989. The injection pressure was still only around 300 bar, but the injection timing, fuel quantity, exhaust gas recirculation and turbo boost were all electronically controlled. This gave much more precise control of these parameters which made refinement much more acceptable and emissions acceptably low. Fairly quickly the technology trickled down to more mass market vehicles such as the Mark 3 Golf TDI where it proved to be very popular. These cars were both more economical and more powerful than indirect injection competitors of their day.



Common rail direct injection

In older diesel engines, a distributor-type injection pump, regulated by the engine, supplies bursts of fuel to injectors which are simply nozzles through which the diesel is sprayed into the engine's combustion chamber.

In common rail systems, the distributor injection pump is eliminated. Instead an extremely high pressure pump stores a reservoir of fuel at high pressure - up to 1,800 bar (180 MPa, 26,000 psi) - in a "common rail", basically a tube which in turn branches off to computer-controlled injector valves, each of which contains a precision-machined nozzle and a plunger driven by a solenoid, or even by piezo-electric actuators, which are found on experimental diesel race car engines.

Most European automakers have common rail diesels in their model lineups, even for commercial vehicles. Some Japanese manufacturers, such as Toyota, Nissan and recently Honda, have also developed common rail diesel engines.

Different car makers refer to their common rail engines by different names, e.g. DaimlerChrysler's CDI, Ford Motor Company's TDCi (most of these engines are manufactured by PSA), Fiat Group's (Fiat, Alfa Romeo and Lancia) JTD, Renault's dCi, GM/Opel's CDTi (most of these engines are manufactured by Fiat, other by Isuzu), Hyundai's CRDi, Mitsubishi's DI-D, PSA Peugeot Citroën's HDi (Engines for commercial diesel vehicles are made by Ford Motor Company), Toyota's D-4D, and so on.



Unit direct injection

Unit direct injection also injects fuel directly into the cylinder of the engine. However, in this system the injector and the pump are combined into one unit positioned over each cylinder. Each cylinder thus has its own pump, feeding its own injector, which prevents pressure fluctuations and allows more consistent injection to be achieved. This type of injection system, also developed by Bosch, is used by Volkswagen AG in cars (where it is called a Pumpe-Düse-System - literally "pump-nozzle system") and by Mercedes Benz (PLD) and most major diesel engine manufacturers in large commercial engines (CAT, Cummins, Detroit Diesel). With recent advancements, the pump pressure has been raised to 2,050 bar (205 MPa), allowing injection parameters similar to common rail systems.



Hypodermic injection injury hazard

Because many diesel engine fuel injection systems operate at extremely high pressure, there is a risk of injury by hypodermic injection of fuel, if the fuel injector is removed from its seat and operated in open air.

How diesel engines work

When a gas is compressed, its temperature rises (see the combined gas law); a diesel engine uses this property to ignite the fuel. Air is drawn into the cylinder of a diesel engine and is compressed by the moving piston at a compression ratio as high as 25:1, much higher than needed for a spark-ignition engine. At the end of the piston stroke, diesel fuel is injected into the combustion chamber at high pressure through an atomising nozzle. The fuel ignites directly from contact with the air, the temperature of which reaches 700–900 °C (1300–1650 °F). The combustion causes the gas in the chamber to heat up rapidly, which increases its pressure, which in turn forces the piston outward. The connecting rod transmits this motion to the crankshaft, which delivers rotary power at its output end. Scavenging (pushing the exhausted gas-charge out of the cylinder and drawing in a fresh draught of air) of the engine is done either by ports or valves. To significantly increase the efficiency of a diesel engine, a turbocharger to compress the intake air is often used. Use of an aftercooler/intercooler to cool the intake air after compression by the turbocharger further improves efficiency.

In cold weather, diesel engines can be difficult to start because the cold metal of the cylinder block and head draw out the heat created in the cylinder during the compression stroke, thus preventing ignition. Most Diesel engines use small electric heaters called glow plugs inside the cylinder to warm the cylinders prior to starting. Some even use resistive grid heaters in the intake manifold to warm the inlet air until the engine reaches operating temperature. Engine block heaters (electric resistive heaters in the engine block) plugged into the utility grid are often used when an engine is shut down for extended periods (more than an hour) in cold weather to reduce startup time and engine wear. Diesel fuel is also prone to 'waxing' in cold weather. This is when the fuel begins to solidify into a crystaline state. The crystals build up in the fuel system (especially the fuel filters), eventually starving the engine of fuel. Low-output electric heaters in fuel tanks and around fuel lines are used to solve this problem. Also, most engines have a 'spill return' system, by which any excess fuel from the injector pump and injectors is returned to the fuel tank. Once the engine is warmed up, this warm fuel will prevent waxing in the tank. Fuel technology has improved in recent years, with special additives preventing waxing in all but the coldest climates.

A vital component of older diesel engine systems is the governor, which limits the speed of the engine by controlling the rate of fuel delivery. Unlike in petrol (gasoline) engines, incoming air is not throttled and an engine without a governor can overspeed. Older injection systems were driven by a gear system from the engine and thus supplied fuel in proportion with engine speed. Modern, electronically controlled engines apply controls similar to those of petrol engines and limit the maximum RPM through an electronic control module (ECM) or electronic control unit (ECU)—the engine-mounted computer. The ECM/ECU receives an engine speed signal from a sensor and controls the amount of fuel and (start of injection) timing through electric or hydraulic actuators.

Controlling the timing of the start of injection of fuel into the cylinder is a key to minimizing emissions, and maximizing fuel economy (efficiency), of the engine. The timing is usually measured in units of crank angle of the piston before Top Dead Center (TDC). For example, if the ECM/ECU initiates fuel injection when the piston is 10 degrees before TDC, the start of injection, or timing, is said to be 10 deg BTDC. Optimal timing will depend on the engine design as well as its speed and load.

Advancing the start of injection (injecting before the piston reaches TDC) results in higher in-cylinder pressure and temperature, and higher efficiency, but also results in higher emissions of oxides of nitrogen (NOx) because of the higher temperatures. At the other extreme, delayed start of injection causes incomplete combustion. This results in higher particulate matter (PM) and unburned hydrocarbon (HC) emissions and more smoke.

Diesel engine and history

The steam engine is a type of internal combustion engine. It is a compression ignition engine, in which the fuel ignites as it is injected into the engine. By contrast, in the gasoline engine the fuel is mixed first and then ignited by a spark plug. Also, diesels generally have high compression ratios, to enable compression ignition, whereas in gasoline-burning engines, compression ignition is undesirable.

The engine operates using the diesel cycle.

The engine is named after German engineer Rudolf Diesel, who invented it in 1892 based on the hot bulb engine and received the patent on February 23, 1893. Diesel intended the engine to use a variety of fuels including coal dust and peanut oil. He demonstrated it at the 1900 Exposition Universelle (World's Fair) using peanut oil.



Early history timeline

* 1862: Nicolaus Otto develops his coal gas engine, similar to a modern gasoline engine.

* 1891: Herbert Akroyd Stuart, of Bletchley perfects his oil engine, and leases rights to Hornsby of England to build engines. They build the first cold start, compression ignition engines.

* 1892: Hornsby engine No. 101 is built and installed in a waterworks. It is now in the MAN truck museum in Northern England.

* 1892: Rudolf Diesel develops his Carnot heat engine type motor which burnt powdered coal dust. He is employed by refrigeration genius Carl von Linde, then Munich iron manufacturer MAN AG, and later by the Sulzer engine company of Switzerland. He borrows ideas from them and leaves a legacy with all firms.

* 1892: John Froelich builds his first oil engine powered farm tractor.

* 1894: Witte, Reid, and Fairbanks start building oil engines with a variety of ignition systems.

* 1896: Hornsby builds diesel tractors and railway engines.

* 1897: Winton produces and drives the first US built gas automobile; he later builds diesel plants.

* 1897: Mirrlees, Watson & Yaryan build the first British diesel engine under license from Rudolf Diesel. This is now displayed in the Science Museum at South Kensington, London.

* 1898: Busch installs a Rudolf Diesel type engine in his brewery in St. Louis. It is the first in the United States. Rudolf Diesel perfects his compression start engine, patents, and licences it. This engine, pictured above, is in a German museum.

* 1899: Diesel licences his engine to builders Burmeister & Wain, Krupp, and Sulzer, who become famous builders.

* 1902: F. Rundlof invents the two-stroke crankcase, scavenged hot bulb engine.

* 1902: A company named Forest City [1] start manufacturing diesel generators.

* 1903: Ship Gjoa transits the ice-filled Northwest Passage, aided with a Dan kerosene engine.

* 1904: French build the first diesel submarine, the Z.

* 1908: Bolinder-Munktell starts building two stroke hot-bulb engines.

* 1912: First diesel ship MS Selandia is built. SS Fram, polar explorer Amundsen’s flagship, is converted to a AB Atlas diesel.

* 1913: Fairbanks Morse starts building its Y model semi-diesel engine. US Navy submarines use NELSECO units.

* 1914: German U-Boats are powered by MAN diesels. War service proves engine's reliability.

* 1920s: Fishing fleets convert to oil engines. Atlas-Imperial of Oakland, Union, and Lister diesels appear.

* 1924: First diesel trucks appear.

* 1928: Canadian National Railways employ a diesel shunter in their yards.

* 1930s: Clessie Cummins starts with Dutch diesel engines, and then builds his own into trucks and a Duesenberg luxury car at the Daytona speedway.

* 1930s: Caterpillar starts building diesels for their tractors.

* 1933: Citroën introduced the Rosalie, a passenger car with the world’s first commercially available diesel engine developed with Harry Ricardo.

* 1934: General Motors starts a GM diesel research facility. It builds diesel railroad engines—The Pioneer Zephyr—and goes on to found the General Motors Electro-Motive Division, which becomes important building engines for landing craft and tanks in the Second World War. GM then applies this knowledge to market control with its famous Green Leakers for buses and railroad engines.

* 1936: Mercedes-Benz builds the 260D diesel car. A.T.S.F inaugurates the diesel train Super Chief.

* 1936: Airship Hindenburg is powered by diesel engines.

Oldsmobile V8 engine Generation 2

The second generation of Oldsmobile V8s was produced from 1964 through 1990. Most of these engines were very similar, using the same bore centers, although "big-block" versions were produced with a 10.625 in (269.9 mm) deck height rather than 9.33 in (237 mm). Big-block and Diesel versions also used a larger 3.0 in (76.2 mm) instead of 2.5 in (63.5 mm) main journal for increased strength. All generation-2 small-block Olds V8s use a stroke of 3.385 in (86 mm), and all but one big-block use 4.25 in (107.9 mm).

These engines, while being a wedge-head, had a unique combustion chamber that resulted from a valve angle of only 6°. This was much flatter than the 23° of the small-block Chevrolet and 20° of the Ford small-block wedge heads. This very open and flat chamber was fuel efficient and had lower than average emissions output. It was the only GM engine to meet US emission standards using a carburetor all the way up to 1990.



330

The first second-generation Olds V8 was the 1964 330 in³ (5.4 L). It introduced the standard 3.385 in (86 mm) stroke and used a 3.938 in (100 mm) bore and was produced through 1967. 330s were painted gold and had forged steel crankshafts. While the 4 barrel versions had a harmonic balancer, the 2 barrel versions had only a hub.



Jetfire Rocket

For 1967, a 330 in³ (5.4 L) Jetfire Rocket was produced.



400

The 400 in³ (6.6 L) version was the second tall-deck "big-block" Olds. Two 400 versions were made:

* 1965 through 1967 Early 400s used a slightly over-square 4.0 in (101.6 mm) bore and 3.98 in (101.1 mm) stroke. This was the desirable 400.

* 1968 and 1969 400s shared the Olds big-block standard 4.25 in (107.9 mm) stroke with the 455 but used a very undersquare 3.87 in (98.3 mm) bore to comply with GM's displacement restrictions in the A-body cars and reduce tooling costs. This was the less desirable Later 400. Early 400's used the same forged steel crankshaft as the 425's, while the Later 400's used the same cast iron crankshaft of the 455's.

All 400s were painted bronze.



4-4-2 Rocket

The 1967 4-4-2 Rocket was a 400 in³ (6.6 L) V8.



425

The 425 in³ (7.0 L) big-block was the first tall-deck, "big block" produced from 1965 through 1967. It is arguably the best engine Olds made in the musclecar era, although it never made it into a "musclecar". It used a 4.126 in (104.8 mm) bore and 3.975 in (101 mm) stroke. Most 425s were painted red. All 425 engines had forged steel crankshafts with harmonic balancers.



Super Rocket

The standard 1965-1967 425 in³ (7.0 L) was called the Super Rocket, and was the most powerful engine option for the Oldsmobile 88 & 98 of 1965 through 1967. Compression ratios of 9 to 1 or 10.25 to 1 were available in the U.S.



Starfire

A special 1965-1967 425 in³ (7.0 L) V8 was the Starfire engine. The main distinguishing features of this engine were a slightly different camshaft profile from the standard ultra high compression engine and factory dual exhaust. This engine was only available in the Oldsmobile Starfire. It shared the same compression ratio of the Toronado Rocket at 10.5 to 1. It also used the .921 in lifter bore size of the Toronado Rocket.



Toronado Rocket

Another 1967 425 in³ (7.0 L) was the Ultra High Compression Toronado Rocket. Unlike all other 425s, this version was painted slate blue metallic. The Toronado 425 engines had the same .921 in (23.4 mm) diameter lifters of the first-generation Oldsmobile engines rather than the standard .842 in (21.4 mm). This let the engineers increase the ramp speed of the camshaft for more power, 385 hp (287 kW), without sacrificing idle or reliability.



455

A larger big-block was introduced for 1968 as the Rocket 455 at 455 in³ (7.5 L) to replace the 425s. It kept the 425's 4.126 in (104.8 mm) bore and bumped the stroke to 4.25 in (107.9 mm). 1968-1969 455s were painted red, while 1970-1976 versions were metallic blue. The "Rocket" name disappeared from the air cleaner identification decal after 1974. Although production of the 455 ended in 1976, a small number were produced through 1978 for power equipment use. Output ranged from 275 to 400 hp (156 to 298 kW).

Applications:

* Oldsmobile Cutlass
* Oldsmobile Vista Cruiser
* Oldsmobile 442
* Oldsmobile Delta 88
* Oldsmobile 98
* 1968-1970 Oldsmobile Toronado, 375 hp
* 1968-1970 Oldsmobile Toronado GT (W34), 400 hp



350

Produced from 1968 through 1980, the Rocket 350 was entirely different from the other GM divsions 350's. It used a 4.057 in (103 mm) bore and Oldsmobile small-block standard 3.385 in (86 mm) stroke for 350 in³ (5.7 L). 1968-1974 350s were painted gold, while 1975-1980 models were metallic blue, at which time the "Rocket" name disappeared from the air cleaner decal. Output ranged from 160 to 320 hp (119 to 238 kW). All Oldsmobile 350 engines had cast-iron crankshafts with harmonic balancers.

The Oldsmobile 350 was also produced with an electronic port fuel injection system, introduced in the Cadillac Seville of 1976.

Applications:

* Cadillac Seville
* Oldsmobile Cutlass
* Oldsmobile Vista Cruiser
* Oldsmobile 442
* Oldsmobile Delta 88
* Oldsmobile 98
* Oldsmobile Toronado
* Oldsmobile Omega



L34

Oldsmobile's own L34 350 in³ (5.7 L) V8 was used in the 1976-1980 Hurst/Olds models. The L34 used a 4-barrel carburetor.



LF9

The LF9 was a Diesel version of the 350 in³ (5.7 L) V8. It was produced from 1978 to 1985 and was used by most domestic GM marques. 1980-1985 versions used roller lifters. These engines were notably unreliable, a situation detailed below, and at the Oldsmobile Diesel V6 engine page.



Oldsmobile Diesel problems

Despite the fact that these engines looked in large part like their gasoline cousins, they were indeed quite different. The castings were much thicker and heavier, and a higher quality alloy was used for the block and heads. The main bearing journals were also increased to 3.000 inches in size to compensate for the higher operating stresses and pressures that diesels exert on their reciprocating parts. The primary problem with GM's Diesel engines of the 1970s was due in large part to poor fuel quality (diesel fuel was notoriously filthy and contaminated with water in the late 1970's), which caused corrosion in the fuel injection pump. This corrosion could (and often did) cause an incorrect injection cycle, which would produce abnormally high cylinder pressures. This in turn would cause the cylinder head to "lift" up off of the block, and stretch (or even break) the head bolts. Once the head gasket was compromised, the gasket would leak coolant into the cylinder. At 22.5:1 compression, there was little volume left in the cylinder at TDC. The uncompressible quality of liquids means that the engine would hydro lock, breaking pistons, crankshafts, connecting rods, and other parts, resulting in complete and catastrophic engine damage. Why then, did other Diesel engines, from GM and other companies, not have these problems? The answer lies in the lack of an effective water separating system, such as can be found on other diesel applications. Overall, the main ingredients of disaster that affected this engine lie in: 1) A poorly designed fuel system, which was fostered by a desire to insulate the consumer from the unpleasant aspects of Diesel ownership. 2) A misguided attempt to market the diesel engine as if it was as convenient to operate and maintain as a gasoline engine. 3) A poorly trained service staff which often used the incorrect oils and service procedures for this (and any, for that matter) Diesel engine. These factors combined to create the ultimate downfall of this engine. In the hands of an experienced diesel operator, these engines can (and often do) travel for hundreds of thousands of trouble free miles. However, for owners who would just "gas and go", this engine was particularly ill suited to the task.



403

The 455 big-block Olds V8 was replaced in 1977 with the 403 in³ (6.6 L). It used a wide 4.351 in (110.5 mm) bore, the largest ever used in a small-block V8, with the Olds small-block standard deck and 3.385 in (86 mm) stroke. The bore was so wide that it was "siamesed" (similar to the Chevrolet 400 small block motor) — there was no space for coolant flow between the cylinders. This sometimes led to overheating problems. Like the 455, it was painted metallic blue.

The Olds 403 was used by Buick and Pontiac in addition to Oldsmobile. The engine was only produced through 1979. Output was 185 hp (137 kW) and 320 ft·lbf (433 N·m).

Applications:

* 1977-79 Buick Riviera
* 1977-79 Buick Electra/Park Avenue
* 1977-79 Buick Estate Wagon
* 1977 Oldsmobile Cutlass
* 1977 Oldsmobile Vista Cruiser
* 1977 Pontiac Bonneville
* 1977-1978 Oldsmobile Delta 88
* 1977-1978 Oldsmobile Toronado
* 1977-1979 Oldsmobile 98
* 1977-1979 Oldsmobile Custom Cruiser
* 1977-1979 Pontiac Trans Am
* 1977 Grand Prix available with California Emissions Only
* 1977-1979 GMC Motor Homes



260

A smaller 260 in³ (4.3 L) V8 was produced in 1975 by decreasing the bore to just 3.5 in (88.9 mm). This was the first powerplant to use the Rochester Dualjet carburetor; all 260s used this small two-barrel carburetor. Production of the 260 V8 ended in 1982 when the 307 became the only gasoline V8 engine in Oldsmobile's line.

The 260 engine was designed for economy and it was the first engine option above the 3.8 V6 Buick engine that had been made standard in many Oldmobile models by the late 1970's. While the 260 engines were not very powerful compared to the larger 350 and 403 V8 engines, fuel economy was almost as good as the base V6. Compared to the V6, the 260 was also smoother-running, and far more durable.

Most 260s were coupled to the unreliable Turbo Hydramatic 200 transmission as opposed to the THM350 coupled behind the Buick 3.8. A 5-speed manual transmission was also available with some 260-equipped vehicles.

Applications:

* 1975-77 Pontiac Ventura, Oldsmobile Omega, and Buick Skylark
* 1975-82 Oldsmobile Cutlass
* 1978-82 Buick Regal



LV8

The LV8 was a 260 in³ (4.3 L) version produced from 1975 to 1982. It produced just 105 hp (78 kW) and 205 ft·lbf (283 N·m).



LF7

The LF7 was a Diesel version of the 260 in³ (4.3 L) V8 produced in 1979 and 1980. Output was just 90 hp (67 kW) and 170 ft·lbf (230 N·m). These engines were notably unreliable, a situation detailed at the Oldsmobile Diesel V6 engine page.



307

A slightly larger 307 in³ (5 L) version was introduced in 1980. It uses the Oldsmobile 3.385 in (86 mm) stroke with a 3.8 in (96.5 mm) bore. All 307s were painted black. It was used in most Oldsmobile models, as well as those from Buick, Cadillac, Chevrolet, and Pontiac. Every 307 was carbureted, and all used 4-barrel carbs. In fact, the 1990 5.0 L Olds V8 was the last carbureted passenger car engine on the market in the United States (excluding the 1991 Ford LTD Crown Victoria Police Interceptor 351 in³ and the 1994 Mazda pick up truck, the very last carbureted road use vehicle sold in the US).

Applications:

* 1980-1985 Oldsmobile Delta 88
* 1980-1984 Oldsmobile 98
* 1980-1985 Oldsmobile Toronado
* 1980-1990 Oldsmobile Custom Cruiser
* 1980-1985 Buick Lesabre
* 1980-1984 Buick Electra
* 1980-1985 Buick Riviera
* 1980-1990 Buick Estate Wagon
* 1986-1990 Cadillac Brougham
* 1986-1990 Chevrolet Caprice Wagon



LV2

Oldsmobile used the popular LV2, a 307 in³ (5.0 L) engine, from 1980 to 1990. It was used by every domestic GM automobile marque. Roller lifters were added in 1985.

There were two versions, the standard Y version produced just 140 hp to 150 hp (104 to 111 kW). The high-output 9 version was available in the 1983 and 1984 Hurst/Olds & 442. All LV2s feature a 4-barrel carburetor.

Y-version applications:

* 1980-1985 Buick Lesabre
* 1980-1985 Buick Riviera
* 1986-1990 Chevrolet Caprice
* 1980-1985 Oldsmobile Delta 88
* 1980-1984 Oldsmobile 98
* 1980-1985 Oldsmobile Toronado
* 1980-1990 Oldsmobile Custom Cruiser
* 1980-1981 Oldsmobile Cutlass
* 1982-1988 Oldsmobile Cutlass Supreme

9-version applications:

* 1983-1984 Hurst/Olds
* 1983-1984 Oldsmobile 442
* 1986-1990 Cadillac Brougham



LG8

The LG8 was a modern 307 in³ 5.0 L High-Output derivative of the LV2 produced from 1985 to 1987. Performance modifications included improved intake and a "hot" camshaft. It was offered in the 442 version of the Oldsmobile Cutlass Supreme. Output for the first year was 180 hp (134 kW) and 245 ft·lbf (318 N·m). The addition of roller lifters for 1986 increased torque to 255 ft·lbf (332 N·m), while lowering the RPM at which peak horsepower and torque was achieved via a change in head design.

Applications:

* 1985-1987 Oldsmobile 442
* 1985-1988 Cadillac Sedan Deville Brougham w/ Vin 9

Oldsmobile V8 engine Generation 1

The first generation of Oldsmobile V8s ranges from 1949 until 1964. Each engine in this generation is quite similar with the same size block and heads.



303

The 303 in³ (5.0 L) engine had hydraulic lifters, an oversquare bore:stroke ratio, a counterweighted forged crankshaft, aluminum pistons, floating wristpins, and a dual-plane intake manifold. The 303 was produced from 1949 until 1953. Bore was 3.75 in (95.2 mm) and stroke was 3.4375 in (87.3 mm). Cadillac also used this engine design in the early 1950s.

The original Oldsmobile V8 was originally to be advertised as "Kettering Power" after chief engineer Charles Kettering, but company policy disallowed the use of his name. So the engine was sold as the Oldsmobile Rocket. The engine was available in Oldsmobile's 88 and Super 88 models, which acquired the nickname Rocket 88

The 303 was available from 1949 through 1953. 1949 through 1951 "88" 303's came with a 2-barrel carburetor for 135 hp (100 kW) and 253 ft·lbf (343 N·m). 1952 88 and Super 88 V8s used a 4-barrel carb for 160 hp (119 kW) and 265 ft·lbf (359 N·m), while 1953 versions upped the compression from 7.5:1 to 8.0:1 for 165 hp (123 kW) and 275 ft·lbf (372 N·m). For comparison, a 1949 Ford Flathead V8 produced just 100 hp (74 kW).

Applications:

* 1949-1953 Oldsmobile 88
* 1949-1953 Oldsmobile 98
* 1952 Oldsmobile Super 88



324

The 324 in³ (5.3 L) version was also produced from 1954 until 1956. Bore was increased to 3.875 in (98.4 mm) and stroke remained the same at 3.4375 in (87.3 mm). All high performance 324s came with 4-barrel carburetors. The 324 was shared with GMC trucks.

1954 88 and Super 88 V8s used an 8.25:1 compression ratio for 170 and 185 hp (126 and 137 kW) and 295 and 300 ft·lbf (399 and 406 N·m) respectively. 1955 upped the compression to 8.5:1 for 185 hp (137 kW) and 320 ft·lbf (433 N·m) in the 88 and 202 hp (150 kW) and 332 ft·lbf (450 N·m) in the Super 88 and 98. Compression was up again in 1956 for 230 hp (171 kW) and 340 ft·lbf (460 N·m) in the 88 and 240 hp (178 kW) and 350 ft·lbf (474 N·m) in the Super 88 and 98.

Applications:

* 1954-1956 Oldsmobile 88
* 1954-1956 Oldsmobile Super 88
* 1954-1956 Oldsmobile 98



370

A special 370 in³ (6.1 L) variant called the 370 was used in GMC trucks alone, not shared.



371

371s were produced from 1957 through 1963. Bore was now 4.0 in (101.6 mm) and stroke was increased to 3.6875 in (93.7 mm) for 371 in³ (6.1 L). 1959 and 1960 371s used green painted valve covers. 4-barrel models used 9.25:1 compression in 1957 and 10:1 in 1958 for 277 hp (206 kW) and 400 ft·lbf (542 N·m) and 305 hp (227 kW) and 410 ft·lbf (555 N·m) respectively. A 1958 2-barrel version was still impressive at 265 hp (197 kW) and 390 ft·lbf (528 N·m), but power nosed downward for the 1959 and 1960 88 model: 270 hp (201 kW) and 390 ft·lbf (528 N·m) for 1959 and 240 hp (178 kW) and 375 ft·lbf (508 N·m) for 1960.

The 371 was also used in GMC trucks.

Applications:

* 1957-1960 Oldsmobile 88
* 1957-1958 Oldsmobile Super 88
* 1957-1958 Oldsmobile 98



J-2 Golden Rocket

The 1957 and 1958 J-2 Golden Rocket produced 312 hp (232 kW) and 415 ft·lbf (562 N·m) with a tri-power six-barrel carburetor.



394

Bore was up to 4.125 in (104.8 mm) for the largest first-generation Rocket, the 394 in³ (6.5 L). 394s were produced from 1959 through 1964 and were available on many Olds models. Most 394s used 2-barrel carburetors.

The 394 replaced the 371 in Super 88 and 98 cars for 1959 and 1960 and a detuned version was used in the 88 for 1961 and the Dynamic 88 for 1962 through 1964.

Applications:

* 1959-1960 Oldsmobile Super 88, 315 hp (234 kW) and 435 ft·lbf (589 N·m)
* 1959-1960 Oldsmobile 98, 315 hp (234 kW) and 435 ft·lbf (589 N·m)
* 1961 Oldsmobile 88, 250 hp (186 kW) and 405 ft·lbf (549 N·m)
* 1962-1964 Oldsmobile Dynamic 88, 280 hp (208 kW) and 430 ft·lbf (582 N·m)
* 1964 Oldsmobile Jetstar I, 345 hp (257 kW) and 440 ft·lbf (596 N·m)



Sky Rocket

The 1961 through 1963 Sky Rocket (and 1964 Rocket) was a 394 in³ (6.5 L) engine. The 10:1 compression 1961 model produced 325 hp (242 kW) and 435 ft·lbf (589 N·m), while the 10.25:1 1962-1964 version upped power to 330 hp (246 kW) and 440 ft·lbf (596 N·m). A special 1963 10.5:1 version was also produced with 345 hp (257 kW).

Applications:

* 1961-1963 Oldsmobile Dynamic 88 (option)
* 1961-1964 Oldsmobile Super 88 (standard)
* 1961-1964 Oldsmobile 98 (standard)



Starfire

The 1964 Starfire produced 345 hp (257 kW) and 440 ft·lbf (596 N·m) for the 1964 98 Custom-Sports Coupe. It was optional on 1964 98s and Super 88s.



Aluminum 215 ("Rockette")

From 1961 to 1963 Oldsmobile manufactured its own version of the Buick-designed, all-aluminum 215 engine for the F-85 compact, known as the Rockette. This was a compact, lightweight engine with a dry weight of only 350 lb (159 kg). The Oldsmobile engine was very similar to the Buick engine, but not identical: it had larger combustion chambers with flat-topped (rather than domed) pistons, six bolts rather than five per cylinder head, and slighly larger intake valves. With an 8.75:1 compression ratio and a two-barrel carburetor, the Olds 215 had the same rated hp, 155 hp @ 4800 rpm, as the Buick 215, with 220 ft·lbf of torque at 2400 rpm. With a four-barrel carburetor and 10.25:1 compression, the Olds 215 made 185 hp (138 kW) @ 4800 rpm and 230 ft·lbf (312 N·m) (@ 3200 rpm.

The basic Buick/Olds 215 V8 went onto become the well known Rover V8, remaining in production until the 1990s.



Turbo Jetfire

In 1962 and 1963 Oldsmobile built a turbocharged version of the 215. The small-diameter turbocharger was manufactured by Garrett AiResearch and produced a maximum of 5 lb (0.34 bar) boost at 2200 rpm. The engine had 10.25:1 compression and a single-barrel carburetor. It was rated at 215 hp (160 kW) @ 4600 rpm and 300 ft·lbf (406 N·m) @ 3200 rpm. The high compression ratio created a serious problem with spark knock on hard throttle applications, which led Olds to use a novel water-injection system that sprayed small amounts of distilled water and methyl alcohol (dubbed "Turbo-Rocket Fluid") into the combustion chambers to cool the intake charge. If the fluid reservoir was empty, the engine's timing would be retarded to avoid engine damage. Unfortunately, many customers did not keep the reservoir filled, or had mechanical problems with the turbocharger plumbing.

The turbocharger was offered only in a special Jetfire model, which was the first turbocharged passenger car offered for public sale. Only 9,607 were sold in two model years, and many were converted by dealers to conventional four-barrel carbureted form.

Oldsmobile V8 engine

The Oldsmobile Rocket V8 was the first post-war OHV V8 at General Motors. Production started in 1949, with a new generation introduced in 1964. Like Pontiac, Olds continued building its own V8 engine family for decades, finally adopting the corporate Chevrolet 350 small-block and Cadillac Northstar engine only in the 1990s.

All Oldsmobile V8s use a 90° bank angle, and most share a common stroke dimension: 3.4375 in (87.3 mm) for early Rockets, 3.6875 in (93.7 mm) for later Generation 1 motors, and 3.385 in (86 mm) for Generation 2. The engine could be classified as a small-block, but Oldsmobile used a higher deck height for a 4.25 in (107.9 mm) stroke to boost displacement to a big-block-like 455 in³ (7.5 L).

The Rocket V8 was the subject of many first and lasts in the automotive industry. It was the first mass-produced OHV V8 in 1949; and was the last carbureted V8 passenger car engine in 1990.

Toyota T engine

The Toyota T series is a family of inline-4 automobile engines manufactured by Toyota starting in 1970 and ending in 1985. It started as a Push Rod Overhead Valve(OHV) design and later, performance oriented Dual Overhead Cam(DOHC) variants were added to the lineup. Toyota had built its solid reputation on the reliability of these engines.

The 4T-GTE variant of this engine allowed Toyota to compete in the World Rally Championship in the early 1980s, making it the first Japanese manufacturer to do so.

The bottom end of the Toyota 503 Race engine is patterned after the 3T engine. Race engines based on the 2T-G include the 100E, 151E.

* All T engines utilize a timing chain and have a cast iron block with an alloy cylinder head with hardened valve seats and a hemispherical combustion chamber design (HEMI)..

* All T engines are carburated except those with electronic fuel injection, "E" designation.

* All T engines use a 2 valve OHV design except those with a DOHC performance head, "G" designation.

* The 12T/13T has a sub-cylinder directly behind the spark plug that leads into a smaller chamber for emission purposes.

The Toyota T engine series was later replaced by the Toyota A engine series.



T-(B) (1.4L)

The first T engine displaced 1407 cc and was produced from 1970 through 1979. Cylinder bore is 80 mm (3.15 in) and stroke is 70 mm (2.76 in).

Output is 86 hp (64 kW) at 6000 RPM and 85 ft·lbf (115 N·m) at 3800 RPM. The more-powerful twin-carburetor T-B was produced for the first six years.

Applications:

* Toyota Corolla E20 series



2T-(B/C/U) (1.6L)

The larger 1588 cc 2T was produced from 1970 through 1984. Cylinder bore is 85 mm (3.35 in) and stroke is 70 mm (2.76 in).

The 2T engines are usually coupled with either a T40 4 speed/T50 5 speed manual transmission, or an A40 4 speed automatic transmission.

Output for the early 2T-C bigport design is 102hp, while the basic version is 75 hp (56 kW) at 5200 RPM and 87 ft.lbf (117 Nm) at 3600 RPM. The twin-carb 2T-B produces 90-105 hp (67-78 kW) and 85-102 ft·lbf (115-138 N·m). California emissions dropped output to 75 hp (56 kW) and 83 ft·lbf (112 N·m).

Applications:

* Toyota Corolla E20 through E30 series
* Toyota Carina A40 series
* Toyota Celica A20 series
* Toyota Corona T70 series
* Daihatsu Charmant



12T-U

The 1588 cc 12T-U was produced from 1970 through 1983. It produces 88 hp (66 kW) at 5600 RPM and 96 ft·lbf (130 N·m) at 3400 RPM.

Applications:

* Toyota Corolla E30 series





2T-G(E/R/U)

The 2T-G, produced from 1970 through 1983, is a DOHC version. Output is 110-125 hp (82-93 kW) and 105-109 ft·lbf (142-147 N·m). Variants include the air-injected 2T-GR, Japan-spec 2T-GU, and fuel injected 2T-GEU. Twin sidedraft carburators were used in non-EFI versions.

Applications:

* Toyota Corolla Levin E20 through E70 series
* Toyota Celica A20 series



3T-(C/E/U) (1.8L)

The 3T displaces 1770 cc and was produced from 1977 through 1985. Cylinder bore is 85 mm (3.35 in) and stroke is 78 mm (3.07 in).

The 3T engines are usually coupled with either a T40 4 speed/T50 5 speed manual transmission, or an A40 4 speed automatic transmission. The exception is the 3T-GTE which is coupled with a W55 5 speed transmission.

Output ranges from 70-105 hp (52-78 kW) and 93-120 ft·lbf (126-162 N·m) between the California 3T-C and Japan-spec fuel injected 3T-EU.

Applications:

* Toyota Corolla E70 series
* Toyota Celica A40 series



13T-U

The 1770 cc 13T-U was produced from 1977 through 1982. It produces 95 hp (71 kW) at 5400 RPM and 109 ft·lbf (147 N·m) at 3400 RPM.

Applications:

* Toyota Corolla E70 series




3T-GTE

The production homologation model of the WRC-winning 4T-GTE is this engine, the 3T-GTE. It features a twin-spark (two spark plugs per cylinder) design and is turbocharged with a Toyota CT-20 Turbo to generate 160 hp (119 kW) at 6000 RPM and 152 ft·lbf (206 N·m) at 4800 RPM.

Applications:

* Toyota Celica A40 series



4T-GTE (2.1L)

This is the race-only version of the T family which powered Toyota's Group B and World Rally Championship cars. As the name implies, it is a 2090cc high-performance DOHC KKK turbo motor with fuel injection and uses a twin-spark design, which produces 370 to 600 hp depending on race trim.

Applications:

* Toyota Celica WRC Group B Rally Car

Camshaft

The camshaft is an apparatus often used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve. The cams force the valves open by pressing on the valve, or on some intermediate mechanism, as they rotate.



Timing

The relationship between the rotation of the camshaft and the rotation of the crankshaft is of critical importance. Since the valves control the flow of fuel intake and exhaust, they must be opened and closed at the appropriate time during the stroke of the piston. For this reason, the camshaft is connected to the crankshaft either directly, via a gear mechanism, or indirectly via a belt or chain called a timing belt or timing chain. In some designs the camshaft also drives the distributor and the oil and fuel pumps. Also on early fuel injection systems, cams on the camshaft would operate the fuel injectors.

In a two-stroke engine that uses a camshaft, each valve is opened once for each rotation of the crankshaft; in these engines, the camshaft rotates at the same rate as the crankshaft. In a four-stroke engine, the valves are opened only half as often; thus, two full rotations of the crankshaft occur for each rotation of the camshaft.



Duration

Duration can often be confusing because manufacturers may select any lift point to advertise a camshaft's duration and sometimes will manipulate these numbers. The power and idle charateristics of a camshaft rated at .006" will be much different than one rated the same at .002". Whenever duration is quoted, be sure to note the lift at which it is given.

Many performance engine builders have learned to gauge a race profile's aggressiveness by looking at the duration at .020", .050" and .200". The .020" number determines how responsive the motor will be and how much low end torque the motor will make. The .050" number is used to estimate where peak power will occur, and the .200" number gives them an estimate of the power potential.

In general, duration determines how many crankshaft degrees a camshaft maintains more than a given tappet lift.



Camshaft position

Depending on the location of the camshaft, the cams operate the valves either directly or through a linkage of pushrods and rockers. Direct operation involves a simpler mechanism and leads to fewer failures, but requires the camshaft to be positioned at the top of the cylinders. In the past when engines were not as reliable as today this was seen as too much bother, but in modern gasoline engines the overhead cam system, where the camshaft is on top of the cylinder head, is quite common. Some engines use one camshaft each for the intake and exhaust valves; such an arrangement is known as a double or dual overhead cam (DOHC), thus, a V engine may have four camshafts.



Maintenance

The rockers or cam followers sometimes incorporate a mechanism to adjust and set the valve play through manual adjustment, but most modern auto engines have hydraulic lifters, eliminating the need to adjust the valve lash at regular intervals as the valvetrain wears.

Sliding friction between the surface of the cam and the cam follower which rides upon it is considerable. In order to reduce wear at this point, the cam and follower are both surface hardened, and modern lubricant motor oils contain additives specifically to reduce sliding friction. The lobes of the camshaft are usually slightly tapered, causing the cam followers or valve lifters to rotate slightly with each depression, and helping to distribute wear on the parts. The surfaces of the cam and follower are designed to "wear in" together, and therefore when either is replaced, the other should be as well to prevent excessive rapid wear. In some engines, the flat contact surfaces are replaced with rollers, which eliminate the sliding friction and wear but adds mass to the valvetrain.



Alternatives

In addition to mechanical friction, considerable force is required to overcome the valve springs used to close the engine's valves. This can amount to an estimated 25% of an engine's total output at idle, reducing overall efficiency. Two approaches have been tried to reclaim this "wasted" energy but have proven difficult to implement:


* Springless valves, like the desmodromic system employed today by Ducati

* Camless valvetrains using solenoids or magnetic systems have long been investigated by BMW, and are currently being prototyped by Valeo and Ricardo

VVT-i

VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing technology developed by Toyota. The Toyota VVT-i system replaces the Toyota VVT offered starting in 1991 on the 4A-GE 20-Valve engine. The VVT system is a 2-stage hydraulically controlled cam phasing system.

VVT-i, introduced in 1996, varies the timing of the intake valves by adjusting the relationship between the camshaft drive (belt, scissor-gear or chain) and intake camshaft. Engine oil pressure is applied to an actuator to adjust the camshaft position. In 1998, "Dual" VVT-i (adjusts both intake and exhaust camshafts) was first introduced in the RS200 Altezza's 3S-GE engine. Dual VVT-i is also found in Toyota's new generation V6 engine, the 3.5L 2GR-FE V6. This engine can be found in the Avalon, RAV4, and Camry in the US, the Aurion in Australia, and various models in Japan, including the Estima. Other Dual VVT-i engines include the upcoming 1.8L 2ZR-FE I4, which will see implementation in Toyota's next generation of compact vehicles. By adjusting the valve timing, engine start and stop occur virtually unnoticeable at minimum compression, and fast heating of the catalytic converter to its light-off temperature is possible, thereby reducing HC emissions considerably.

Video animation of VVT-i (courtesy of PT. Toyota Astra Motor, Indonesia) can be found on the link below.


VVTL-i

In 1998, Toyota started offering a new technology, VVTL-i, which can alter valve lift (and duration) as well as valve timing. In the case of the 16 valve 2ZZ-GE, the engine has 2 camshafts, one operating intake valves and one operating exhaust valves. Each camshaft has two lobes per cylinder, one low rpm lobe and one high rpm, high lift, long duration lobe. Each cylinder has two intake valves and two exhaust valves. Each set of two valves are controlled by one rocker arm, which is operated by the camshaft. Each rocker arm has a slipper follower mounted to the rocker arm with a spring, allowing the slipper follower to move up and down with the high lobe with out affecting the rocker arm. When the engine is operating below 6000 rpm, the low lobe is operating the rocker arm and thus the valves. When the engine is operating above 6000 rpm, the ECU activates an oil pressure switch which pushes a sliding pin under the slipper follower on each rocker arm. This in effect, switches to the high lobe causing high lift and longer duration.

Toyota has now ceased production of its VVTL-i engines for most markets, because the engine does not meet Euro IV specifications for emissions. As a result, some Toyota models have been discontinued, including the Corolla T-Sport (Europe), Corolla Sportivo (Australia), Celica, Corolla XRS, Toyota Matrix XRS, and the Pontiac Vibe GT, all of which had the 2ZZ-GE engine fitted.

VTEC

VTEC (standing for Variable valve Timing and Electronic lift Control) is a system developed by Honda to improve the combustion efficiency of its internal combustion engines throughout the RPM range. This was the first system of its kind and eventually led to different types of variable valve timing and lift control systems that were later designed by other manufacturers (VVTL-i from Toyota, VarioCam Plus from Porsche, and so on). It was invented by Honda's chief engine designer Kenichi Nagahiro.



Introduction to VTEC


In the regular four-stroke automobile engine, the intake and exhaust valves are actuated by lobes on a camshaft. The shape of the lobes determines the timing, lift and duration of each valve. Timing refers to when a valve is opened or closed with respect to the combustion cycle. Lift refers to how much the valve is opened. Duration refers to how long the valve is kept open. Due to the behavior of the gases (air and fuel mixture) before and after combustion, which have physical limitations on their flow, as well as their interaction with the ignition spark, the optimal valve timing, lift and duration settings under low RPM engine operations are very different from those under high RPM. Optimal low RPM valve timing, lift and duration settings would result in insufficient fuel and air at high RPM, thus greatly limiting engine power output. Conversely, optimal high RPM valve timing, lift and duration settings would result in very rough low RPM operation and difficult idling. The ideal engine would have fully variable valve timing, lift and duration, in which the valves would always open at exactly the right point, lift high enough and stay open just the right amount of time for the engine speed in use.

VTEC can be used not only for economy but also for performance.

In practice, a fully variable valve timing engine is difficult to design and implement. Attempts have been made, using solenoids to control valves instead of the typical springs-and-cams setup, however these designs have not made it into production automobiles as they are very complicated and costly.

The opposite approach to variable timing is to produce a camshaft which is better suited to high RPM operation. This approach means that the vehicle will run very poorly at low RPM (where most automobiles spend much of their time) and much better at high RPM. VTEC is the result of an effort to marry high RPM performance with low RPM stability.

Additionally, Japan has a tax on engine displacement, requiring Japanese auto manufacturers to make higher-performing engines with lower displacement. In cars such as the Toyota Supra and Nissan 300ZX, this was accomplished with a turbocharger. In the case of the Mazda RX-7 (turbo) and RX-8, a wankel rotary engine was used. VTEC serves as yet another method to derive very high specific output from lower displacement motors.


DOHC VTEC

Honda's VTEC system is a simple method of endowing the engine with multiple camshaft profiles optimized for low and high RPM operations. Instead of one cam lobe actuating each valve, there are two - one optimized for low RPM stability & fuel efficiency, with the other designed to maximize high RPM power output. Switching between the two cam lobes is determined by engine oil pressure, engine temperature, vehicle speed, and engine speed. As engine RPM increases, a locking pin is pushed by oil pressure to bind the high RPM cam follower for operation. From this point on, the valve opens and closes according to the high-speed profile, which opens the valve further and for a longer time. The DOHC VTEC system has high and low RPM cam lobe profiles on both the intake and exhaust valve camshafts.

The VTEC system was originally introduced as a DOHC system in the 1989 Honda Integra sold in Japan, which used a 160 hp (119 kW) variant of the B16A engine. The US market saw the first VTEC system with the introduction of the 1991 Acura NSX, which used a DOHC VTEC V6. DOHC VTEC engines soon appeared in other vehicles, such as the 1992 Acura Integra GS-R.


SOHC VTEC

As popularity and marketing value of the VTEC system grew, Honda applied the system to SOHC engines, which shares a common camshaft for both intake and exhaust valves. The trade-off is that SOHC engines only benefit from the VTEC mechanism on the intake valves. This is because in the SOHC engine, the spark plugs need to be inserted at an angle to clear the camshaft, and in the SOHC engine, the spark plug tubes are situated between the two exhaust valves, making VTEC on the exhaust impossible.


SOHC VTEC-E

Honda's next version of VTEC, VTEC-E, was used in a slightly different way; instead of optimising performance at high RPM, it was used to increase efficiency at low RPM. At low RPM, one of the two intake valves is only allowed to open a very small amount, increasing the fuel/air atomization in the cylinder and thus allowing a leaner mixture to be used. As the engine's speed increases, both valves are needed to supply sufficient mixture. A sliding pin, which is pressured by oil, as in the regular VTEC, is used to connect both valves together and allows the full opening of the second valve.


3-Stage VTEC

Honda also introduced a 3-stage VTEC system in select markets, which combines the features of both SOHC VTEC and SOHC VTEC-E. At low speeds, only one intake valve is used. At medium speeds, two are used. At high speeds, the engine switches to a high-speed cam profile as in regular VTEC. Thus, both low-speed economy and high-speed efficiency and power are improved.


i-VTEC

i-VTEC (The i stands for intelligent) introduced continuously variable camshaft phasing on the intake cam of DOHC VTEC engines. The technology first appeared on Honda's K-series four cylinder engine family in 2001 (2002 in the U.S.). Valve lift and duration are still limited to distinct low and high rpm profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. Phase changes are implemented by a computer controlled, oil driven adjustable cam gear. Phasing is determined by a combination of engine load and rpm, ranging from fully retarded at idle to maximum advance at full throttle and low rpm. The effect is further optimization of torque output, especially at low and midrange RPM.

For the K-Series motors there are two different types of i-VTEC systems implemented. The first is for the performance motors like in the RSX Type S or the TSX and the other is for economy motors found in the CR-V or Accord. The performance i-VTEC system is basically the same as the DOHC VTEC system of the B16A's, both intake and exhaust have 3 cam lobes per cylinder. However the valvetrain has the added benefit of roller rockers and continuously variable intake cam timing. The economy i-VTEC is more like the SOHC VTEC-E in that the intake cam has only two lobes, one very small and one larger, as well as no VTEC on the exhaust cam. The two types of motor are easily distiguishable by the factory rated power output: the performance motors make around 200 hp or more in stock form and the economy motors do not make much more than 160 hp from the factory.

In 2004, Honda introduced an i-VTEC V6 (an update of the venerable J-series), but in this case, i-VTEC had nothing to do with cam phasing. Instead, i-VTEC referred to Honda's cylinder deactivation technology which closes the valves on one bank of (3) cylinders during light load and low speed (below 80 mph) operation. The technology was originally introduced to the US on the Honda Odyssey Mini Van, and can now be found on the Honda Accord Hybrid and the 2006 Honda Pilot. An additional version of i-VTEC was introduced on the 2006 Honda Civic's R-series four cylinder engine. This implementation uses very small valve lifts at low rpm and light loads, in combination with large throttle openings (modulated by a drive-by-wire throttle system), to improve fuel economy by reducing pumping losses.

With the continued introduction of vastly different i-VTEC systems, one may assume that the term is now a catch-all for creative valve control technologies from Honda.


Turbocharged VTEC

For 2007 models, Honda's Acura luxury division announced the RDX crossover SUV which will feature a new turbocharged 2.3 litre inline 4 cylinder i-VTEC engine. Honda has used turbochargers before (previous examples include the Honda City Turbo and City Turbo II).


Advanced VTEC

A September 25, 2006 press release announced the launch of the Advanced VTEC engine by Honda. The new engine combines continuously variable valve lift and timing control with the continuously variable phase control of VTC (Variable Timing Control). This new system permits optimum control over intake valve lift and phase in response to driving conditions, achieving improved charging efficiency for a significant increase in torque at all engine speeds. Under low to medium load levels, the valves are set for low lift and early closure to reduce pumping losses and improve fuel economy. In comparison to the 2.4L i-VTEC these advancements claim to increase fuel efficiency by 13%. Honda also claims that new engine also meets exhaust emission standards compliant with U.S. EPA - LEV2-ULEV regulations and Japanese Ministry of Land, Infrastructure and Transport requirements for Low-Emission Vehicles, with emission levels 75% lower than those required by the 2005 standards. The Advanced VTEC goes into production models in 3 years.


VTEC in motorcycles

Apart from the Japanese market-only Honda CB400 Super Four Hyper VTEC, introduced in 1999, the first worldwide implementation of VTEC technology in a motorcycle occurred with the introduction of Honda's VFR800 sportbike in 2002. Similar to the SOHC VTEC-E style, one intake valve remains closed until a threshold of 7000 rpm is reached, then the second valve is opened by an oil-pressure actuated pin. The dwell of the valves remains unchanged, as in the automobile VTEC-E, and little extra power is produced but with a smoothing-out of the torque curve. Critics maintain that VTEC adds little to the VFR experience while increasing the engine's complexity. Drivability is a concern for some who are wary of the fact that the VTEC may activate in the middle of an aggressive corner, potentially upsetting the stability and throttle response of the bike.

Honda B20A engine

Partially unrelated to the Honda B-series engines are the B20A and B21A. By some, these are not considered to be part of the B-series group of engines because they are not compatible with any of the other B-series parts or chassis.


There were 2 versions of the B20A

* The first generation of B20A engines was available in the 86-87 Prelude 2.0SI in Japan, the 86-89 Honda Vigor and Accord . It leaned towards the front of the car just like the A20A engine found in the same cars. This B20A produces 160 hp and 140 ft·lbf torque.

*
o There was also a similar engine named B18A for the 86-89 Accords. It was a destroked B20A powered by 2 Sidedraft Keihin carbs.

* The second generation of B20A was found in the 88-91 Prelude. The 88-91 Prelude B20A and B21A blocks are cast so they lay at an 18-degree angle leaning towards the firewall. This was done to please the exterior specifications for the 1988-1991 3rd Generation Prelude due to its ultra-low hoodline which Honda dubs the "engineless design".

The B20A, B20A3, and B20A5 engines consisted of closed-deck aluminum blocks with thicker-than-average iron sleeves where as the B21A1 had some special material.

The B21A1 was basically a re-worked B20A5 with an increase in bore to 83 mm. The external block dimensions had to stay identical to the B20A5 block so Honda called upon Saffil to create a thin but strong cylinder liner called FRM (Fiber Reinforced Metal) which basically consisted of a carbon fiber matrix, aluminum alloy, and aluminum oxide to make a very strong cylinder sleeve. These sleeves are so strong that they often do not lose their factory cross-hatching marks after 200,000 miles! A lot of B21A1 engines burn oil and have low cylinder compression numbers because the FRM material is so strong that it tears up piston rings. Good news though, you can usually replace the piston rings without any honing to the sleeves and go another 100,000+ miles without any sleeve wear.


B20A

(16-Valve, 4 Cylinder, DOHC, PGM-FI)

* Found in:
o Serial numbers 1000001~, 1500001~ and 1550001~ (Gold Valve Cover)
+ 1985-1986 Honda Prelude Non-U.S.
+ 1985-1986 Honda Accord Non-U.S.
+ 1985-1986 Honda Vigor Non-U.S.
o Serial numbers 1600001~ and 1640001~ (Black Valve Cover)
+ 1987-1989 Honda Accord Non-U.S.
+ 1987-1989 Honda Vigor Non-U.S.
* Displacement: 1958 cc
* Compression: 9.4:1
* Power: 160 hp @ 6300 rpm & 140 ft·lbf @ 5000 rpm
* Transmission: B2K5, F2K5


B20A

(16-Valve, 4 Cylinder, DOHC, PGM-FI)

* Found in:
o 1987-1990 Honda Prelude Japan Domestic Market
* This carries the same engine code as the original B20a above, but is actually a different engine.
* The serial number for these B20A will be: 5000001~


B20A2

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1986-1989 Honda Accord Non-U.S.


B20A3

(12-valve, SOHC, dual side-draft carburetors)

* Found in:
o 1988-1991 Honda Prelude 2.0 S
* HorsePower: 104 @ 5800 (MT) 105 @ 5800 (AT)
* Torque: 111 @ 4000


B20A4

(12-Valve, SOHC, dual side-draft carburetors)

* Found in:
o 1988-1991 Honda Prelude Non-U.S.


B20A5

(16-valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude 2.0Si
* Power: 135 hp
* Engine cc: 1958.14
* Cylinder cc: 489.535
* Deck cc: 13.885
* Head cc: 47.3
* Compression Ratio: 9.0:1

engine using a pk-2 honda ECU based on oki83c154 processor (intel 8051 based with external ROM)


B20A6

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. New Zealand, and Australian Domestic Market

140hp@6000rpm 170nm@5500rpm KY model is one of them



B20A7

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. UK, France, Holland, Norway, South Africa
* Power 150 hp@6000 rpm
o Torque 180Nm@5500 rpm
+ Compresion ratio 10.5:1


B20A8

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. Russian, Swedish Domestic Market


B20A9

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Non-U.S. Finland, German, Norway, Netherlands, Russia, Argentina
* Power 140 hp@6000 rpm
o Torque 175Nm@4500 rpm
+ Compresion ratio 10.5:1


B21A

(16-valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Si States
* Very rare, it was only produced for the "Si States" models in Japan
* Power: 185


B21A1

(16-valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Si
* Power: 140 hp @5800 rpm
* Torque: 135 lb.ft @5000 rpm
* Engine cc: 2056.03
* Cylinder cc: 514.0075
* Deck cc: 10.191
* Head cc: 51.0
* Compression Ratio: 9.4:1

Torque (lb.ft. @ rpm): 135@5000

Honda B20A engine

Partially unrelated to the Honda B-series engines are the B20A and B21A. By some, these are not considered to be part of the B-series group of engines because they are not compatible with any of the other B-series parts or chassis.


There were 2 versions of the B20A

* The first generation of B20A engines was available in the 86-87 Prelude 2.0SI in Japan, the 86-89 Honda Vigor and Accord . It leaned towards the front of the car just like the A20A engine found in the same cars. This B20A produces 160 hp and 140 ft·lbf torque.

*
o There was also a similar engine named B18A for the 86-89 Accords. It was a destroked B20A powered by 2 Sidedraft Keihin carbs.

* The second generation of B20A was found in the 88-91 Prelude. The 88-91 Prelude B20A and B21A blocks are cast so they lay at an 18-degree angle leaning towards the firewall. This was done to please the exterior specifications for the 1988-1991 3rd Generation Prelude due to its ultra-low hoodline which Honda dubs the "engineless design".

The B20A, B20A3, and B20A5 engines consisted of closed-deck aluminum blocks with thicker-than-average iron sleeves where as the B21A1 had some special material.

The B21A1 was basically a re-worked B20A5 with an increase in bore to 83 mm. The external block dimensions had to stay identical to the B20A5 block so Honda called upon Saffil to create a thin but strong cylinder liner called FRM (Fiber Reinforced Metal) which basically consisted of a carbon fiber matrix, aluminum alloy, and aluminum oxide to make a very strong cylinder sleeve. These sleeves are so strong that they often do not lose their factory cross-hatching marks after 200,000 miles! A lot of B21A1 engines burn oil and have low cylinder compression numbers because the FRM material is so strong that it tears up piston rings. Good news though, you can usually replace the piston rings without any honing to the sleeves and go another 100,000+ miles without any sleeve wear.


B20A

(16-Valve, 4 Cylinder, DOHC, PGM-FI)

* Found in:
o Serial numbers 1000001~, 1500001~ and 1550001~ (Gold Valve Cover)
+ 1985-1986 Honda Prelude Non-U.S.
+ 1985-1986 Honda Accord Non-U.S.
+ 1985-1986 Honda Vigor Non-U.S.
o Serial numbers 1600001~ and 1640001~ (Black Valve Cover)
+ 1987-1989 Honda Accord Non-U.S.
+ 1987-1989 Honda Vigor Non-U.S.
* Displacement: 1958 cc
* Compression: 9.4:1
* Power: 160 hp @ 6300 rpm & 140 ft·lbf @ 5000 rpm
* Transmission: B2K5, F2K5


B20A

(16-Valve, 4 Cylinder, DOHC, PGM-FI)

* Found in:
o 1987-1990 Honda Prelude Japan Domestic Market
* This carries the same engine code as the original B20a above, but is actually a different engine.
* The serial number for these B20A will be: 5000001~


B20A2

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1986-1989 Honda Accord Non-U.S.


B20A3

(12-valve, SOHC, dual side-draft carburetors)

* Found in:
o 1988-1991 Honda Prelude 2.0 S
* HorsePower: 104 @ 5800 (MT) 105 @ 5800 (AT)
* Torque: 111 @ 4000


B20A4

(12-Valve, SOHC, dual side-draft carburetors)

* Found in:
o 1988-1991 Honda Prelude Non-U.S.


B20A5

(16-valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude 2.0Si
* Power: 135 hp
* Engine cc: 1958.14
* Cylinder cc: 489.535
* Deck cc: 13.885
* Head cc: 47.3
* Compression Ratio: 9.0:1

engine using a pk-2 honda ECU based on oki83c154 processor (intel 8051 based with external ROM)


B20A6

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. New Zealand, and Australian Domestic Market

140hp@6000rpm 170nm@5500rpm KY model is one of them



B20A7

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. UK, France, Holland, Norway, South Africa
* Power 150 hp@6000 rpm
o Torque 180Nm@5500 rpm
+ Compresion ratio 10.5:1


B20A8

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1988-1991 Honda Prelude Non-U.S. Russian, Swedish Domestic Market


B20A9

(16-Valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Non-U.S. Finland, German, Norway, Netherlands, Russia, Argentina
* Power 140 hp@6000 rpm
o Torque 175Nm@4500 rpm
+ Compresion ratio 10.5:1


B21A

(16-valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Si States
* Very rare, it was only produced for the "Si States" models in Japan
* Power: 185


B21A1

(16-valve, DOHC, PGM-FI)

* Found in:
o 1990-1991 Honda Prelude Si
* Power: 140 hp @5800 rpm
* Torque: 135 lb.ft @5000 rpm
* Engine cc: 2056.03
* Cylinder cc: 514.0075
* Deck cc: 10.191
* Head cc: 51.0
* Compression Ratio: 9.4:1

Torque (lb.ft. @ rpm): 135@5000

Honda B engine

The B-series Honda DOHC engines are popular automotive engines from the modern series of Honda engines. They are good performers from the factory having models with around 126hp to around 200hp and even some models having a redline over 8,000 rpm. They accept high performance modifications well without much risk to reliability. The engine has been made in 1.6, 1.7, 1.8, and 2.0 liter variants, with and without VTEC (variable valve timing and electronic lift control). Later models have some minor upgrades, for instance modifications to the intake valves and ports and piston tops, and moving the dipstick away from the exhaust manifold.



Engine swaps

The B-series engine is one of the most common engines used for engine swaps in Hondas. Various versions are found in American junkyards, mostly in Acura Integras. They were also found in many JDM Hondas and are quite plentiful in Japanese junkyards, and great numbers have been imported from Japan in the last few years. The JDM engine has some slightly different parts (e.g. throttle body) than the USDM version, and tend to have slightly higher horsepower ratings with the JDM equivalent of the B18C1 producing 10 horsepower (7 kW) more than its USDM counterpart. Also, the wiring harness is set up for right hand drive as Japan uses, rather than left hand drive as in the United States or Canada; this is just a minor nuisance, however, as the wires will all fit if some of the mounting clips are released.

The B-series engine fits nicely under the hood of many Civics, a common target for such swaps. Note that the actual B-series engine will not adapt to the transaxle that came with other engine models, therefore the entire powertrain, i.e. engine and transaxle, must be swapped as a unit; normally, however, the entire powertrain is what is meant when "engine" swaps or availability of used "engines" is discussed with respect to front wheel drive cars.

Note that the ECU (engine computer) must be swapped as well. Aftermarket modified ECUs are available, ranging from close to stock B-series to wildly modified, with various degrees of skill. If a VTEC engine is to be installed in a car which did not have a VTEC engine, then additional wiring for the VTEC will have to be run; a minor chore.

The B-Series engine swap is very popular for 1992 through 1995 Civic owners since it is so easy to perform. The B-series engine was available in the United States 1994 Civic-based Del Sol; therefore the stock Honda motor mounts, axles, transmission linkage, and other auxiliary parts on the B-series engine (as well as the ECU, of course) will adapt it to any Civic of that era. Some swaps such as the B20B from the CRV are hard to perform due to the CRV's transmission not fitting therefore the need of a piecing together a transmission. The corresponding parts that came with the stock SOHC D-series engines will not fit the B-series, however. Unfortunately, most of the available engines are removed from the car without any of these parts, and often even the wiring harness has been destroyed, so the parts have to obtained by either scouring junkyards or purchased from Honda at substantial expense. If at all possible, an engine with a complete set of these parts is greatly to be desired over just the engine itself for this kind of swap.

If the engine is complete with these parts, very little else is needed for the 1992-1995 Civic, whether two door, four door, or hatchback. A bracket to adapt the existing throttle cable to the B-series engine is available from aftermarket manufacturers. As mentioned above, it may be necessary to add the VTEC wiring. If the B-series engine is older it may have a mechanical cable-operated clutch, and an aftermarket bracket will be needed to adapt it to the hydraulic clutch cylinder on the car. The only part which may need to be purchased from Honda is the bracket for the air conditioning compressor, if air conditioning is to be used; the stock bracket with most B-series motors will not fit, only the very specific bracket used for the B16 fitted in the Del Sol. [[VTEC is the key in all B-series motors]] For other generations, the swap is slightly harder because custom engine mounts must be used. Due to the popularity of the swaps, however, there are several manufacturers who make suitable mounts, such as Hasport.



Interchangeable Parts

B-series engine parts are largely interchangeable. This allows for custom engines to be built with characteristics unlike any factory model. Any B-Series VTEC cylinder head component will fit in any other B-Series VTEC cylinder head, so installing a Type-R (B16B or B18C5) camshaft into a GS-R motor will yield noticeable power gains. The higher-compression Integra Type-R pistons are a good choice for a bump in power, and also have an anti-friction coating and better oiling characteristics.

Also, complete Frankenstein motors (motors made from parts of others) are possible; these are also known as LS/VTEC. It is popular to take the large displacement, high-torque B18B (or B18A) bottom end and mate it to a high-flow B16 (PR3) or B18C (P72 or PR3) top end to make a very powerful custom motor. One problem however is the LS (B18A or B18B) and CR-V (B20B or B20Z) blocks used for LS/VTEC or CR-VTEC conversions are more prone to fail at high RPMs because the rod bolts and long stroke were not designed to withstand the high engine speeds that VTEC heads are optimized for. The LS/VTEC configuration is logically what Honda would have first considered when designing the B18C1, but they saw a reason to reduce the stroke, reinforce the bottom end, and add oil squirters to help cool it. The reduction in the stroke came at the cost of lowering the displacement from 1834 cc to 1797 cc, but helped enable the benefit of reliable 8100 RPM operation.


B16


B16A

Note: All JDM B16a engines are marked as 'B16a' (with no number to identify version).

* VTEC
* Found in:
o 1989-1993 JDM Honda Integra RSi/XSi (DA6/DA8)
o 1989-1991 JDM Honda CRX SiR (EF8)
o 1989-1991 JDM Honda Civic SiR/SiRII (EF9)
+ Displacement: 1595 cm³
+ Compression: 10.2:1
+ Rod/stroke ratio: 1.74
+ Power: 158 hp @ 7600 rpm & 112 ft·lbf @ 7000 rpm
+ Transmission: S1/J1/Y1/A1
o 1992-1995 JDM Honda Civic SiR/SiRII (EG6/EG9)
+ Displacement: 1595 cm³
+ Compression: 10.4:1
+ Power: 168 hp @ 7800 rpm & 116 ft·lbf @ 7300 rpm
+ Transmission: S4C
o 1992-1995 EDM Honda Civic VTi
+ Displacement: 1595 cm³
+ Power: 158 hp @ 7800 rpm & 116 ft·lbf @ 7300 rpm
o 1992-1996 JDM Honda CR-X del Sol SiR
+ Displacement: 1595 cm³
+ Compression: 10.2:1 / 10.4:1
+ Power: 158 hp - 170 hp & 111 ft·lbf - 116 ft·lbf


B16A1

* VTEC
* Found in:
o 1989-1991 EUDM Honda CRX 1.6i/VTi (EE8/ED)
o 1990-1991 EUDM Honda Civic 1.6iVT (EE9)
+ Displacement: 1595 cm³
+ Compression: 10.2:1
+ Power: 160 hp (117 kW) @ 7600 rpm & 111 ft·lbf (151 N·m) @ 7000 rpm


B16A2

* VTEC
o 1992-2000 Honda Civic EDM VTi (EG & EK)
+ Displacement: 1595 cm³
+ Compression: 10.2:1
+ Power: 158 hp @ 7600 rpm & 113 ft·lbf (153 N·m) @ 7300 rpm
+ Transmission: Y21
o 1999-2000 Honda Civic Si (EM1)
+ Displacement: 1595 cm³
+ Compression: 10.2:1
+ Power: 160 hp (118 kW) @ 7600 rpm & 111 ft·lbf (151 N·m) @ 7000 rpm
+ Transmission: Y21 S4C
o 1996-1997 Honda Del Sol VTEC (EG)
+ Displacement: 1595 cm³
+ Compression: 10.4:1
+ Power: 160 hp (119 kW) @ 7800 rpm & 111 ft·lbf (152 N·m) @ 7000 rpm
+ Transmission: Y21


B16A3

* VTEC
* Found in:
o 1994-1995 Honda Del Sol VTEC (EG)
+ Displacement: 1595 cm³
+ Compression: 10.4:1
+ Power: 160 hp (119 kW) @ 7800 rpm & 111 ft·lbf (152 N·m) @ 7000 rpm
+ Transmission: Y21


B16A6

* VTEC
* Found in:
o 1996-2000 Honda Civic - South Africa VTEC (EK)
+ Displacement: 1595 cm³
+ Compression: 10.2:1
+ Power: 160 hp (118 kW) @ 7800 rpm & 160 N·m @ 7400 rpm
+ Transmission: Y21


B16B

* VTEC
* Found in:
o 1997-2000 Civic Type-R
+ Displacement: 1595 cm³
+ Compression: 10.8:1
+ Power: 185 hp (137 kW) @ 8200 rpm & 118 ft·lbf (160 N·m) @ 7500 rpm
+ Transmission: S4C With LSD


B17


B17A1

* VTEC
* Found in:
o 1992-1993 Integra GS-R (DB2)
+ Displacement: 1678 cm³
+ Compression: 9.6:1
+ Power: 160 hp @ 7600 rpm & 117 ft·lbf (159 N·m) @ 7000 rpm
+ Transmission: Cable~ YS1


B18


B18A

* Non-VTEC
* Found in:
o 1986-1989 Accord Aerodeck LXR-S/LX-S (Japan)
o 1986-1989 Accord EXL-S/EX-S (Japan)
o 1986-1989 Vigor MXL-S (Japan)
+ Displacement: 1834 cm³
+ Compression: 9.4:1
+ Dual Keihin Carbs
+ Power: 130 hp (97 kW) @ 6000 rpm & 120 ft·lbf (164 N·m) @ 4000 rpm
+ Transmission: A2N5, E2N5

* This engine is not 100% related to the other B series engines. It is a destroked Honda B20A engine.


B18A1

Non-VTEC

* Found in:
o 1990-1993 Integra RS/LS/GS (DA)
+ Displacement: 1834 cm³
+ Compression: 9.2:1
+ Bore: 81 mm
+ Stroke: 89 mm
+ Power:
# 1990-1991: 130 hp (97 kW) @ 6000 rpm & 121 ft·lbf (164 N·m) @ 5000 rpm
# 1992-1994: 140 hp (104 kW) @ 6300 rpm & 127 ft·lbf (173 N·m) @ 5200 rpm
+ Transmission: YS1


B18B1

* Non-VTEC
* Found in:
o 1994-2001 Acura Integra "RS/LS/GS" (DC4/DB7)
+ Displacement: 1834 cc
+ Compression: 9.2:1
+ Bore: 81 mm
+ Stroke: 89 mm
+ Power:
# 142 hp (104 kW) @ 6300 rpm & 128 ft·lbf @ 5200 rpm
+ Transmission: S80

b18c10 costa rican model

* VTEC
* Found in:
o 1994 Honda Integra SiR-G
o 1995-1997 Honda Integra SiR
* Power: 180 hp (128 kW)
o 1995-2001 Honda Integra (DC2/DB8)(Japan) Type R
* Power: 200 hp @ 8100 rpm

acura integra 2006 300 horsepower stock


B18C1

* VTEC
* Found in:
o 1994-2001 Integra GS-R (DC2)
* Displacement: 1797 cm³
* Compression: 10.0:1
* Power: 170hp (127 kW) @ 7600 rpm & 128 ft·lbf (174 N·m) @ 6200 rpm
* Transmission: Y80


B18C3

* VTEC
* Found in:
o 1995-1998 Acura Integra Type R

Power: 185 hp


B18C4

* VTEC
* Found in:
o 1996-2000 UK Civic 1.8i VTi Acura
o 1998-1999 EU Civic Aerodeck 1.8i VTi 5-door Wagon
o 1998-1999 EU Civic 1.8i VTi 5-door Hatch
* Displacement: 1797 cm³
* Compression: 10.0:1
* Power: 169 hp (124 kW) @ 8000 rpm & 129 ft·lbf (174 N·m) @ 7500 rpm
* Transmission: S9B
* 0/100km/h : 8.5 seconds
* Top Speed : 215 km/h
* Limited Slip Diff


B18C5

* VTEC
* Found in:
o 1997-2001 Integra Type-R
* Displacement: 1797 cm³
* Compression: 11.0:1
* Power: 195 hp (145 kW) @ 8000 rpm & 130 ft·lbf (176 N·m) @ 7500 rpm
* Transmission: S80


B18C6

* VTEC
* Found in:
o 1998-2001 Honda Integra Type Rx
* Power: 200 hp (147 kW), 136 ft·lbf


B18C7

* VTEC
* Found in:
o 1996- Honda Integra Type R (Australia)
* Power: 210 hp (154 kW), 136 ft·lbf


B20

The B20A3 and B20A5 are not considered part of the B family. See Honda B20A engine.


B20B

* Found in: Honda CR-V, Honda Orthia
* Displacement: 1973
* Power: 126hp @ 5500rpm
* Torque: 133 ft @ 4200 rpm

* Compression: 8.8:1
* Bore: 84 mm[
* Stroke: 89 mm
* Redline: 6300 rpm red line


B20Z

* NON-VTEC
* Found in: 1999-2001 Honda CR-V
* Displacement: 1974
* Power: 146 hp @ 5500 rpm
* Torque: 133@ 4500 rpm
* Compression: 9.6:1
* Bore: 84 mm
* Stroke: 89 mm
* Redline: 6700 rpm


B20A/B21A

The B20A and B21A are not considered to be 100% part of the B family. See Honda B20A engine

Honda A engine

History

The Honda A-series engines succeeded the earlier EZ, ES, BS and ET engines in the Honda Accord and Prelude. Some of those engines were actually early A-series engines and parts between them may be cross-compatible. There were several variations, ranging from the 1.6 liter A16A to the 2.0 liter A20A. All A-series engines have iron blocks with single overhead camshaft aluminum heads and are the last iron blocked engine produced by Honda. They came in both carbed and fuel injected configurations.



Technology & Advancement

Although they don't have VTEC, the A-series engines were well-designed engines. Analysis of the head construction has showed that Honda was using valve geometry and technology several years ahead of their time. Also, the later model of the A20A3 & A20A4 benefitted from the addition of a dual-stage runner intake manifold design, 4-2-1 headers, and a more electronic form of the vacuum advanced distributor. The PGM-FI engines were equipped with partial OBD-0 engine computers.



Aftermarket

The aftermarket for the A-series engines (and the cars they came in) is all but dead. An A-equipped vehicle isn't for someone who wants bolt-ons from Wal-Mart or even your local import performance shop. Most upgrades and modifications to the A-series engines are of the DIY variety, with one of the more popular being a turbo set-up. Because of their closed-deck iron block design, they're especially well-suited for handling boost. It's just a pity that Honda didn't capitalize on that from the factory. And since a VTEC version of any of the A-series engines was never produced, swaps akin to an LS/VTEC or "mini-me" aren't doable because no VTEC head bolts to the A-series block.



A-Series Engines



A16A1

The A16A1 was a carburated 1.6 liter engine used in the 1982-1985 Honda Accords in North America and in some of the 1986-1989 Accords in the non-USDM market.

Specifications

* Carbeurated
* Displacement: 1596 cm³
* Bore: 80 mm
* Stroke: 79.5 mm
* Power:
o 88 hp @ 6000 rpm
o 91 ft/lb torque @ 3500 rpm



A18A

The A18A engine was the 1.8 liter engine found in the 1982-1985 Honda Accords as well as the 1984-1987 Honda Prelude in the US. Abroad, it was also available in the 1986-1989 Accords.

Specifications

* Carbeurated
* Displacement: 1829 cm³
* Bore:
* Stroke:
* Power:
o 110 hp @ 5800 rpm
o 112 ft/lbs @ 3500 rpm


A20A

The A20A is probably the most plentiful of all the Honda A-series engines. It was available in both carbeurated and PGM-FI versions. They were found in both Accords and Preludes throughout the 1980s.



A20A1 & A20A2

The A20A1 and A20A2 were the carbeurated versions of the A20A engines. It was available in the 1984-1987 Honda Preludes as well as the 1982-1989 Accord DX and LX. They are the same engine, the only difference between them being that the A20A2 has no emissions components, so it has a slightly higher power output (hp and tq numbers for A20A1 only).

Specifications

* Carbeurated
* Displacement: 1955 cm³
* Bore:
* Stroke:
* Power:
o 98 hp
o 109 ft/lb at 3500 rpm


A20A3 & A20A4

The A20A3 and A20A4 were the fuel injected versions of the A20A engines. They were run by Honda's PGM-FI system on a partial OBD-0 computer. Again, there is no real difference between the A20A3 and the A20A4 besides the A20A4 having a slightly higher power output because of not having emissions components (hp and tq numbers for A20A3 only). The A20A3 was offered in the 1984-1987 Honda Prelude 2.0Si, the 1985 and 1989 Honda Accord SE-i, and the 1986-1989 Honda Accord LX-i.

Specifications

* PGM-FI
* Displacement: 1956 cm³
* Bore:
* Stroke:
* Power:
o 1986-1987: 110 hp @ 5500 rpm & 114 ft/lb @ 4500 rpm
o 1988-1989: 120 hp @ 5500 rpm & 122 ft/lb @ 4000 rpm

Controlled Combustion Engine

Controlled Combustion Engine (CCE) is a type of internal combustion engine designed by Brad Howell-Smith in 1995. It uses two counter-rotating cams instead of a crankshaft driving two horizontally opposed pistons while retaining an identical cylinder head assembly to conventional engines.

It is around a quarter the size and weight of a conventional engine of similar output and uses fewer moving components. A four or two stroke cycle can be used and it can run on petrol, diesel, compressed natural gas or ethanol.

During the power stroke, maximum mechanical advantage is reached after the piston has moved approximately 5% of its travel from top dead centre (approx. 10° ATDC), which makes better use of the high cylinder pressures at this point in the cycle. In comparison a conventional engine reaches its maximum mechanical advantage after the piston has moved approximately 40% of its travel from top dead centre (approx. 60° ATDC). A side affect of this is a CCE can idle at a much lower RPM. In an independent analysis, torque output was shown to be 2.9 times greater than that of a conventional engine.

Because the piston assembly only moves in one dimension (unlike the case in an engine with connecting rods), contact with the cylinder wall is minimised, which reduces wear and lubrication requirements. The cams create less piston shock, which allows ceramic components to be used. The counter-rotating nature of the cams means that most rotational forces are cancelled, which eliminates the need for a heavy flywheel. The engine can run in either direction if symmetrical lobes are used.



Background

The idea came to Howell-Smith, an automotive engineer residing in Australia, during REM sleep. He designed five different engine layouts with variations on each and established Revolution Engine Technologies Pty Ltd in 1996 with a budget of A$2000. The first working prototype was built by father-in-law Peter Koch in Howell-Smith's garage. Howell-Smith founded a company named Revetec Limited and set up a research and development site in Sydney. The prototype was displayed at the 1996 Sydney International Motor Show which brought public awareness to the design. Work began on a second prototype intended for use in generators and pumps, however interest expressed by the Middle East automotive market shifted focus towards automotive applications. Revetec's business model is to license its technology to engine producers worldwide.

History Of Turbocharger

The turbocharger was invented by Swiss engineer Alfred Buchi, who had been working on steam turbines. His patent for the internal combustion turbocharger was applied for in 1905. Diesel ships and locomotives with turbochargers began appearing in the 1920s.

One of the first applications of a turbocharger to a non-Diesel engine came when General Electric engineer, Sanford Moss attached a turbo to a V12 Liberty aircraft engine. The engine was tested at Pikes Peak in Colorado at 14,000 feet to demonstrate that it could eliminate the power losses usually experienced in internal combustion engines as a result of altitude.

Turbochargers were first used in production aircraft engines in the 1930s prior to World War II. The primary purpose behind most aircraft-based applications was to increase the altitude at which the airplane can fly, by compensating for the lower atmospheric pressure present at high altitude. Aircraft such as the Lockheed P-38 Lightning, Boeing B-17 Flying Fortress and B-29 Superfortress all used exhaust driven "turbo-superchargers" to increase high altitude engine power. It is important to note that turbosupercharged aircraft engines actually utilized a gear-driven centrifugal type supercharger in series with a turbocharger.

Turbo-Diesel trucks were produced in Europe and America (notably by Cummins) after 1949. The turbocharger hit the automobile world in 1952 when Fred Agabashian qualified for pole position at the Indianapolis 500 and led for 100 miles before tire shards disabled the blower.

The first production turbocharged automobile engines came from General Motors. The A-body Oldsmobile Cutlass Jetfire and Chevrolet Corvair Monza Spyder were both fitted with turbochargers in 1962. The Oldsmobile is often recognized as the first, since it came out a few months earlier than the Corvair. Its Turbo Jetfire was a 215 in³ (3.5 L) V8, while the Corvair engine was either a 145 in³ (2.3 L)(1962-63) or a 164 in³ (2.7 L) (1964-66) flat-6. Both of these engines were abandoned within a few years, and GM's next turbo engine came more than ten years later.

Offenhauser's turbocharged engines returned to Indianapolis in 1966, with victories coming in 1968. The Offy turbo peaked at over 1,000 hp in 1973, while Porsche dominated the Can-Am series with a 1100 hp 917/30. Turbocharged cars dominated the Le Mans between 1976 and 1994.

BMW led the resurgence of the automobile turbo with the 1973 2002 Turbo, with Porsche following with the 911 Turbo, introduced at the 1974 Paris Motor Show. Buick was the first GM division to bring back the turbo, in the 1978 Buick Regal, followed by the Mercedes-Benz 300D and Saab 99 in 1978. The worlds first production turbodiesel automobile was also introduced in 1978 by Peugeot with the launch of the Peugeot 604 turbodiesel. Today, nearly all automotive diesels are turbocharged.

Alfa Romeo introduced first Italian (mass produced) turbocharged car Alfetta GTV 2000 Turbodelta in 1979, Pontiac also introduced a turbo in 1980 and Volvo Cars followed in 1981. Renault however gave another step and installed a turbocharger to the smallest and lightest car they had, the R5, making it the first Supermini automobile with a turbocharger in year 1980. This gave the car about 160bhp in street form and up to 300+ in race setup, an exorbitant power for a 1400cc motor. When combined with its incredible lightweight chassis, it could nip at the heels of the incredibly fast Ferrari 308.

In Formula One, in the so called "Turbo Era" of 1977 until 1989, engines with a capacity of 1500 cc could achieve anywhere from 1000 to 1500 hp (746 to 1119 kW) (Renault, Honda, BMW). Renault was the first manufacturer to apply turbo technology in the F1 field, in 1977. The project's high cost was compensated for by its performance, and led to other engine manufacturers following suit. The Turbo-charged engines took over the F1 field and ended the Ford Cosworth DFV era in the mid 1980s. However, the FIA decided that turbos were making the sport too dangerous and expensive, and from 1987 onwards, the maximum boost pressure was reduced before the technology was banned completely for 1989.

In Rallying, turbocharged engines of up to 2000cc have long been the preferred motive power for the Group A/World Rally Car (top level) competitors, due to the exceptional power-to-weight ratios (and enormous torque) attainable. This combines with the use of vehicles with relatively small bodyshells for manoeuvreability and handling. As turbo outputs rose to similar levels as the F1 category (see above), the FIA, rather than banning the technology, enforced a restricted turbo inlet diameter (currently 34mm), effectively "starving" the turbo of compressible air and making high boost pressures unfeasible. The success of small, turbocharged, four-wheel-drive vehicles in rally competition, beginning with the Audi Quattro, has led to exceptional road cars in the modern era such as the Subaru Impreza WRX and Mitsubishi Lancer Evolution.

Although late to use turbocharging, Chrysler Corporation turned to turbochargers in 1984 and quickly churned out more turbocharged engines than any other manufacturer, using turbocharged, fuel-injected 2.2 and 2.5 liter four-cylinder engines in minivans, sedans, and coupes. Their 2.2 liter turbocharged engines ranged from 142 hp to 225 hp, a substantial gain over the normally aspirated ratings of 86 to 93 horsepower; the 2.5 liter engines had about 150 horsepower and had no intercooler. Though the company stopped using turbocharges in 1993, they returned to turbocharged engines in 2002 with their 2.4 liter engines, boosting output by 70 horsepower.

Turbocharger

A turbocharger is an exhaust gas-driven compressor used to increase the power output of an internal-combustion engine by compressing air that is entering the engine thus increasing the amount of available oxygen. A key advantage of turbochargers is that they offer a considerable increase in engine power with only a slight increase in weight.



Principle of operation

A turbocharger is a dynamic compressor, in which air or gas is compressed by the mechanical action of impellers, vaned rotors which are spun using the kinetic movement of air, imparting velocity and pressure to the flowing medium.

The mechanical concept of a turbocharger revolves around three main parts. A turbine is driven by the exhaust gas from a pump, most often an internal combustion engine, to spin the second main part, an impeller whose function is to force more air into the pump's intake, or air supply. The third basic part is a center hub rotating assembly (CHRA) which contains bearing, lubrication, cooling, and a shaft that directly connects the turbine and impeller. The shaft, bearing, impeller, and turbine can rotate at speeds in the tens or hundreds of thousands of RPM (revolutions per minute).

The lubrication system can be either a closed system or be fed from the engine's oil supply. The lubrication system may double as the cooling system, or separate coolant may be pumped through the center housing from an outside source. An oil lubrication and water cooling system using engine oil and engine coolant are commonplace in automotive applications.
A Pair of turbochargers mounted to an Inline 6 engine in a dragster.
A Pair of turbochargers mounted to an Inline 6 engine in a dragster.

The turbine and impeller are each contained within their own folded conical housing on opposite sides of the center hub rotating assembly. These housings collect and direct the gas flow. The size and shape can dictate some performance characteristics of the overall turbocharger. The area of the cone to radius from center hub is expressed as a ratio (AR, A/R, or A:R). Often the same basic turbocharger assembly will be available from the manufacturer with multiple AR choices for the turbine housing and sometimes the compressor cover as well. This allows the designer of the engine system to tailor the compromises between performance, response, and efficiency to application or preference. Both housings resemble snail shells, and thus turbochargers are sometimes referred to in slang as snails.

By spinning at a relatively high speed the compressor turbine draws in a large volume of air and forces it into the engine. As the turbocharger's output flow volume exceeds the engine's volumetric flow, air pressure in the intake system begins to build, often called boost. The speed at which the assembly spins is proportional to the pressure of the compressed air and total mass of air flow being moved. Since a turbo can spin to RPMs far beyond what is needed, or of what it is safely capable of, the speed must be controlled. A wastegate is the most common mechanical speed control system, and is often further augmented by an electronic boost controller. The main function of a wastegate is to allow some of the exhaust to bypass the turbine when the set intake pressure is achieved.

The implementation of a turbocharger is to improve upon the size to output efficiency of an engine by solving for one of its cardinal limitations. A naturally aspirated automobile engine uses only the downward stroke of a piston to create an area of low pressure in order to draw air into the cylinder. Since the number of air and fuel molecules determine the potential energy available to force the piston down on the combustion stroke, and because of the relatively constant pressure of the atmosphere, there ultimately will be a limit to the amount of air and consequently fuel filling the combustion chamber. This ability to fill the cylinder with air is its volumetric efficiency. Since the turbocharger increases the pressure at the point where air is entering the cylinder, and the amount of air brought into the cylinder is largely a function of time and pressure, more air will be drawn in as the pressure increases. The intake pressure, in the absence of the turbocharger determined by the atmosphere, can be controllably increased with the turbocharger.

The application of a compressor to increase pressure at the point of cylinder air intake is often referred to as forced induction. Centrifugal superchargers operate in the same fashion as a turbo; however, the energy to spin the compressor is taken from the rotating output energy of the engine's crankshaft as opposed to exhaust gas. For this reason turbochargers are ideally more efficient, since their turbines are actually heat engines, converting some of the heat energy from the exhaust gas that would otherwise be wasted, into useful work. Superchargers use output energy to achieve a net gain, which is at the expense of some of the engine's total output.



Fuel efficiency

Since a turbocharger increases the specific horsepower output of an engine, the engine will also produce increased amounts of waste heat. This can sometimes be a problem when fitting a turbocharger to a car that was not designed to cope with high heat loads. This extra waste heat combined with the lower compression ratio (more specifically, expansion ratio) of turbocharged engines contributes to slightly lower thermal efficiency, which has a small but direct impact on overall fuel efficiency.

It is another form of cooling that has the largest impact on fuel efficiency: charge cooling. Even with the benefits of intercooling, the total compression in the combustion chamber is greater than that in a naturally-aspirated engine. To avoid knock while still extracting maximum power from the engine, it is common practice to introduce extra fuel into the charge for the sole purpose of cooling. While this seems counterintuitive, this fuel is not burned. Instead, it absorbs and carries away heat when it changes phase from liquid mist to gas vapor. Also, because it is more dense than the other inert substance in the combustion chamber, nitrogen, it has a higher specific heat and more heat capacitance. It "holds" this heat until it is released in the exhaust stream, preventing destructive knock. This thermodynamic property allows manufacturers to achieve good power output with common pump fuel at the expense of fuel economy and emissions. The optimum Air-to-Fuel ratio (A/F) for complete combustion of gasoline is 14.7:1. A common A/F in a turbocharged engine while under full design boost is approximately 12:1. Richer mixtures are sometimes run when the design of the system has flaws in it such as a catalytic converter which has limited endurance of high exhaust temperatures or the engine has a compression ratio that is too high for efficient operation with the fuel given.

Lastly, the efficiency of the turbocharger itself can have an impact on fuel efficiency. Using a small turbocharger will give quick response and low lag at low to mid RPMs, but can choke the engine on the exhaust side and generate huge amounts of pumping-related heat on the intake side as RPMs rise. A large turbocharger will be very efficient at high RPMs, but is not a realistic application for a street driven automobile. Variable vane and ball bearing technologies can make a turbo more efficient across a wider operating range, however, other problems have prevented this technology from appearing in more road cars (see Variable geometry turbocharger). Currently, the Porsche 911 (997) Turbo is the only gasoline car in production with this kind of turbocharger. One way to take advantage of the different operating regimes of the two types of supercharger is sequential turbocharging, which uses a small turbocharger at low RPMs and a larger one at high RPMs.

The engine management systems of most modern vehicles can control boost and fuel delivery according to charge temperature, fuel quality, and altitude, among other factors. Some systems are more sophisticated and aim to deliver fuel even more precisely based on combustion quality. For example, the Trionic-7 system from Saab Automobile provides immediate feedback on the combustion while it is occurring using an electrical charge.

The new 2.0L FSI turbo engine from Volkswagen/Audi incorporates lean burn and direct injection technology to conserve fuel under low load conditions. It is a very complex system that involves many moving parts and sensors in order to manage airflow characteristics inside the chamber itself, allowing it to use a stratified charge with excellent atomization. The direct injection also has a tremendous charge cooling effect enabling engines to use higher compression ratios and boost pressures than a typical port-injection turbo engine.



Design details

The ideal gas law states that when all other variables are held constant, if pressure is increased in a system so will temperature. Here exists one of the negative consequences of turbocharging, the increase in the temperature of air entering the engine due to compression.

A turbo spins very fast; most peak between 80,000 and 200,000 RPM (using low inertia turbos, 150,000-250,000 RPM) depending on size, weight of the rotating parts, boost pressure developed and compressor design. Such high rotation speeds would cause problems for standard ball bearings leading to failure so most turbo-chargers use fluid bearings. These feature a flowing layer of oil that suspends and cools the moving parts. The oil is usually taken from the engine-oil circuit. Some turbochargers use incredibly precise ball bearings that offer less friction than a fluid bearing but these are also suspended in fluid-dampened cavities. Lower friction means the turbo shaft can be made of lighter materials, reducing so-called turbo lag or boost lag. Some car makers use water cooled turbochargers for added bearing life.

Turbochargers with foil bearings are in development which eliminates the need for bearing cooling or oil delivery systems, thereby eliminating the most common cause of failure, while also significantly reducing turbo lag.

To manage the upper-deck air pressure, the turbocharger's exhaust gas flow is regulated with a wastegate that bypasses excess exhaust gas entering the turbocharger's turbine. This regulates the rotational speed of the turbine and the output of the compressor. The wastegate is opened and closed by the compressed air from turbo (the upper-deck pressure) and can be raised by using a solenoid to regulate the pressure fed to the wastegate membrane. This solenoid can be controlled by Automatic Performance Control, the engine's electronic control unit or an after market boost control computer. Another method of raising the boost pressure is through the use of check and bleed valves to keep the pressure at the membrane lower than the pressure within the system.

Some turbochargers (normally called variable geometry turbochargers) utilise a set of vanes in the exhaust housing to maintain a constant gas velocity across the turbine, the same kind of control as used on power plant turbines. These turbochargers have minimal amount of lag, have a low boost threshold (with full boost as low as 1,500 rpm), and are efficient at higher engine speeds; they are also used in diesel engines. [1] In many setups these turbos don't even need a wastegate. The vanes are controlled by a membrane identical to the one on a wastegate but the level of control required is a bit different.

The first production car to use these turbos was the limited-production 1989 Shelby CSX-VNT, in essence a Dodge Shadow equipped with a 2.2L petrol engine. The Shelby CSX-VNT utilised a turbo from Garrett, called the VNT-25 because it uses the same compressor and shaft as the more common Garrett T-25. This type of turbine is called a Variable Nozzle Turbine (VNT). Turbocharger manufacturer Aerocharger uses the term 'Variable Area Turbine Nozzle' (VATN) to describe this type of turbine nozzle. Other common terms include Variable Turbine Geometry (VTG), Variable Geometry Turbo (VGT) and Variable Vane Turbine (VVT). A number of other Chrysler Corporation vehicles used this turbocharger in 1990, including the Dodge Daytona and Dodge Shadow. These engines produced 174 horsepower and 225 pound-feet of torque, the same horsepower as the standard intercooled 2.2 liter engines but with 25 more pound-feet of torque and a faster onset (less turbo lag). However, the Turbo III engine, without a VATN or VNT, produced 224 horsepower. The reasons for Chrysler's not continuing to use variable geometry turbochargers are unknown, but the main reason was probably public desire for V6 engines coupled with increased availability of Chrysler-engineered V6 engines.

The 2006 Porsche 911 Turbo has a twin turbocharged 3.6-litre flat six, and the turbos used are BorgWarner's Variable Geometry Turbos (VGTs). This is significant because although VGTs have been used on advanced diesel engines for a few years and on the Shelby CSX-VNT, this is the first time the technology has been implemented on a production petrol car since the 1,250 Dodge engines were produced in 1989-90. Some have argued this is because in petrol cars exhaust temperatures are much higher (than in diesel cars), and this can have adverse effects on the delicate, moveable vanes of the turbocharger; these units are also more expensive than conventional turbochargers. Porsche engineers claim to have managed this problem with the new 911 Turbo.



Reliability

Turbochargers can be damaged by dirty or ineffective oil, and most manufacturers recommend more frequent oil changes for turbocharged engines; many owners and some companies recommend using synthetic oils, which tend to flow more readily when cold and do not break down as quickly as conventional oils. Because the turbocharger can get hot when running, many recommend letting the engine idle for one to three minutes before shutting the engine if the turbocharger was used shortly before stopping (most manufacturers specify a 10-second period of idling before switching off to ensure the turbocharger is running at its idle speed to prevent damage to the bearings when the oil supply is cut off). This lets the turbo rotating assembly cool from the lower exhaust gas temperatures, and ensures that oil is supplied to the turbocharger while the turbine housing and exhaust manifold are still very hot; otherwise coking of the lubricating oil trapped in the unit may occur when the heat soaks into the bearings, causing rapid bearing wear and failure when the car is restarted. Even small particles of burnt oil will accumulate and lead to choking the oil supply and failure. This problem is less pronounced in diesel engines, due to the lower exhaust temperatures and generally slower engine speeds.

A turbo timer can keep an engine running for a pre-specified period of time, to automatically provide this cool-down period. Oil coking is also eliminated by foil bearings. A more complex and problematic protective barrier against oil coking is the use of watercooled bearing cartridges. The water boils in the cartridge when the engine is shut off and forms a natural recirculation to drain away the heat. It is still a good idea to not shut the engine off while the turbo and manifold are still glowing.

In custom applications utilising tubular headers rather than cast iron manifolds, the need for a cooldown period is reduced because the lighter headers store much less heat than heavy cast iron manifolds.



Lag

A lag is sometimes felt by the driver of a turbocharged vehicle as a delay between pushing on the accelerator pedal and feeling the turbo kick-in. This is symptomatic of the time taken for the exhaust system driving the turbine to come to high pressure and for the turbine rotor to overcome its rotational inertia and reach the speed necessary to supply boost pressure. The directly-driven compressor in a positive-displacement supercharger does not suffer this problem. (Centrifugal superchargers do not build boost at low RPMs like a positive displacement supercharger will). Conversely on light loads or at low RPM a turbocharger supplies less boost and the engine is more efficient than a supercharged engine.

Lag can be reduced by lowering the rotational inertia of the turbine, for example by using lighter parts to allow the spool-up to happen more quickly. Ceramic turbines are a big help in this direction. Unfortunately, their relative fragility limits the maximum boost they can supply. Another way to reduce lag is to change the aspect ratio of the turbine by reducing the diameter and increasing the gas-flow path-length. Increasing the upper-deck air pressure and improving the wastegate response helps but there are cost increases and reliability disadvantages that car manufacturers are not happy about. Lag is also reduced by using a foil bearing rather than a conventional oil bearing. This reduces friction and contributes to faster acceleration of the turbo's rotating assembly. Variable-nozzle turbochargers (discussed above) also reduce lag.

Another common method of equalizing turbo lag is to have the turbine wheel "clipped", or to reduce the surface area of the turbine wheel's rotating blades. By clipping a minute portion off the tip of each blade of the turbine wheel, less restriction is imposed upon the escaping exhaust gases. This imparts less impedance onto the flow of exhaust gases at low RPM, allowing the vehicle to retain more of its low-end torque, but also pushes the effective boost RPM to a slightly higher level. The amount a turbine wheel is and can be clipped is highly application-specific. Turbine clipping is measured and specified in degrees.

Other setups, most notably in V-type engines, utilize two identically-sized but smaller turbos, each fed by a separate set of exhaust streams from the engine. The two smaller turbos produce the same (or more) aggregate amount of boost as a larger single turbo, but since they are smaller they reach their optimal RPM, and thus optimal boost delivery, faster. Such an arrangement of turbos is typically referred to as a parallel twin-turbo system.

Some car makers combat lag by using two small turbos (such as Kia, Toyota, Subaru, Maserati, Mazda, and Audi). A typical arrangement for this is to have one turbo active across the entire rev range of the engine and one coming on-line at higher RPM. Early designs would have one turbocharger active up to a certain RPM, after which both turbochargers are active. Below this RPM, both exhaust and air inlet of the secondary turbo are closed. Being individually smaller they do not suffer from excessive lag and having the second turbo operating at a higher RPM range allows it to get to full rotational speed before it is required. Such combinations are referred to as a sequential twin-turbo. Sequential twin-turbos are usually much more complicated than a single or parallel twin-turbo systems because they require what amounts to three sets of pipes-intake and wastegate pipes for the two turbochargers as well as valves to control the direction of the exhaust gases. An example of this is the current BMW E60 5-Series 535d. Another well-known example is the 1993-2002 Mazda RX-7. Many new diesel engines use this technology to not only eliminate lag but also to reduce fuel consumption and produce cleaner emissions.

Lag is not to be confused with the boost threshold; however, many publications still make this basic mistake. The boost threshold of a turbo system describes the minimum turbo RPM at which the turbo is physically able to supply the requested boost level [citation needed]. Newer turbocharger and engine developments have caused boost thresholds to steadily decline to where day-to-day use feels perfectly natural. Putting your foot down at 1200 engine RPM and having no boost until 2000 engine RPM is an example of boost threshold and not lag.

Electrical boosting ("E-boosting") is a new technology under development; it uses a high speed electrical motor to drive the turbocharger to speed before exhaust gases are available, e.g. from a stop-light. The electric motor is about an inch long.

Race cars often utilise an Anti-Lag System to completely eliminate lag at the cost of reduced turbocharger life.

On modern diesel engines, this problem is virtually eliminated by utilising a variable geometry turbocharger.



Boost

Boost refers to the increase in manifold pressure that is generated by the turbocharger in the intake path or specifically intake manifold that exceeds normal atmospheric pressure. This is also the level of boost as shown on a pressure gauge, usually in bar, psi or possibly kPa This is representative of the extra air pressure that is achieved over what would be achieved without the forced induction. Manifold pressure should not be confused with the amount, or "weight" of air that a turbo can flow.

Boost pressure is limited to keep the entire engine system including the turbo inside its design operating range by controlling the wastegate which shunts the exhaust gases away from the exhaust side turbine. In some cars the maximum boost depends on the fuel's octane rating and is electronically regulated using a knock sensor, see Automatic Performance Control (APC).

Many diesel engines do not have any wastegate because the amount of exhaust energy is controlled directly by the amount of fuel injected into the engine and slight variations in boost pressure do not make a difference for the engine.



Applications

Turbocharging is very common on diesel engines in conventional automobiles, in trucks, locomotives, for marine and heavy machinery applications. In fact, for current automotive applications, non-turbocharged diesel engines are becoming increasingly rare. Diesels are particularly suitable for turbocharging for several reasons:

* Naturally-aspirated diesels have lower power-to-weight ratios compared to gasoline engines; turbocharging will improve this P:W ratio.

* Diesel engines require more robust construction because they already run at very high compression ratio and at high temperatures so they generally require little additional reinforcement to be able to cope with the addition of the turbocharger. Gasoline engines often require extensive modification for turbocharging.

* Diesel engines have a narrower band of engine speeds at which they operate, thus making the operating characteristics of the turbocharger over that "rev range" less of a compromise than on a gasoline-powered engine.

* Diesel engines blow nothing but air into the cylinders during cylinder charging, squirting fuel into the cylinder only after the intake valve has closed and compression has begun. Gasoline/petrol engines differ from this in that both fuel and air are introduced during the intake cycle and both are compressed during the compression cycle. The higher intake charge temperatures of forced-induction engines reduces the amount of compression that is possible with a gasoline/petrol engine, whereas diesel engines are far less sensitive to this.

Today, turbocharging is most commonly used on two types of engines: Gasoline engines in high-performance automobiles and diesel engines in transportation and other industrial equipment. Small cars in particular benefit from this technology, as there is often little room to fit a larger-output (and physically larger) engine. Saab is a leader in production car turbochargers, starting with the 1978 Saab 99; all current Saab models are turbocharged. The Porsche 944 utilized a turbo unit in the 944 Turbo (Porsche internal model number 951), to great advantage, bringing its 0-100 km/h (0-60 mph) times very close to its contemporary non-turbo "big brother", the Porsche 928.

Chrysler Corporation was an innovator of turbocharger use in the 1980s. Many of their production vehicles, for example the Chrysler LeBaron, Dodge Daytona, Dodge Shadow/Plymouth Sundance twins, and the Dodge Spirit/Plymouth Acclaim twins were available with turbochargers, and they proved very popular with the public. They are still considered competitive vehicles today, and the experience Chrysler obtained in observing turbochargers in real-world conditions has allowed them to further turbocharger technology with the PT Cruiser Turbo, the Dodge SRT-4 and the Dodge Caliber SRT-4.

Small car turbos are increasingly being used as the basis for small jet engines used for flying model aircraft—though the conversion is a highly specialised job—one not without its dangers. Jet engine enthusiasts have constructed home-built jet engines from automotive turbochargers, often running on propane and using a home-built combustion canister plumbed in between the high pressure side of the turbo's compressor and the intake side of the turbine. An oil supply for the bearings is still needed, usually provided by an electric pump. Starting such home-built jets is usually achieved by blowing air through the unit with a compressor or a domestic leaf-blower. Making these engines is not an easy task- unless the combustion canister design is correct the engine will either fail to start, fail to stabilise once running or even over-rev and destroy itself.

Most modern turbocharged aircraft use an adjustable wastegate. The wastegate is controlled manually, or by a pneumatic/hydraulic control system, or, as is becoming more and more common, by a flight computer. In the interests of engine longevity, the wastegate is usually kept open, or nearly so, at sea-level to keep from overboosting the engine. As the aircraft climbs, the wastegate is gradually closed, maintaining the manifold pressure at or above sea-level. In aftermarket applications, aircraft turbochargers sometimes do not overboost the engine, but rather compress ambient air to sea-level pressure. For this reason, such aircraft are sometimes referred to as being turbo-normalised. Most applications produced by the major manufacturers (Beech, Cessna, Piper and others) increase the maximum engine intake air pressure by as much as 35%. Special attention to engine cooling and component strength is required because of the increased combustion heat and power.

Turbo-Alternator is a form of turbocharger that generates electricity instead of boosting engine's air flow. On September 21, 2005, Foresight Vehicle announced the first known implementation of such unit for automobiles, under the name TIGERS (Turbo-generator Integrated Gas Energy Recovery System).

Bourke engine

The Bourke engine was designed by Russell Bourke in the late 1930s, who endeavored to improve upon the Otto cycle engine. Despite finishing his redesign and building several working engines; bad luck (onset of World War II), bad health and a know-it-all attitude compounded to prevent his engine from ever coming to market despite its claimed advantages. Well into the 2000's there are several small groups extolling the virtues of the design. The Bourke engine has two opposed cylinders with the pistons in a Scotch yoke mechanism. Because the motion of the pistons is a perfect sine wave with regards to time vs displacement the fuel burns in a smaller volume, and so burns hotter. The Bourke engine also has a looser coupling with the output shaft, preventing excess vibration. The intake valves are replaced by ports, saving on parts.

It is thought that the design features that increase its efficiency, namely the detonation mode of combustion, may cause emission problems. The higher combustion temperatures combined with the increased cycle time around top dead center may lead to increased nitrogen oxide emissions. There have not been any verified nitrous oxide tests on running engines to verify the emission problem.


Design features

* Scotch yoke instead of connecting rods to translate motion to rotary motion
o Fewer (only 3) moving parts
o Smoother operation
o Longer percentage of cycle spent at top dead center and bottom-dead-center for more complete combustion and exhaust scavenging

* Two power strokes for every rotation from the opposed pistons instead of one every other rotation (4-stroke) resulting in nearly twice the power at a given engine speed

* Expanding gasses cause adiabatic cooling reaction as opposed to a drawn out combustion and heating reaction.

* Lean fuel/air mixture combined with the adiabatic cooling reaction resulting in zero unburnt hydrocarbons in the exhaust

* Sealed underside of the piston to isolate the fuel/air mixture from the crankcase

o Eliminate the need to mix oil with the fuel as with standard two-stroke engines
o Prevents the piston ring blow by from polluting the crankcase oil extending the life of the oil



Simplified explanation:

The Bourke engine should be considered a detonation or "explosion" engine because of the extremely fast burn time of the fuel air mixture.

The rising piston compresses the mixture heating it, because of the cool piston head and cylinder walls the mixture is not heated enough to start a burn. The piston "latches" at top dead center because of the action of the scotch yoke. Spark plug fires causing an explosive burn. All of fuel is burned completely because of explosive burn time. Sharp rise in pressure causes scotch yoke to "unlatch" piston. Piston moves down cylinder, expanding gases following piston cause cooling of piston and cylinder walls. Since all of fuel was burned during "latching" of piston no fuel is being burned at this time, no heat is being added, all expansion results in cooling. When piston reaches the bottom of the cylinder it again "latches" until "unlatched" by the explosion in the opposite cylinder. This gives time for scavenging of explosive gases and injection of fuel air mixture.

The mixture must be lean enough so that compression heating of the mixture does not cause it to ignite prior to the "latching". If this occurs engine will not run, or will run rough. Mixture of the fuel must be in the "explosive" range for the engine to run correctly. Any fuel that is used that is mixed into its "explosive" range will work on this engine thus giving it multi-fuel capabilities.

The maximum pressure on the piston occurs right after the release of the piston from top dead center. It is not spread over the whole length of the piston travel as in a conventional engine. For this reason this is an extremely high torque engine.

The complete burn of the fuel while the piston is "latched" gives this engine its high efficiency and low emissions.

The cooling caused by the expanding gases, behind the piston head and the non burning of fuel while piston is traveling, causes the low temperature exhaust gases. This also prevents dieseling during the next compression cycle, because of the cooling of the piston head.

Air enters under the piston head, where it is compressed (turbocharging). It then leaves from under the piston and is mixed with fuel, prior to being injected above the piston. This injection occurs at the same time, but at the other side of the cylinder port, that the exhaust gasses leave. Because of the shape of the piston the injected mixture hitting the sloped piston head cause a swirling action that leads to complete mixing of fuel/air. This mixing contributes to the complete explosive burn. The sloped piston head effectively separate the incoming mixture from the scavaging of the exhaust gases.

Piston is connected to the Scottish yoke through a "triple slipper bearing". This bearing absorbs and smooths out the force from the explosive burn preventing deformation/breaking of engine parts. The bearing also absorbs any lateral forces, preventing vibrations. This bearing is the "key" to the engine. Without this bearing the explosive forces would "tear the engine apart".

Compression ratio needs to be adjusted for type of fuel burnt. If compression ratio is to high speed control becomes erratic do to dieseling. Adjusting the compression ratio allows burning of both low and high octane fuels.

Piston shape, with higher volume around edges, contributes to complete explosive burn.

Gasket

A gasket is a mechanical seal that serves to fill the space between two objects, generally to prevent leakage between the two objects while under compression. Gaskets save money by allowing less precise mating surfaces on machine parts which can use a gasket to fill irregularities. Gaskets are commonly produced by cutting from sheet materials, such as gasket paper, rubber, silicone, metal, felt, fiberglass, or a plastic polymer. Gaskets for specific applications may contain asbestos. It is usually desirable that the gasket be made from a material that is to some degree compressible such that it tightly fills the space it is designed for, including any slight irregularities.

One of the more desirable properties of an effective gasket in industrial applications for compressed fiber gasket material is the ability to withstand high compressive loads. Most industrial gasket applications involve bolts exerting compression well into the 14 MPa (2000 psi) range or higher. Generally speaking, there are several truisms that allow for best gasket performance. One of the more tried and tested is: "The more compressive load exerted on the gasket, the longer it will last". There are several ways to measure a gasket material's ability to withstand compressive loading. The "hot compression test" is probably the most accepted of these. Most manufacturers of gasket materials will provide or publish these results.



Gaskets:

1. o ring
2. fiber washer
3. paper gaskets
4. cylinder head gasket

Compression Ratio

The compression ratio is a single number that can be used to predict the performance of any engine (such as an internal-combustion engine or a Stirling Engine). It is a ratio between the volume of a combustion chamber and cylinder, when the piston is at the bottom of its stroke and the volume when the piston is at the top of its stroke. The higher the compression ratio, the more mechanical energy an engine can squeeze from its air-fuel mixture. Literally, high ratios place increased oxygen and fuel molecules into a reduced space, thus allowing for increased power at the moment of ignition. Higher compression ratios, however, also make detonation more likely.

The ratio is calculated by the following formula:




b = cylinder bore (diameter)

s = piston stroke length

Vc = volume of the combustion chamber (including head gasket). This is the minimum volume of the space into which the fuel and air is compressed, prior to ignition. Because of the complex shape of this space, it usually is measured directly rather than calculated.

* Due to pinging (detonation), the CR in a gasoline/petrol powered engine will usually not be much higher than 10:1, although some production automotive engines built for high-performance from 1955-1972 had compression ratios as high as 12.5:1, which could run safely on the high-octane leaded gasoline then available. Recently, with the addition of variable valve timing and knock sensors to delay ignition timing, one worldwide manufacturer is building 10.8 CR gasoline engines that use (U.S.) 87 octane fuel.

* In engines running exclusively on LPG or CNG, the CR may be higher, due to the higher octane rating of these fuels.

* IC racing engines burning methanol and ethanol often exceed a CR of 15:1.

* In engines with a 'ping' or 'knock' sensor and an electronic control unit, the CR can be as high as 13:1 (2005 BMW K1200S)

* In a turbocharged or supercharged engine, the CR is customarily built at 8.5:1 or lower.

* In an auto-ignition diesel engine, the CR will customarily exceed 14:1--and over 22:1 is not uncommon.



Fault finding and diagnosis

Measuring the compression pressure of an engine, with a pressure gauge connected to the spark plug opening, gives an indication of the engine's state and quality.

If the nominal compression ratio of an engine is given, e.g. as 10:1, the measured pressure in each cylinder of common automotive designs can be roughly estimated in pounds per square inch as between 15 and 20 times the compression ratio, or in this case between 150 psi and 200 psi, depending on cam timing. Purpose-built racing engines, stationary engines etc. will return figures outside this range.

If there is a significant (> 10%) difference between cylinders, that may be an indication that valves or cylinder head gaskets are leaking, piston rings are worn or that the block is cracked.

If a problem is suspected then a more comprehensive test using a leak-down tester can locate the leak.



Saab Variable Compression engine

Because cylinder bore diameter, piston stroke length and combustion chamber volume are almost always constant, the compression ratio for a given engine is almost always constant, until engine wear takes its toll.

One exception is the experimental Saab Variable Compression engine (SVC). This engine, designed by Saab Automobile, uses a technique that dynamically alters the volume of the combustion chamber (Vc), which, via the above equation, changes the compression ratio (CR).

To alter Vc, the SVC 'lowers' the cylinder head closer to the crankshaft. It does this by replacing the typical one-part engine block with a two-part block, with the crankshaft in the lower block and the cylinders in the upper portion. The two blocks are hinged together at one side (imagine a book, lying flat on a table, with the front cover held an inch or so above the title page). By pivoting the upper block around the hinge point, the Vc (imagine the air between the front cover of the book and the title page) can be modified. In practice, the SVC adjusts the upper block through a small range of motion, using a hydraulic actuator.

The SVC project was shelved by General Motors, when it took over Saab Automobile, due to cost.



Variable Compression Ratio (VCR) Engines

The SAAB SVC is a very late addition to the world of VCR engines, the first being built and tested by Harry Ricardo in the 1920s. This work led to him devising the octane rating system that is still in use today. The company has recently been involved in working with the 'Office of Advanced Automotive Technologies', to produce a modern petrol VCR engine that showed an efficiency comparable with that of a Diesel. Many companies have been carrying out their own research in to VCR Engines, including Nissan, Volvo, PSA/Peugeot-Citroën and Renault.

The Atkinson cycle engine was one of the first attempts at variable compression. Since the compression ratio is the ratio between dynamic and static volumes of the combustion chamber the Atkinson cycle's method of increasing the length of the powerstroke compared to the intake stroke ultimately altered the compression ratio at different stages of the cycle.



Dynamic Compression Ratio

The calculated compression ratio, as given above, presumes that the cylinder is sealed at the bottom of the stroke (BDC or bottom dead center), and that the volume compressed is the actual volume.

This is not true: intake valve closure (sealing the cylinder) always takes place after BDC, which causes some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds; only the percentage of the stroke after intake valve closure is compressed. This "corrected" compression ratio is commonly called the "dynamic compression ratio".

This ratio is higher with more conservative (i.e., earlier, soon after BDC) intake cam timing, and lower with more radical (i.e., later, long after BDC) intake cam timing, but always lower than the static or "nominal" compression ratio. The actual position of the piston can be determined by trigonometry, using the stroke length and the connecting rod length (measured between centers). The absolute cylinder pressure is the result of an exponent of the dynamic compression ratio. This exponent is a polytropic value for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. Under ideal (adiabatic) conditions, the exponent would be 1.4, but a lower value, generally between 1.2 and 1.3 is used, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison. For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be (7.5)^1.3 × atmospheric pressure, or 13.727 × 14.7 psi at sea level, or 201.8 psi. The pressure shown on a gauge would be the absolute pressure less atmospheric pressure, or 187.1 psi. From this, we can see that the two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength. An engine with high static compression ratio and late intake valve closure will have a DCR similar to an engine with lower compression but earlier intake valve closure.

Harley-Davidson motorcycle flathead engines

The flathead engine saw service Harley-Davidson motorcycles beginning with the "sport" model opposed twin produced from 1919-1923, and continuing in 1924 with single cylinder export 350cc and 500cc singles and continued in the Servicars until the 1970s. In the domestic U.S. market, the DL model, 1929-36, started Harley's side valve tradition in the 45 cubic inch displacement. The DLs featured a total loss oiling system (oil's always clean!), and were succeeded in 1937 by the WL, which had recirculating oil. The WL went on to serve in WWII as the U.S. and Canadian Army's primary two wheeled mount and subsequently as a civilian middleweight through 1952. The engine continued virtually unchanged with the GA designation in the three wheeled Servicar until production ceased in 1976.

In 1952, the W series was supplanted by the K series flatheads, designed to compete with British sporting motorcycles of the time. The K models featured unit construction engine and transmission cases, right side foot shift and left side foot brake, and evolved from 45 cubic inches to 55 cubic inches over the short life of the retail market run. The K series was replaced by the overhead valve Sportster series in the retail market in 1957. However, racing versions of the K model continued to be produced in very limited numbers for some time after, winning both roadraces and dirt track through 1969, when the American Motorcycle Association decided to change the rules and make the venerable flatheads uncompetitive. The K racers were replaced first by the iron XR 750cc overhead valve engine, and two years later by the alloy head XR, which continues in service in flat track racing to this day.

In 1930, the 74 cubic inch VL flathead replaced the JD, which featured intake over exhaust (IoE) valve configuration. The VL had a single downtube frame and total loss oiling, culminating in an 80 cubic inch version in 1936. In 1937, the engine was given the U designation and went into the same frame and running gear configuration as the overhead valve Knucklehead, which originated in 1936. The U continued to be produced, in varying configurations as both a 74 cubic inch and 80 cubic inch motor through 1948. By that time, the first year of the Panhead, it had been thoroughly superseded and outsold in the marketplace by the superior performance of the overhead valve model big twins.


Harley-Davidson engine timeline

Flathead: 1929–1936 *Big twins until 1948 commercial market as models UL and ULH, WL 45 cubic inch until 1952-some literature indicating existence up to 1952 engine serial numbers displayed at motorcycle shows, old dealer catalog showed as optional engine until 1952 for limited market- sidecar use or military/ government contract completion . K models 1956 - was model prior to OHV CH /sportster. KRs made/raced even later. Servicar/'trike' noted preceding sentence to 1970s. RN*

Knucklehead: 1936–1947

Panhead: 1948–1965

Shovelhead: 1966–1985

Evolution: 1984–1999

Twin Cam 88: 1999—

Revolution: 2002—

Flathead engine

Flathead engine or Sidevalve engine(sometimes called a flatty) refers to an internal combustion engine with valves placed in the engine block beside the piston, instead of in the cylinder head, as in an overhead valve engine. The design was common on early engine designs, but has since fallen from use.

Generally the flathead uses a small chamber on one side of the cylinder to carry the valves. This has a number of advantages, primarily making the cylinder head much simpler. It also means a valve can be operated by pushing directly up on it, as opposed to needing some sort of mechanical arrangement to push it down or to drive overhead cams, as on a "valve-in-head" engine. It may also lead to slightly easier cooling, as valve and pushrods are out of the way of the cylinder, making a cooling jacket simpler to construct (but see below). The line of intakes along the side of the engine leads to the alternate name L-block (or L-head), due to the cylinders having the shape of an upside-down L. This configuration is also known as sidevalve.

On the downside, the flathead also requires the airflow to make at least a 90-degree turn to enter the cylinder, which makes it less efficient, colloquially called poorer "breathing". Breathing was not greatly important for early production cars because engines could not run long and reliably at high speed, and all engines had poor combustion anyway, so this was a minor concern given the benefits in simplicity.

A more serious concern is exhaust, which often follows a more complicated path to leave the engine. This virtually guarantees the engine will overheat under sustained steady heavy use. It is sometimes possible to arrange the engine layout so the exhaust will be taken through a second set of similar chambers moved to the other side of the cylinder, in which case the layout is referred to as a T-block.

Although flathead in-line 4 and 6 cylinder engines were frequently used for automobiles, tractors, etc., the best known flathead automotive engine is the early 20th century Ford V-8, which has both sets of valves (intake and exhaust) located on the inside of the "Vee," and which are all operated by a single camshaft located above the crankshaft.

Due to the heating and efficiency problems, flathead engines fell from "high power" uses such as aircraft engines fairly quickly, prior to World War I, though they were the basis of many early racing engines, including famous names such as Ardun (Zora Duntov) and Frontenac (Louis Chevrolet). However they lived on for some time in the automotive world and were used on the Jeep for instance. Flatheads are no longer in common use for automobiles, although they are still used for some small-engine applications like lawnmowers. Because of their design, the size of valves and the compression ratio are limited, which in turn reduces available power and economy.

Cylinder head

In an internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the combustion chamber and the location of the valves and spark plugs. In a flathead engine, the mechanical parts of the valve train are all contained within the block, and the head is essentially a flat plate of metal bolted to the top of the cylinder bank; this simplicity leads to ease of manufacture and repair, and accounts for the flathead engine's early success in production automobiles and continued success in small engines, such as lawnmowers. This design, however, requires the incoming air to flow through a convoluted path, which limits the ability of the engine to perform at higher rpm, leading to the adoption of the overhead valve head design.

In the overhead valve head, the top half of the cylinder head contains the camshaft in an overhead cam engine, or another mechanism (such as rocker arms and pushrods) to transfer rotational mechanics from the crankshaft to linear mechanics to operate the valves (pushrod engines perform this conversion at the camshaft lower in the engine and use a rod to push a rocker arm that acts on the valve). Internally the cylinder head has passages called ports for the fuel/air mixture to travel to the inlet valves from the intake manifold, for exhaust gases to travel from the exhaust valves to the exhaust manifold, and for antifreeze (coolant) to cool the head and engine.

The number of cylinder heads in an engine is a function of the engine configuration. A straight engine has only one cylinder head. A V engine usually has two cylinder heads, one at each end of the V, although Volkswagen, for instance, produces a V6 called the VR6, where the angle between the cylinder banks is so narrow that it utilizes a single head. A boxer engine has two heads.

The cylinder head is key to the performance of the internal combustion engine, as the shape of the combustion chamber, inlet passages and ports (and to a lesser extent the exhaust) determines a major portion of the volumetric efficiency and compression ratio of the engine.

Combustion chamber

Internal Combustion Engine

A combustion chamber is part of an engine in which fuel is burned. The leftover hot gases produced by this combustion tend to occupy a far greater volume than the original fuel, thus creating an increase in pressure within the limited volume of the chamber. This pressure can be used to do work, for example, to move a piston on a crankshaft. The energy can be converted to various types of motion or to produce thrust when directed out of a nozzle as in a rocket or jet engine.

In a reciprocating engine, the moving pistons are flush with the top of the cylinder block at top dead centre, and the combustion chamber is therefore the recess in the cylinder head which contains the valves. Some engines use a dished piston and in this case the combustion chamber can be considered as partly within the cylinder. Various shapes of combustion chamber have been used, such as L-head (or flathead) for side-valve engines, "bathtub","hemispherical" and "wedge" for overhead valve engines and "pent-roof" for engines having 3, 4 or 5 valves per cylinder. The shape of the chamber has a marked effect on power output, efficiency and harmful emissions; the designer's objectives are to burn all of the mixture as completely as possible while avoiding excessive temperatures (which create NOx). This is best achieved with a compact rather than elongated chamber. The intake valve/port is usually placed to give the mixture a pronounced "swirl" (the term is preferred to "turbulence" which implies uncontrolled movement) above the rising piston, improving mixing and combustion. Finally, the spark plug must be situated in a position from which the flame front can reach all parts of the chamber at the desired point, usually around 15 degrees after top dead centre. It is strongly desirable to avoid narrow crevices where stagnant "end gas" can become trapped, as this tends to detonate violently after the main charge, adding little useful work and potentially damaging the engine.


Steam Engine

The term combustion chamber is also used to refer to an additional space between the firebox and boiler in a steam locomotive. This space is used to allow further combustion of the fuel, providing greater heat to the boiler.

Sleeve valve

The sleeve valve is a type of valve mechanism for internal combustion piston engines which have traditionally relied on the more common poppet valve.

A sleeve valve consists of one or more machined sleeves that fit within a piston engine's cylinders and are designed so as to move so that their openings align with the cylinder's inlet and exhaust ports at the appropriate stages in the engine's cycle.

Sleeve valves saw use in some pre-World War II luxury, sports cars and the Willys-Knight car and light truck, and saw substantial use in 1940s aircraft engines such as the Napier Sabre and Bristol Hercules and Centaurus, but they subsequently fell from use due to advances in poppet-valve technology (sodium cooling) and to their tendency to burn considerable amounts of lubricating oil or to seize due to lack of it.



Disadvantages of poppet valves

In a standard internal combustion engine, the poppet valves are opened by the a shaped cam acting on the top of the valve, while the valves are closed by a spring wrapped around the valve stem.

The main problem with this system is that as the RPM of the engine increases, the speed at which the valve moves also increases, increasing the loads involved due to the inertia of the valve, which has to be opened quickly, brought to a stop, then reversed in direction and closed and brought to a stop again. Large valves that allow good air-flow have considerable mass and require a strong spring to overcome the opening inertia. At some point, the valve inertia overwhelms the spring and stops following the cam profile, closing well after the cam lobe has moved away. This "valve float" can eventually cause the valve to not close at all before the cam comes around to open it again and in some engines the piston may even collide with the valve.

The desmodromic system as used by Ducati in some of its motorcycle engines uses mechanical methods to close the valve, but this system requires precision engineering and is markedly more expensive than spring-closed valves.


Sleeve valve description

As its name implies, the sleeve valve is constructed as one or more sleeves that fit around the piston inside the cylinder wall. Ports (holes) in the side of the cylinder replace the more normal intake and exhaust ports on the head, and similar apertures in the sleeve(s) open and close the ports by being rotated into position.

In some engines each sleeve has a gear ring on the bottom that runs in a channel and a small cut in the cylinder wall exposes the gear so that the sleeve can be turned, alternatively the sleeves are operated by a crank driven from the crankshaft, with the sleeve moving in a circular path opening the cylinder ports in the upper part of the circle.

The advantage of the sleeve valve is that very large port openings can be arranged that increase the volumetric efficiency of the cylinder and the combustion chamber formed with the sleeve at the top of its stroke is almost perfect for complete, and detonation-free, combustion of the charge.

Another design involves a reduced height sleeve placed beneath the cylinder head. This has the advantage of being easier to construct, as it does not need to be strong enough to withstand the forces generated by a piston moving within it.


Advantages

No springs are involved in the sleeve valve system, therefore the power needed to operate the valve remains largely constant with the engine's RPM meaning that the system can be used at very high speeds with no penalty for doing so. In addition, the camshaft, pushrods, or rockers can be dispensed with, as the sleeve valves are generally driven by a single gear running directly off the driveshaft. For an aircraft engine this produced desirable reductions in weight and complexity.

An additional advantage of the system is that the size of the ports can be readily controlled. This is of importance when an engine runs over a wide range of RPM, as the speed at which air can enter and exit the cylinder is defined by the size of the duct leading to the cylinder and varies according to the cube of the RPM. In other words, at higher RPM the engine typically requires larger ports that remain open for a greater proportion of the cycle, something that is fairly easy to arrange with sleeve valves, but prohibitively difficult in a poppet valve system.

A minor advantage includes the fact that the cylinder head is not required to house valves, therefore allowing the sparkplug to be placed in the best possible location for efficient ignition of the combustion mixture.


Disadvantages

The sleeve valve has one major disadvantage, in that perfect sealing is difficult. In a poppet valve engine the piston possesses piston rings (often at least 3 and sometimes as many as 8) which form a seal with the cylinder bore, and during the "breaking in" period any imperfections in one are scraped into the other resulting in a good fit. This type of "breaking in" is not possible on a sleeve valve engine however, because the piston and sleeve move in different directions and in some systems even rotate in relation to one another. In the 1940s this was not a major concern because the poppet valves of the time typically leaked appreciably more.


Modern usage

The sleeve valve has begun to make something of a comeback, due to modern materials and newer and dramatically better engineering tolerances and construction techniques which produce a sleeve valve that leaks very little oil. However, most advanced engine research is concentrated on entirely different designs of internal combustion engine such as the rotary engine, as opposed to improvements to existing engines such as the sleeve valve.


History

The sleeve valve principle was invented in 1903 by the American inventor Charles Yale Knight. Although he was initially unable to sell his Knight Engine in the US, a trip to Europe secured several luxury car firms as customers willing to pay his expensive premiums. He first patented the design in Britain in 1908.

Among the companies using Knight's technology were Gabriel Voisin (in his Avions Voisin cars), Daimler (in their V-12 'Double Six'), and Belgium's Minerva company.

Upon Knight's return to America he was able to get some firms to use his design; here his brand name was Silent Knight (1905-1907) — the selling point was that his engines were quieter than those with standard poppet valves. The best known of these were the Stearns Company of Cleveland, which sold a car named the Stearns-Knight, and the Willys firm which offered a car called the Willys-Knight.

A number of sleeve valve aircraft engines were developed following a seminal 1927 research paper from the RAE by Harry Ricardo. This paper outlined the advantages of the sleeve valve, and suggested that poppet valve engines would not be able to offer power outputs much beyond 1500 hp (1,100 kW). Napier and Bristol began the development of sleeve valve engines that would eventually result in two of the most powerful piston engines in the world, the Napier Sabre and Bristol Centaurus.

Following World War II the sleeve valve disappeared from use, as the previous problems with sealing and wear on poppet valves had been remedied by the use of better materials, and the inertia problems with the use of large valves were reduced by using several smaller valves instead, giving increased flow area and reduced mass.

Poppet valve

A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide. In most applications a pressure differential helps to seal the valve and in some applications also open it.

Presta and Schrader valves used on tires are examples of poppet valves. The Presta valve has no spring and relies on a pressure differential for opening and closing while being inflated.

Poppet valves are used in many industrial process from controlling the flow of rocket fuel to controlling the flow of milk.


Internal combustion engine

Poppet valves are used in most piston engines to open and close the intake and exhaust ports in the cylinder head. The valve is usually a flat disk of metal with a long rod known as the valve stem out one end. The stem is used to push down on the valve and open it, with a spring generally used to close it when the stem is not being pushed on. Desmodromic valves are closed by positive mechanical action instead of by a spring, and are used in some high speed motorcycle and auto racing engines, eliminating 'valve float' at high RPM.

For certain applications the valve stem and disk are made of different steel alloys, or the valve stems may be hollow and filled with sodium to improve heat transport and transfer.

The engine normally operates the valves by pushing on the stems with cams and cam followers. The shape and position of the cam determines the valve lift and when and how quickly (or slowly) the valve is opened. The cams are normally placed on a fixed camshaft which is then geared to the crankshaft, running at half crankshaft speed in a four-stroke engine. On high performance engines e.g. used in Ferrari cars, the camshaft is moveable and the cams have a varying height, so by axially moving the camshaft in relation with the engine RPM, also the valve lift varies. See variable valve timing.




Components of a typical, four stroke cycle, DOHC piston engine. (E) Exhaust camshaft, (I) Intake camshaft, (S) Spark plug, (V) Valves, (P) Piston, (R) Connecting rod, (C) Crankshaft, (W) Water jacket for coolant flow.



Valve position

In very early engine designs the valves were 'upside down' in the block, parallel to the cylinders - the so called L-head engine because of the shape of the cylinder and combustion chamber, also called 'flathead engine' as the top of the cylinder head is flat. Although this design makes for simplified and cheap construction, it has two major drawbacks; the tortuous path followed by the intake charge limits air flow and effectively prevents speeds greater than 2,000-2,500 RPM, and the travels of the exhaust through the block lead to excessive overheating under sustained heavy load. This design therefore evolved into 'Intake Over Exhaust', IOE or F-head, where the intake valve was in the block and the exhaust valve was in the head; later both valves moved to the head.

In most such designs the camshaft remained relatively near the crankshaft and the valves were operated through pushrods and rocker arms. This led to significant energy losses in the engine, but was simpler, especially in a V engine where one camshaft can actuate the valves for both cylinder banks; for this reason, pushrod engine designs persisted longer in these configurations than others.

More modern designs have the camshaft on top of the cylinder head, pushing directly on the valve stem (again through cam followers), a system known as overhead camshaft; if there is just one camshaft, this is a single overhead cam or SOHC engine. Often there are two camshafts, one for the intake and one for exhaust valves, creating the dual overhead cam, or DOHC. The camshaft is driven by the crankshaft - through gears, a chain or in modern engines with a rubber belt.



Valve wear

In the early days of engine building, the poppet valve was a major problem. Metallurgy was not what it is today, the rapid opening and closing of the valves against the cylinder heads led to rapid wear. They would need to be re-ground every two years or so, in an expensive and time consuming process known as a valve job. Adding tetra-ethyl lead to the petrol reduced this problem to some degree as the lead would coat the valve seats, hardening the metal. Valve seats made of improved alloys such as stellite have generally made this problem disappear completely and making leaded fuel unnecessary.

Hot bulb engine

The hot bulb engine is a type of internal combustion engine; more specifically, it is a compression ignition engine, in which the fuel is ignited by being suddenly exposed to high temperature and the pressure of a compressed gas, rather than by a separate source of ignition, such as a spark plug, as is the case in the gasoline engine.

It was invented by Herbert Akroyd Stuart in the end of the 19th century. The first prototypes were built in 1886 and production started in 1891 by Richard Hornsby & Sons of Grantham, Lincolnshire, England under the title Hornsby Akroyd Patent Oil Engine under licence. It was later developed in USA by the German emigrants Miez and Weiss by combining it with the two-stroke engine developed by Joseph Day. Similar engines, for agricultural and marine use, were built by Bolinder in Sweden. Bolinder is now part of the Volvo group.

Akroyd-Stuart's compression ignition engine (compared to spark-ignition) was invented two years earlier than Rudolf Diesel's better-known engine working on similar principles.

The engines were usually one cylinder, four-stroke units, although following Miez & Weiss' developments in the USA, 2-stroke versions were constructed.




Operation and working cycle

The hot-bulb engine shares its basic layout with nearly all other internal combustion engines, in that it has a piston inside a cylinder connected to a flywheel via a connecting rod and crankshaft. The flow of gases through the engine is controlled by valves. The majority operate on the standard 4-stroke cycle of an Induction Stroke, a Compression Stroke, a Power Stroke and an Exhaust Stroke.

The main feature of the hot-bulb engine is the vaporiser or hot-bulb, a chamber usually cast into the engine block and attached to the main cylinder by a narrow opening. Prior to starting the engine from cold, this vaporiser is heated externally by a blow-lamp or slow-burning wick (on later models sometimes electric heating or pyrotechnics was used) for as much as half an hour. The engine is then turned over, usually by hand but sometimes by compressed air or an electric motor.

Air is drawn into the cylinder through the intake valve as the piston descends (The Induction Stroke). During the same stroke, fuel is injected into the hot-bulb by a mechanical jerk-pump through a nozzle. Through the action of the injector and the heat of the hot-bulb, the fuel instantly vapourises. The air in the cylinder then forced through the top of the cylinder as the piston rises (The Compression Stroke), through the opening into the hot-bulb, where it is compressed and therefore its temperature rises. The vaporised fuel mixes with the compressed air and ignites due to the heat of the compressed air and the heat applied to the hot-bulb prior to starting. The fuel ignites, driving the piston down (The Power Stroke). The piston's action is converted to a rotary motion by the crankshaft which drives the flywheel, to which equipment can be attached for work to be performed. The flywheel also conserves momentum to turn the engine over the three strokes when power is not being produced. The piston rises again and the exhaust gases are expelled through the exhaust valve (The Exhaust Stroke). The cycle then starts again.

Once the engine is running, the heat of compression and ignition maintains the hot-bulb at the necessary temperature and the blow-lamp or other heat source can be removed. From this point the engine requires no external heat and requires only a supply of air, fuel oil and lubricating oil to run. The fact that the engine could be left unattended for long periods whilst running made hot bulb engines popular choices for powering generators and pumps.




Advantages

At the time the hot-bulb engine was invented, its great attractions were its economy, simplicity and ease of operation in comparison to the steam engine, then the dominant source of power in industry. Steam engines achieved an average thermal efficiency (the amount of heat generated that is actually turned into useful work) of around 6%. Hot-bulb engines could easily achieve 12% thermal efficiency.

The hot-bulb engine is much simpler than the steam engine to construct and operate. Steam engines require at least one person to monitor the boiler and add water and fuel as needed. If fitted with automatic lubrication systems and a governor to control the fuel supply, a hot-bulb engine could be left unattended for hours at a time once running.

Another attraction was their safety. A steam engine, with its exposed fire and hot boiler, steam pipes and working cylinder could not be used in flammable conditions such as munitions factories or fuel refineries. Hot-bulb engine also produced cleaner exhaust fumes. A big danger with the steam engine was that if the boiler pressure grew too high and the safety valve failed, a highly dangerous explosion could occur (although this was a relatively rare occurrence by the time the hot-bulb engine was invented). A more common problem was that if the water level in the boiler of a steam engine was allowed to drop too low, the internal structure of the boiler could collapse or melt, also causing dangerous release of high pressure gas. If a hot bulb engine ran out of fuel, it would simply stop. The cooling water was usually a closed circuit, so no water loss would occur unless there was a leak. If the cooling water ran low, the engine would seize through overheating- a major problem, but it carried no danger of explosion.

Compared to both steam and gasoline (petrol) engines, hot-bulb engines are simpler and therefore have less potential problems. There is no electrical system as found on a petrol engine, and no external boiler and steam system as on a steam engine.

A big attraction with the hot-bulb engine was its ability to run on a wide range of fuels. Even poor-burning fuels could be used since a combination of vaporiser- and compression-ignition meant that such fuels could be made to combust. The usual fuel used was Fuel Oil, similar to modern-day diesel, but natural gas, kerosene, paraffin, crude oil, vegetable oil, creosote and even in some cases coal dust were used in hot-bulb engines. This made the hot-bulb engine very cheap to run, since it could be run on cheaply available fuels. Some operators even ran engines on used engine oil, thus providing almost free power. Recently, this multi-fuel ability has led to an interest in using hot bulb engines in developing nations where they can be run on locally produced biofuel.

Due to the lengthy pre-heating time, hot-bulb engines were nearly always guaranteed to start quickly, even in extremely cold condtions. This made them popular choices in cold regions such as Canada and Scandinavia, where steam engines were not viable but early gasoline and diesel engines could not be relied on to operate.




Uses

The reliability of hot-bulb engine, their ability to run on many fuels and the fact that they can be left running for hours or days at a time made them extremely popular with agricultural and forestry users, where they were used for pumping and powering milling, sawing and threshing machinery. Hot-bulb engines were used on road-rollers and tractors.

J.V. Svensons Motorfabrikk, i Augustendal in Sweden used hot bulb engined in their Typ 1 motor plough, produced from 1912 to 1925. Munktells Mekaniska Värkstads AB, in Eskilstuna, Sweden, produced agricultural tractors with hot bulb engines from 1913 onwards. Heinrich Lanz Mannheim AG, in Mannheim, Germany, started to use hot bulb engines in 1921, in the Lanz Bulldog HL. Other well known tractor manufacturers that used bulb engines were Landini in Italy, HSCS in Hungary and SFV in France.

A limitation of the design of the engine was that it could only run over quite a narrow (and slow) speed band, typically 50-150 R.P.M.. This made the hot-bulb engine difficult to adapt to automotive uses other than vehicles such as tractors, where speed was not a major requirement. This limitation was of little consequence for stationary applications, where the hot-bulb engine was very popular.

Owing to the lengthy pre-heating time, hot-bulb engines only found favour with users who needed to run engines for long periods of time, where the pre-heating process only represented a small percentage of the overall running period. This included marine use (especially in fishing boats), electricity generation (especially in remote areas where coal was not easily available for steam engines) and pumping duties.

The engines were also used in areas where the fire of a steam engine would be an unacceptable fire risk. Akroyd-Stuart developed the world's first oil-engined locomotive (the 'Lachesis') for the Woolwich Arsenal, where the use of locomotives had previously been impossible due to the risk. Hot-bulb engines proved very popular for industrial engines in the early 20th century, but lacked the power to be used in anything larger.




Replacement

From around 1910, the diesel engine was improved dramatically, with more power being available at greater efficiencies than the hot-bulb engine could manage (Diesel engines can achieve nearly 50% efficiency if designed with maximum economy in mind). Diesel engines offered greater power for a given engine size due to the more efficient combustion method (they had no hot-bulb, relying purely on compression-ignition) and greater ease of use as they required no pre-heating.

The hot-bulb engine was limited in its scope in terms of speed and overall power-to-size ratio. To make a hot-bulb engine capable of powering a ship or locomotive, it would have been prohibitively large and heavy. The hot-bulb engines used in Landini tractors were as much as 20-litres in capacity for relatively low power outputs. Hot-bulb engines are difficult to make in multi-cylinder versions as well as creating even combustion throughout the multiple hot-bulbs is a complex business. The hot-bulb engine's low compression ratio in comparison to diesel engines limited its efficiency, power output and speed. Most hot-bulb engines could run at a maximum speed of around 100 R.P.M., whilst by the 1930s diesel engines capable of 2,000 R.P.M. were being built. Also, due to the design of hot bulb and the limitatations of current technology in regards to the injector system, most hot-bulb engines were single-speed engines, running at a fixed speed, or in a very narrow speed range. Diesel engines can be designed to operate over a much wider speed range, making them more versatile. This made these medium-sized diesels a very popular choice for use in generator sets, replacing the hot-bulb engine as the engine of choice for small-scale power generation. The Hot tube engine addresses the speed limitation and gave great flexibility in operation, although the solution induced a source of weakness in the design.

With the development of small-capacity, high-speed diesel engines in the 1930s and 1940s, hot-bulb engines fell dramatically out of favour. The last large-scale manufacturer of hot-bulb engines stopped producing them in the 1950s and they are now virtually extinct in commercial use, except in very remote areas of the developing world.

Ignoring the obvious differences (electrical heating, differing fuels, high RPMs - at least in the small model aircraft types) the modern Glow Plug engine could be considered the latest incarnation of these "hot spot" ignition based engines.




Differences from the Diesel Engine

The hot-bulb engine is often confused with the diesel engine, and it is true that the two engines are very similar. Aside from the obvious lack of a hot-bulb vaporiser in the diesel engine, the main differences are that:

* The hot-bulb engine uses both compression-ignition and the heat retained in the vaporiser to ignite the fuel.

* The diesel engine uses just compression-ignition to ignite the fuel, and it operates at pressures many times higher than the hot-bulb engine.

Due to the much greater and longer-term success of the diesel engine, today hot-bulb engines are sometimes called 'semi-diesels' because they partly use compression-ignition in their cycle.


There is also a detail difference in the timing of the fuel injection process:

* In the hot-bulb engine, fuel is injected into the vapouriser during the Induction Stroke as air is drawn into the cylinder.

* In the diesel engine, fuel is injected into the cylinder in the final stages of the Compression Stroke.

However, Diesel's original engine design used compressed air to blast the fuel into the cylinder. This complex and heavy system limited the speed the engine could run at and the minimum size a diesel engine could be built to. This was needed to inject fuel under sufficient pressure for it to enter the highly compressed air in the cylinder. In hot-bulb engines fuel is injected before compression takes place, allowing a lighter, more accurate injection system to be used. Only when Akroyd-Stuart's mechanical pump-and-injector system that he developed for his hot-bulb engine was adapted by Robert Bosch for use in diesel engines (by making the system run at a much higher pressure) were high-speed diesel engines practical.

Four-stroke cycle

The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today (cars and trucks, electrical generators, etc). The Thermodynamics cycles used in internal combustion reciprocating engines are the Otto Cycle (the ideal cycle for spark-ignition engines) and the Diesel Cycle (the ideal cycle for compression-ignition engines). The Otto Cycle consists of adiabatic compression, heat addition at constant volume, adiabatic expansion and rejection of heat at constant volume. It was conceptualized by the French engineer, Alphonse Beau de Rochas in 1862 and independently, by the German engineer Nicolaus Otto in 1876

The Otto cycle

The Otto cycle is characterized by four strokes, or straight movements alternately, back and forth, of a piston inside a cylinder:

1. intake (induction) stroke

The intake stroke (A.K.A the induction stroke) in relation to an internal combustion engine is the downward stroke of the piston creating a partial vacuum that draws a fuel/air mixture into the combustion chamber.


2. compression stroke

The compression stroke is the second of four stages in an otto cycle or diesel cycle internal combustion engine.

In this stage, the air is compressed to the top of the cylinder by the piston until it is either ignited by a spark plug as in an otto engine or, as in the case of a diesel engine, reaches the point at which the fuel spontaneously combusts, forcing the piston back down.

Compression serves to increase the proportion of energy which can be extracted from the hot gas and should be as high as is practical for a given application.



3. power (combustion) stroke

A power stroke is, in general, the stroke of a cyclic motor which generates force. It is used in describing mechanical engines and molecular motors such as ATP synthase. Many types of motors can be simply described by first, intake stroke (intake of fuel, e.g. gasoline, ATP, etc.) then power stroke and last exhaust stroke (exhaustion of what's left of the fuel which is now in a low energy state), possibly with some steps in between such as the compression stroke in four-stroke cycle engines and then repeating the cycle.

In muscles, the power stroke is the stage of muscle contraction when the cross-bridge (connecting the actin in the thin filament to the myosin in the thick filament) moves towards the H-zone, thus causing the muscle fiber to contract. The energy for this process comes from ATP present in the myosin prior to contraction.

In sports, too, often a swing with a lot of force will be called a power stroke. For example, this is used in canoeing to describe a powerful motion with a paddle.



4. exhaust stroke

The exhaust stroke is the fourth of four stages in an internal combustion engine cycle. In this stage gases remaining in the cylinder from the fuel ignited during the compression step are removed from the cylinder through a valve at the top of the cylinder. The gases are forced up to the top of the cylinder as the piston rises and are pushed through the opening which then closes to allow fresh air/fuel mixture into the cylinder so the the process can repeat itself.



The cycle begins at top dead centre (TDC), when the piston is furthest away from the crankshaft. On the first stroke (intake) of the piston, a mixture of fuel and air is drawn into the cylinder through the intake (inlet) port. The intake (inlet) valve (or valves) then close(s) and the following stroke (compression) compresses the fuel-air mixture.

The air-fuel mixture is then ignited, usually by a spark plug for a gasoline or Otto cycle engine or by the heat and pressure of compression for a Diesel cycle or compression ignition engine, at approximately the top of the compression stroke. The resulting expansion of burning gases then forces the piston downward for the third stroke (power) and the fourth and final stroke (exhaust) evacuates the spent exhaust gases from the cylinder past the then-open exhaust valve or valves, through the exhaust port.

Twingle engine

The Twingle engine is a small-capacity two-stroke petrol engine. It uses two pistons, one of which controls the inlet ports, the other the exhaust ports. These run in two parallel cylinder bores but share a single combustion chamber, spark plug and cylinder head.

The first Twingle engine was designed by Alberto Garelli, who patented the design in 1912. His design had a forked connecting rod with two small-ends and one big-end, and had a capacity of 346 cc. Garelli produced some motorcycles with this engine, but was more successful with more conventional designs.

Two versions of the Twingle engine were produced by Austrian moped manufacturer Puch. The earlier, based on the Garelli design, was produced from 1923. From 1949 this was replaced by a design by Giovanni Marcellino, with different sized pistons and a more elaborate connecting-rod setup. The Marcellino engine continued in production until 1970. It was complex and expensive to produce compared to a conventional single cylinder engine, and heavier for the same power output. Its only advantage was claimed to be fuel efficiency.

Both the Garelli and Marcellino engines are sometimes described as two-cylinder and sometimes as one-cylinder. Possibly as a result, the Twingle is sometimes confused with the opposed piston two-stroke diesel engine design, which has two pistons per cylinder at opposite ends of the cylinder, and no cylinder head at all. Like the Twingle, the opposed piston design uses one piston to control the inlet ports and another the exhaust, but there the similarity ends.

It is easy to see how a Twingle engine could be mistaken for a single cylinder engine. It looks, sounds and in most ways performs like one, and has only one spark plug, but in fact the Twingle has two pistons each in its own separate cylinder bore.

Two-stroke Compared with four-stroke engines

Two-stroke engines have several marked disadvantages that have largely precluded their use in automobiles (although there was some use, such as in historic Saabs and DKWs and until recently in several automobiles produced in the Eastern bloc, including Trabants and Wartburgs, among others) and are reducing their prevalence in the above applications. Firstly, they require much more fuel than a comparably powerful four-stroke engine due to less efficient combustion. The burning oil, and the less efficient combustion, makes their exhaust far smellier and more damaging than a four-stroke engine, thus struggling to meet current emission control laws. They are noisier, partly due to the more penetrating high-frequency buzzing and partly due to the fact that muffling them reduces engine power far more than on a four-stroke engine (high-performance two-stroke engine exhausts are tuned by determining the resonant frequency of the exhaust systems and exploiting it to top-up the fuel air charge just before the cylinder port closes). Finally, they are considered less reliable and durable than four stroke engines.

Two-stroke diesel engines were used in trucks, with a notable example being the 1954 Commer. This engine was the Rootes TS3 (TillingStevens), a horizontal, opposed piston, three-cylinder. The General Motors EMD diesel powered locomotives have been using 2-stroke engines since the 1930s. These engines have up to 16 cylinders (with a total displacement of approximately 11,000 cubic inches). Typical power output would be 4,300 hp. The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient power plant in the world today and is used in ships.

A notable area of use today is in small displacement motorcycles, mostly in off-road "dirt-bikes", and scooters, where their higher power-to-weight ratio, and smaller size outweigh their aforementioned disadvantages.

There are more elaborate possible two-stroke engine configurations, but these often have enough complications that they do not outperform comparable four-stroke engines. New two-stroke designs rely on electronically-controlled fuel injection, oil injection and other design improvements to reduce pollution and increase fuel efficiency. However, such systems increase the cost of the engines to the point that for small systems simple four-stroke engines are most cost-effective. Many large manufacturers, including Ford and Honda are still actively researching ways to build practical and clean two strokes for automotive use.

Two-stroke diesel engines

A two-stroke cycle has also been used for some diesel engines. As the fuel is injected directly into the cylinder, the lubrication of the crankshaft must be independent in these engines. There is no mixing of lubricating oil into the fuel.

There are three patterns. Some modern designs differ from the gasoline two-stroke cycle in that they have intake and exhaust valves in the cylinder head, exactly like a four-stroke engine. In these engines, the two-stroke cycle is used to improve power-to-weight ratio and/or reduce the engine speed to increase reliability. This pattern, the Clark cycle, is common in truck, railroad locomotive and machinery engines.

Other engines have used the same ported arrangement as the gasoline two-stroke, although the charge air is generally delivered under pressure from a blower through ducting rather than through the crankcase. Examples are the Junkers Jumo 205 and Napier Deltic high-speed opposed piston engines.

A third pattern uses the induction method of the gasoline two-stroke, but with an exhaust valve in the cylinder head. Large marine diesels commonly use this arrangement. These engines commonly also use a crosshead bearing, which together with a sliding seal on the piston rod allows the air path to be separated from the crankshaft while still using the piston movement as an air pump.

The simpler stroke in the fully valved diesel two-stroke cycle is the compression stroke; both valves are closed, and the rising piston compresses the air, heating it. At the top of the stroke, diesel fuel is injected into the cylinder, where it ignites and burns. The hot, high pressure gases produced by the combustion push against the piston as it descends in the initial part of the second stroke, delivering power. At this point, both valves are still closed. When the piston nears the bottom of the stroke, the exhaust valve opens, and the exhaust gases, still under pressure, rush out. The intake valve then opens. Air under pressure rushes into the cylinder, blowing out the remainder of the exhaust gases. The exhaust valve closes at that point, and shortly after that, and at about bottom dead center, so does the intake valve.

If the crankcase is not used as an air pump, some other means of forced induction is required, and is often used for efficiency in any case. The intake air must be under pressure, since the engine does not have an induction stroke and cannot suck the air in by itself. A low-pressure supercharger (blower) is needed at minimum, but many are turbocharged. Crossley two-stroke diesels were equipped with "exhaust-pulse pressure-charging" whereby surplus air in the exhaust manifold was forced back into the cylinder by the exhaust-pulse from a neighbouring cylinder.

The diesel two-stroke generally lacks the inefficiency and pollution problems of the gasoline two-stroke, since no unburned fuel, only air, can get blown out of the exhaust valve before it closes. Also, there is no mixing of lubricant with the fuel.

Two-stroke Engine Basic Operation

The two-stroke engine is simple in construction, but complex dynamics are employed in its operation. A typical simple two-stroke contains a piston whose face is shaped, an exhaust port on one side of the cylinder, and a transfer port on the other side. The downward movement of the piston first uncovers the exhaust port, allowing most of the exhaust to be expelled, and then uncovers the transfer port through which an air-fuel mixture (the fuel normally has some oil mixed in) is let into the cylinder. The piston then moves upwards, compressing the mixture which is ignited by a spark plug, driving the piston back down.


In more detail:

Intake and compression

The rising piston creates a partial vacuum in the sealed crankcase. A connection (inlet port) between the crankcase and the carburetor is uncovered by the piston as it rises, and the air-fuel mixture is sucked into the crankcase. At the same time, the air-fuel mixture already in the cylinder is being compressed as the piston gradually moves up.


Steps of two-stroke cycle:

Expansion stroke:

The piston is at Top Dead Center (TDC)
Crank is at 0 or 360°.

In real engines the process is completed from 0 to 150° but in this model it is completed at 120°.


Intake/Compression stroke:

The piston moves from Bottom Dead Center (BDC) to TDC.

The intake port is opened and working substance flows in.

Intake gases move inside due to partial vacuum; also, blowers are used to push intake gases in.

The vacuum opens the reed valve (thin flexible sheets made of steel, glass fiber or even carbon fiber) allowing the mixture to enter the crankcase.

The air-fuel mixture already in the cylinder is compressed.
As the piston nears the top of the stroke, the ignition system ignites the charge in the combustion chamber.

In diesel engines, at 11-13° before TDC fuel is injected. Before that point, only air is compressed. Fuel is injected only in the last stage of compression.



Exhaust and scavenging process:

The piston moves from TDC to BDC.

At 120°, the exhaust port is opened and exhaust gases move out of the cylinder due to gas pressure.

After 10-40°, fresh scavenging gases are then let into the cylinder through the transfer port(s).

The air/fuel/oil mixture that was let into the cylinder pushes the exhaust out the exhaust port.

The piston, then, compresses the air/fuel/oil mixture and lets left over exhaust out.



Power and exhaust

When the piston reaches the top of its stroke, the mixture is ignited, and the piston is forced down by the rapidly expanding combustion gases.

As the piston descends, a hole in the side of the cylinder connected to the exhaust pipe (exhaust port) is opened, allowing the burned gases to escape.

Furthermore, the descending piston closes the inlet port and pressurizes the crankcase. This also pushes some mixture from the crankcase back to the inlet tract, causing the reed valve to close and preventing the mixture from entering the air filter.

The air fuel mixture is forced into passageways that connect the crankcase to the cylinder. Holes connecting these passages to the upper cylinder (transfer ports) are uncovered by the descending piston and air-fuel mixture is forced into the upper cylinder. The transfer ports are just a bit lower than the top of the exhaust port, so there is a period of time when fresh air-fuel mixture is coming in while exhaust is leaving. The incoming fresh charge assists in forcing the exhaust gas out.

As the piston reaches the bottom and then starts to rise again, the transfer ports are closed by the piston and the air/fuel mixture is compressed. The next cycle starts.



Design issues

A major problem with the two-stroke engine has been the short-circuiting of fresh charge from intake to exhaust which increases fuel consumption and emissions of unburned hydrocarbons. The cylinder ports and piston top are shaped to minimize this mixing of the intake and exhaust flows. Furthermore, a tuned pipe with an expansion chamber provides back pressure at just the right time to push fresh air-fuel mixture sneaking out the exhaust back in again.

The major components of two-stroke engines are tuned so that optimum airflow results. Intake and exhaust pipes are tuned so that resonances in airflow give better flow.

Two-stroke engines typically mix lubricants, two-stroke oil, with their fuel (either manually at refueling or by injecting oil into the fuel stream); this mixture lubricates the cylinder, crankshaft and connecting rod bearings. The lubricant is subsequently burned, resulting in undesirable emissions. An independent lubrication system from below, as is used in four-stroke designs, cannot be used in the above-described engine design, since the crankcase is being used to hold the air-fuel mixture.

This problem has been addressed in newer engines which employ gasoline direct injection, similar to diesel two-strokes.

Two-stroke cycle

The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by completing the same four operations (intake, compression, power, exhaust) in only two strokes (linear movements of the piston) rather than four. Thus, there is a power stroke per piston for every engine revolution, instead of every second revolution. Wth proper design, a two-stroke engine can be arranged to start and run in either direction, and many engines have been built to do this. Engines not designed to run in reverse are still capable of doing it; however running one in reverse for long periods might cause internal damage. This is due to piston throw and piston pin offset, a design feature of all modern piston engines that reduces piston slap. Ignition timing will also be severely retarded in reverse and oil pumps will not function backwards.



Two-stroke engines are used mostly among the smallest and largest reciprocating powerplants, but less commonly among medium-sized ones.

The smallest gasoline engines are usually two-strokes. They are commonly used in outboard motors, high-performance, small-capacity motorcycles, mopeds, scooters, snowmobiles, karts, model airplanes (and other model vehicles) and motorized garden appliances like string trimmers, chainsaws and lawnmowers. In each application, they are popular because of their simple design (and therefore, low cost) and very high power-to-weight ratios (because the engine has twice as many combustions per second as a four-stroke engine revolving at the same speed). Two-stroke engines often have a simple lubrication system in which oil is mixed with the fuel, (then known as 'petroil' from "petrol" + "oil") and therefore reaches all moving parts of the engine. For this reason, for handheld devices, they have the advantage of working in any orientation, as there is no oil reservoir dependent upon gravity.

Two-stroke cycles have also been used in diesel engines, notably opposed piston designs, low speed units such as large marine engines, and V8 engines for trucks and heavy machinery.

Crude oil engine

The crude oil engine is a type of internal combustion engine similar to the hot bulb engine. A crude oil engine could be driven by all sorts of oils such as engine waste oil and vegetable oils. Anything could be used as fuel, even peanut oil and butter if it was necessary. Like hot bulb engines, crude oil engines were mostly used as stationary engines or in boats. They can run for a very long time, for instance at the world fair in Milano in 1907, a FRAM engine was started and it wasn't stopped until the exhibition was over one month later. A crude oil engine is a low RPM engine dimensioned for constant running and can last for a very long time if maintained properly.

It was later replaced by the diesel engine.

History Of Internal Combustion Engines

The first internal combustion engines did not have compression, but ran on what air/fuel mixture could be sucked or blown in during the first part of the intake stroke. The most significant distinction between modern internal combustion engines and the early designs is the use of compression and in particular of in-cylinder compression.

* 1509: Leonardo da Vinci described a compression-less engine. (His description may not imply that the idea was original with him or that it was actually built.)

* 1673: Christiaan Huygens described a compression-less engine.

* 1780's: Alessandro Volta built a toy electric pistol in which an electric spark exploded a mixture of air and hydrogen, firing a cork from the end of the gun.

* 17th century: English inventor Sir Samuel Morland used gunpowder to drive water pumps.

* 1794: Robert Street built a compression-less engine whose principle of operation would dominate for nearly a century.

* 1806: Swiss engineer François Isaac de Rivaz built an internal combustion engine powered by a mixture of hydrogen and oxygen.

* 1823: Samuel Brown patented the first internal combustion engine to be applied industrially. It was compression-less and based on what Hardenberg calls the "Leonardo cycle," which, as this name implies, was already out of date at that time. Just as today, early major funding, in an area where standards had not yet been established, went to the best showmen sooner than to the best workers.

* 1824: French physicist Sadi Carnot established the thermodynamic theory of idealized heat engines. This scientifically established the need for compression to increase the difference between the upper and lower working temperatures, but it is not clear that engine designers were aware of this before compression was already commonly used. It may have misled designers who tried to emulate the Carnot cycle in ways that were not useful.

* 1826 April 1: The American Samuel Morey received a patent for a compression-less "Gas Or Vapor Engine".

* 1838: a patent was granted to William Barnet (English). This was the first recorded suggestion of in-cylinder compression. He apparently did not realize its advantages, but his cycle would have been a great advance if developed enough.

* 1854: The Italians Eugenio Barsanti and Felice Matteucci patented the first working efficient internal combustion engine in London (pt. Num. 1072) but did not get into production with it. It was similar in concept to the successful Otto Langen indirect engine, but not so well worked out in detail.

* 1860: Jean Joseph Etienne Lenoir (1822 - 1900) produced a gas-fired internal combustion engine closely similar in appearance to a horizontal double-acting steam beam engine, with cylinders, pistons, connecting rods, and flywheel in which the gas essentially took the place of the steam. This was the first internal combustion engine to be produced in numbers. His first engine with compression shocked itself apart.

* 1862: Nikolaus Otto designed an indirect-acting free-piston compression-less engine whose greater efficiency won the support of Langen and then most of the market, which at that time, was mostly for small stationary engines fueled by lighting gas.

* 1870: In Vienna Siegfried Marcus put the first mobile gasoline engine on a handcart.

* 1876: Nikolaus Otto working with Gottlieb Daimler and Wilhelm Maybach developed a practical four-stroke cycle (Otto cycle) engine. The German courts, however, did not hold his patent to cover all in-cylinder compression engines or even the four stroke cycle, and after this decision in-cylinder compression became universal.

* 1879: Karl Benz, working independently, was granted a patent for his internal combustion engine, a reliable two-stroke gas engine, based on Nikolaus Otto's design of the four-stroke engine. Later Benz designed and built his own four-stroke engine that was used in his automobiles, which became the first automobiles in production.

* 1882: James Atkinson invented the Atkinson cycle engine. Atkinson’s engine had one power phase per revolution together with different intake and expansion volumes making it more efficient than the Otto cycle.

* 1891 - Herbert Akroyd-Stuart builds his oil engine leasing rights to Hornsby of England to build engines. They build the first cold start, compression ignition engines. In 1892 they install the first ones in a water pumping station.

* 1892: Rudolf Diesel develops his Carnot heat engine type motor burning powdered coal dust.

* 1893 February 23: Rudolf Diesel received a patent for the diesel engine.

* 1896: Karl Benz invented the boxer engine, also known as the horizontally opposed engine, in which the corresponding pistons reach top dead centre at the same time, thus balancing each other in momentum.

* 1900: Rudolf Diesel demonstrated the diesel engine in the 1900 Exposition Universelle (World's Fair) using peanut oil.

* 1900: Wilhelm Maybach designed an engine built at Daimler Motoren Gesellschaft—following the specifications of Emil Jellinek—who required the engine to be named Daimler-Mercedes after his daughter. In 1902 automobiles with that engine were put into production by DMG.


Applications

Internal combustion engines are most commonly used for mobile propulsion systems. In mobile scenarios internal combustion is advantageous, since it can provide high power to weight ratios together with excellent fuel energy-density. These engines have appeared in almost all automobiles, motorbikes, many boats, and in a wide variety of aircraft and locomotives. Where very high power is required, such as jet aircraft, helicopters and large ships, they appear mostly in the form of gas turbines. They are also used for electric generators and by industry.

Internal combustion engine

The internal combustion engine is anfucken retared engine in which the burning of a fuel occurs in a confined space called a combustion chamber. This exothermic reaction of a fuel with an oxidizer creates gases of high temperature and pressure, which are permitted to expand. The defining feature of an internal combustion engine is that useful work is performed by the expanding hot gases acting directly to cause shitty movement, for example by acting on pistons, rotors, or even by pressing on and moving the entire engine itself.

This contrasts with external combustion engines, such as steam engines, which use the combustion process to heat a separate working fluid, typically water or steam, which then in turn does work, for example by pressing on a steam actuated piston.

The term Internal Combustion Engine (ICE) is almost always used to refer specifically to reciprocating engines, Wankel engines and similar designs in which combustion is intermittent. However, continuous combustion engines, such as Jet engines, most rockets and many gas turbines are also internal combustion engines.


Operation

All internal combustion engines depend on the exothermic chemical process of combustion: the reaction of a fuel, typically with air, although other oxidisers such as nitrous oxide may be employed. Also see stoichiometry.

The most common fuel in use today are made up of hydrocarbons and are derived from petroleum. These include the fuels known as diesel, gasoline and liquified petroleum gas. Most internal combustion engines designed for gasoline can run on natural gas or liquified petroleum gases without modifications except for the fuel delivery components. Liquid and gaseous biofuels, such as Ethanol can also be used. Some can run on Hydrogen.

All internal combustion engines must have a means of ignition to promote combustion. Most engines use either an electrical or a compression heating ignition system. Electrical ignition systems generally rely on a lead-acid battery and an induction coil to provide a high voltage electrical spark to ignite the air-fuel mix in the engine's cylinders. This battery can be recharged during operation using an electricity-generating device, such as an alternator, driven by the engine. Compression heating ignition systems, such as diesel engines and HCCI engines, rely on the heat created in the air by compression in the engine's cylinders to ignite the fuel.

Once successfully ignited and burnt, the combustion products, hot gases, have more available energy than the original compressed fuel/air mixture (which had higher chemical energy). The available energy is manifested as high temperature and pressure which can be translated into work by the engine. In a reciprocating engine, the high pressure product gases inside the cylinders drive the engine's pistons.

Once the available energy has been removed the remaining hot gases are vented (often by opening a valve or exposing the exhaust outlet) and this allows the piston to return to its previous position (Top Dead Center - TDC). The piston can then proceed to the next phase of its cycle, which varies between engines. Any heat not translated into work is normally considered a waste product, and is removed from the engine either by an air or liquid cooling system.


Parts

The parts of an engine vary depending on the engine's type. For a four-stroke engine, key parts of the engine include the crankshaft (purple), one or more camshafts (red and blue) and valves. For a two-stroke engine, there may simply be an exhaust outlet and fuel inlet instead of a valve system. In both types of engines, there are one or more cylinders (grey and green) and for each cylinder there is a spark plug (darker-grey), a piston (yellow) and a crank (purple). A single sweep of the cylinder by the piston in an upward or downward motion is known as a stroke and the downward stroke that occurs directly after the air-fuel mix in the cylinder is ignited is known as a power stroke.

A Wankel engine has a triangular rotor that orbits in an epitrochoidal (figure 8 shape) chamber around an eccentric shaft. The four phases of operation (intake, compression, power, exhaust) take place in separate locations, instead of one single location as in a reciprocating engine.

A Bourke Engine uses a pair of pistons integrated to a Scotch Yoke that transmits reciprocating force through a specially designed bearing assembly to turn a crank mechanism. Intake, compression, power, and exhaust all occur in each stroke of this yoke.

History of engines

Antiquity

Engines using human power, animal power, water power, wind power and even steam power date back to antiquity.

Human power was focused by the use of simple engines, such as the capstan, windlass or treadmill, and with ropes, pulleys, and block and tackle arrangements, this power was transmitted and multiplied. These were used in cranes and aboard ships during Ancient Greece, and in mines, water pumps and siege engines in Ancient Rome. Early oared warships used human power augmented by the simple engine of the lever -- the oar itself. The writers of those times, including Vitruvius, Frontinus and Pliny the Elder, treat these engines as commonplace, so their invention may be far more ancient.

By the 1st century AD, various breeds of cattle and horses were used in mills, using machines similar to those powered by humans in earlier times.

According to Strabo, a water powered mill was built in Kaberia in the kingdom of Mithridates in the 1st century BC. Use of water wheels in mills spread through Europe over the next few centuries. Some were quite complex, with aqueducts, dams, and sluices to maintain and channel the water, and systems of gears, or toothed-wheels made of wood with metal, used to regulate the speed of rotation. In a poem by Ausonius in the 4th century, he mentions a stone-cutting saw powered by water.

Hero of Alexandria demonstrated both wind and steam powered machines in the 1st century, although it is not known if these were put to any practical use.


Modern

English inventor Sir Samuel Morland allegedly used gunpowder to drive water pumps in the 17th century. For more conventional, reciprocating internal combustion engines the fundamental theory for two-stroke engines was established by Sadi Carnot, France, 1824, whilst the American Samuel Morey received a patent on April 1, 1826.

Automotive production has used a range of energy-conversion systems. These include electric, steam, solar, turbine, rotary, and piston-type internal combustion engines. The gasoline internal combustion engine, operating on a four-stroke Otto cycle, has been the most successful for automobiles, while diesel engines are used for trucks and buses. The patent on the design by Otto had been declared void.

Karl Benz led in the development of new engines. In 1878 he began to work on new patents. He concentrated his efforts on creating a reliable gas two-stroke engine, based on Nikolaus Otto's design of the four-stroke engine. Karl Benz showed his real genius, however, through his successive inventions registered while designing what would become the production standard for his two-stroke engine. Benz finished his engine on New Year's Eve and was granted a patent for it in 1879.

In 1896, Karl Benz was granted a patent for his design of the first boxer engine with horizontally-opposed pistons. His design created an engine in which the corresponding pistons reach top dead centre simultaneously, thus balancing each other with respect to momentum. Flat engines with four or fewer cylinders are most commonly boxer engines and are also known as, horizontally-opposed engines. This continues to be the design principle for high performance, automobile racing engines such as Porsches.

Continuance of the use of the internal combustion engine for automobiles is partially due to the improvement of engine control systems (computers) and forced induction (turbos and superchargers), giving modern diesel engines the same power characteristics as gasoline engines. This is especially evident with the popularity of diesel engines in Europe.

The internal combustion engine was originally selected for the automobile due to its flexibility over a wide range of speeds. Also, the power developed for a given weight engine was reasonable; it could be produced by economical mass-production methods; and it used a readily available, moderately priced fuel--gasoline.

In today’s world, there has been a growing emphasis on the pollution producing features of automotive power systems. This has created new interest in alternate power sources and internal-combustion engine refinements that were not economically feasible in prior years. Although a few limited-production battery-powered electric vehicles have appeared, they have not proved to be competitive owing to costs and operating characteristics. In the twenty-first century the diesel engine has been increasing in popularity with automobile owners. However, the gasoline engine, with its new emission-control devices to improve emission performance, has not yet been challenged significantly.

The first half of the twentieth century saw a trend to increase engine power, particularly in the American models. Design changes incorporated all known methods of raising engine capacity, including increasing the pressure in the cylinders to improve efficiency, increasing the size of the engine, and increasing the speed at which power is generated. The higher forces and pressures created by these changes created engine vibration and size problems that led to stiffer, more compact engines with V and opposed cylinder layouts replacing longer straight-line arrangements. In passenger cars, V-8 layouts were adopted for all piston displacements greater than 250 cubic inches (4 litres).

Smaller cars brought about a return a to smaller engines, the four- and six-cylinder designs rated as low as 80 horsepower (60 kW), compared with the standard-size V-8 of large cylinder bore and relatively short piston stroke with power ratings in the range from 250 to 350 hp (190 to 260 kW).

The automobile motor had a bigger range, varying from 1-9 cylinders with corresponding differences in overall size, weight, piston displacement, and cylinder bores. Four cylinders and power ratings from 19 to 120 hp (14 to 90 kW) were followed in a majority of the models. Several three-cylinder, two-stroke-cycle models were built while most engines had straight or in-line cylinders. There were several V-type models and horizontally opposed two- and four-cylinder makes too. Overhead camshafts were frequently employed. The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and '80s saw an increased interest in improved fuel economy which brought in a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency.

Air-breathing engines

Air-breathing engines use atmospheric air to oxidise the fuel carried, rather than carrying an oxidiser, as in a rocket. Theoretically, this should result in a better specific impulse than for rocket engines.

Air-breathing engines include:

* Internal combustion engine
* Jet engine
* Ramjet
* Scramjet
* Pulse detonation engine
* Pulse jet
* Liquid air cycle engine/SABRE

Single cylinder engine

A single cylinder engine, colloquially known as a one-lunger, is an engine configuration consisting of just one cylinder, the simplest arrangement possible for an Otto or Diesel engine. The mounting can be standing, lying or angled.


Pros and Cons

Compared to multi-cylinder engines, single cylinder engines have several advantages, primarily their simple and economical construction. Balance shafts and counterweights on the crankshaft must be used to balance the weight of reciprocating parts, and can be expensive and complicated due to the collective mass of multiple cylinders. Components such as the crank have to be just as strong as in a four-cylinder engine of the same capacity per cylinder, meaning that some parts are effectively four times heavier than they need to be for the total displacement of the engine. This leads to the biggest downside of the single cylinder engine: it develops considerably lower power to weight ratios than a multi-cylinder of the same type.


Uses

Some early automobiles, such as the Cadillac 1906 Model K and 1907 Models L and M used single-cylinder engines. Single cylinder engines were also popular at one time for marine uses. Today the most common configuration is the 50cc-two-stroke Otto seen in so many bikes and scooters. These vehicles allowed the first mass-motorisation in many countries. Most engines used in small portable appliances, such as chainsaws, generators and domestic lawn mowers, usually have one cylinder. Also, the one-lunger is used in working vehicles, motorsports, airplanes, and as an industrial motor.

Piston

In general, a piston is a sliding plug that fits closely inside the bore of a cylinder.

Its purpose is either to change the volume enclosed by the cylinder, or to exert a force on a fluid inside the cylinder.


Internal combustion engine

Most pistons fitted in a cylinder have piston rings. Usually there are two spring-compression rings that act as a seal between the piston and the cylinder wall, and one or more oil control rings below the compression rings. The head of the piston can be flat, bulged or otherwise shaped. Pistons can be forged or cast. The shape of the piston is normally rounded (but can be different, see NR500 ). A special type of cast piston is the hypereutectic piston. The piston is an important component of a piston engine and of hydraulic pneumatic systems.

In an Otto or Diesel engine, the head of the piston forms one wall of an expansion chamber inside the cylinder. The opposite wall, called the cylinder head, contains inlet and exhaust valves for gases.

As the piston moves inside the cylinder, it transforms the energy from the expansion of a burning gas (usually a mixture of petrol or diesel and air) into mechanical power (in the form of a reciprocating linear motion). From there the power is conveyed through a connecting rod to a crankshaft, which transforms it into a rotary motion, which usually drives a gearbox through a clutch.


Ways of making power

There are two ways that a piston engine can make power. These are the two-stroke cycle and the four-stroke cycle. A two stroke engine produces power every stroke, while a four stroke engine produces power every other stroke. Older designs of small two-stroke engines produced more pollution than four stroke engines, however modern two-stroke designs, like the Vespa ET2 Injection utilise fuel-injection and are as clean as four-strokes. Large diesel two-stroke engines, as used in ships and locomotives, have always used fuel injection and produce low emissions. One of the biggest internal combustion engines in the world, the Wärtsilä-Sulzer RTA96-C is a two-stroke; it is bigger than most two-storey houses, has pistons nearly 1 metre in diameter and is one of the most efficient mobile engines in existence. In theory, a four stroke engine has to be larger than a two stroke engine to produce an equivalent amount of power. Two stroke engines are becoming less common in developed countries these days, mainly due to manufacturer reluctance to invest in reducing two-stroke emissions. Traditionally, two stroke engines needed more maintenance, even though they have less moving parts and tended to wear out faster than four stroke engines, however fuel-injected two-strokes achieve better engine lubrication and cooling and reliability should improve considerably.


External combustion engine

A steam engine is another type of piston engine. In most steam engines, the pistons are double acting: steam is alternately admitted to either end of the cylinder, so that every piston stroke produces power. .

Rotary engine

The rotary engine was a common type of internal combustion aircraft engine in the early years of the 20th century. It was also used in a few motorcycles and cars.

In concept, a rotary engine is simple. It is a standard Otto cycle engine, but instead of having an orthodox fixed cylinder block with rotating crankshaft, the crankshaft remains stationary and the entire cylinder block rotates around it. In the most common form, the crankshaft was fixed solidly to an aircraft frame, and the propeller simply bolted onto the front of the cylinder block.

The effect of rotating such a large mass was an inherent large gyroscopic flywheel effect, smoothing out the power and reducing vibration. Vibration had been such a serious problem on other conventional piston engine designs that heavy flywheels had to be added. Because the cylinders themselves functioned as a flywheel, rotary piston engines typically had a power-to-weight ratio advantage over more conventional engines.

Most rotary engines were arranged with the cylinders pointed outwards from a single crankshaft, in the same general form as a radial, but there were also rotary boxer engines and even one cylinder rotaries.



History in aircraft

The first effective rotaries were built by Stephen Balzer, who was interested in the design for two main reasons:

* In order to generate 100 hp (75 kW) at the low rpm at which the engines of the day ran, the pulsation resulting from each combustion stroke was quite large. In order to damp out these pulses, engines needed to mount a large flywheel, which added weight. In the rotary design the engine itself doubled as its flywheel, thus rotaries were lighter than similarly sized engines of regular design.

* The cylinders had good airflow over them even when sitting still, which was an important concern given the alloys they had to work with at the time. Balzer's early engines did not even use cooling-fins, a feature of every other air-cooled design, and one that is complex and expensive to manufacture.

Balzer's first designs were ready for use in 1899, at which time they were the most advanced in the world. Other aircraft engines would not catch up in performance for a decade. He then became involved in Langley's Aerodrome attempts, which bankrupted him while he tried to make much larger versions.

The next major advance in the design was Louis and Laurent Seguin's Gnôme series from 1908. This design was developed from a German single-cylinder stationary engine intended for light industrial use, the Gnom, which the brothers were producing under license from Motorenfabrik Oberursel. They essentially took several Gnom cylinders and combined them on a common shaft to produce a seven-cylinder rotary, the Gnôme Omega No.1 still exists and is in the collection of the Smithsonian's National Air and Space Museum. A production version of the Omega then soon reached the aviation market, still as a 7-cylinder 50 hp (37 kW), which soon reached 80 hp (60 kW), and eventually 110 hp (80 kW). The engine was at this later 80 hp (60 kW) standard when WWI started, as the Gnôme Lambda, and the Gnome quickly found itself being used in a large number of aircraft designs. It was so good that it was licensed by a number of companies, including the German Oberursel firm who designed the original Gnom engine. Oberursel was later purchased by Fokker, whose Gnôme Lambda copy was known as the Oberursel U.I. It was not at all uncommon for French Gnômes to meet German versions in combat.

The Gnôme (and its copies) had a number of features that made it unique, even among the rotaries. Notably, the fuel was mixed and sprayed into the center of the engine through a hollow crankshaft, and then into the cylinders through the piston itself, a single valve on the top of the piston let the mixture in when opened. The valves were counter balanced so that only a small force was needed to open them, and releasing the force closed the valve without any springs. The center of the engine is normally where the oil would be, and the fuel would wash it away. To fix this, the oil was mixed in liberal quantities with the fuel, and the engine spewed smoke due to burning oil. Castor oil was the lubricant of choice, its gum-forming tendency being irrelevant in a total-loss lubrication system. An unfortunate side-effect was that Sopwith Camel pilots inhaled and swallowed a considerable amount of the oil during flight, leading to persistent diarrhoea. Finally, the Gnôme had no throttle or carburetor. Since the fuel was being sprayed into the spinning engine, the motion alone was enough to mix the fuel fairly well. Of course with no throttle, the engine was either on or off, so something as simple as reducing power for landing required the pilot to cut the ignition. "Blipping" the engine on and off gave the characteristic sputtering sound as though the engine was nearly stalling, though it did not stall as quickly as conventional engines due to its great rotational inertia.

Throughout the early period of the war, the power-to-weight ratio of the rotaries remained ahead of that of their competition. They were used almost universally in fighter aircraft, while traditional water cooled designs were used on larger aircraft. The engines had a number of disadvantages, notably very poor fuel consumption, partially because the engine was always "full throttle", and also because the valve timing was often less than ideal. The rotating mass of the engine made it, in effect, a large gyroscope. This could result in tricky handling. The Sopwith Camel, for example, was known to turn very nimbly to the right, but rather sluggishly to the left. Nevertheless, rotaries maintained their edge through a series of small upgrades, and many newer designs continued to use them.

A few of the nine cylinder rotaries managed to accomplish a partially throttleable functionality by switching off either three or six cylinders (or other numbers of them), instead of all nine of them, when the "coupe switch" was depressed to cut the spark. It is believed that both German and Allied WW I rotaries had this ability, as some surviving documentation regarding the Fokker Eindecker shows a rotary selector switch to cut out a selected number of cylinders on its rotary engine. The Gnôme Monosoupape series of engines is known to have this sort of switching available to it, and has been demonstrated long after WW I by a 160 hp Monosoupape powered reproduction Sopwith Camel at Old Rhinebeck Aerodrome while in flight in the 1990s.

As the war progressed, aircraft designers demanded ever-increasing amounts of power. Inline engines were able to meet this demand by improving their RPM, as more "bangs per minute" meant more power delivered. Improvements in valve timing, ignition systems and lighter materials made these higher RPM possible, and by the end of the war the average engine had increased from 1,200 RPM to 2,000. However the rotary was not able to use the same "trick," due to the drag of the cylinders through the air as they spun. For instance, if an early-war model of 1,200 RPM increased to only 1,400, the drag on the cylinders increased 36%, as air drag increases with the square of velocity. At lower speeds the drag could simply be ignored, but as speeds increased the rotary was putting more and more power into spinning the engine, and less into spinning the propeller.

One clever attempt to rescue the design was made by Siemens AG. The crankcase and cylinders spun counterclockwise at 900 RPM while the crankshaft spun clockwise at the same speed. This was achieved by the use of bevel gearing at the rear of the crankcase, resulting in the Siemens-Halske Sh.III, running at 1800 RPM with little net torque. It was also apparently the only rotary engine to use a regular style of throttleable carburetor, just as in an in-line engine. Used on the Siemens-Schuckert D.IV fighter, the new engine created what is considered by many to be the best aircraft of the war.

By the end of the war only a single new rotary powered aircraft was designed, Fokker's own D.VIII, designed solely to provide some use for their Oberursel factory's backlog of now-useless Ur.II 110 hp engines, themselves clones of the Le Rhône 9J rotary. When the war ended, the rotary disappeared almost instantly, with WWI engines being used for training for a short time until their poor fuel economy drove the users to newer engines.


Use in cars and motorcycles

Although the rotary engines were mostly used in aircraft, there were also a few cars and motorcycles with rotary engines. The most famous motorcycle (probably because of winning many races) is the Megola motorcycle with a radial rotary engine inside the front wheel. Another motorcycle with a radial rotary engine was the Redrup Radial, which had a rotating 3 cylinder engine in its frame.

In 1904, the Barry engine was built in Wales, a rotating 2 cylinder boxer engine inside a motorcycle frame, weighing 6.5 kg. In the 1940s Cyril Pullin developed the Powerwheel, a wheel with rotating one cylinder engine, clutch and drum brake inside the hub but it never went into serial production.

Cars with rotary engines were built (among others) by American companies Adams-Farwell, Bailey, Balzer and Intrepid.


Other Rotary Engines

Besides the configuration described in this article with cylinders moving around a fixed crankshaft, several other very different engine designs can also be described as rotary engines. The most notable of these, the Wankel rotary engine has also been used in cars (notably by Mazda, such as in the RX-7 and RX-8), as well as in some experimental aviation applications.

Square engine

The square engine is an engine configuration used on some 4-cylinder motorcycles like the Ariel Square Four. It's easiest to think of a square-four engine as a pair of straight-twin (AKA parallel-twin) engines with their crankshafts mated together using gears to give a common output.

This design was revived as a two-stroke version on some racing Suzukis, and their subsequent road-going version the Suzuki RG500. Although some racing success was achieved, the road bikes didn't sell in great numbers, and the design was phased out in favour of in-line, four-stroke designs, as at the time two stroke engines were quickly being superseded by more economical and reliable four strokes.

The engine is only referred to as "square" when four cylinders are utilised, otherwise the engine is a U engine.

An engine can also be referred to as "square" when the bore and stroke are exactly equal.

U engine

A U engine is a piston engine made up of two separate straight engines (complete with separate crankshafts) joined by gears or chains. The design is also sometimes described as a "twin bank" or "double bank" engine, although these terms are sometimes used also to describe V engines.

This configuration is uncommon as it is heavier than a V design. The main interest in this design is its ability to share common parts with straight engines. However, V engines with offset banks can also share straight engine parts (except for the crankshaft), and this is therefore a far more common design today when both engine forms are produced from the same basic design.

An engine of this type was the 16-cylinder engine found on the Bugatti Type 45, and only two were produced. However, Bugatti licensed the design to Duesenberg in America, who produced about 40, and Breguet of France, who both intended the engine for aircraft use.

Matra developed a high-end Bagheera prototype powered by a 2.6 L U8 engine made of two Simca 1000 Rallye 2 Straight-4s connected by chains around 1974. However with petroleum crisis this car was never put in production.

Several types of U-form diesel engine have been historically produced, by companies such as Lister Blackstone and Sulzer Brothers Ltd. A twin bank diesel engine for marine use is described in US Patent 4167857 . However, no further documentation has been found for any ship or marine application of such an engine.

Sulzer Brothers developed a diesel engine for rail traction of this type, the LD series, in the 1930s, that was in production for more than fifty years. Several cylinder sizes were produced, including the 19 (bore 190 mm), 22 (bore 220 mm), 25 (bore 250 mm), 28 (bore 280 mm) and 31 (bore 310 mm). The engines of the LD and later, the LDA series, were commonly found in 6 and 8 cylinders inline and 12 cylinders U form. The U form engines were installed in railway locomotives operating in several countries, including Britain, Bulgaria, China, France, Poland and Romania. Sulzer Brothers later discontinued the rail traction engine business.

Naturally-aspirated engine

A naturally-aspirated engine or normally-aspirated engine (or "NA" - aspiration meaning breathing) refers to an internal combustion engine (normally petrol or diesel powered) that is neither turbocharged nor supercharged. Most automobile gasoline (petrol) engines are naturally-aspirated, though turbochargers and superchargers have enjoyed periods of success, particularly in the late 1980s and the current 2000s era. However, most road-going diesel-engined vehicles use turbochargers, because naturally-aspirated diesels generally cannot offer suitable power:weight ratios to be acceptable in the modern car market.

Air or fuel-air mixture is forced into the cylinders by natural atmospheric pressure upon opening of the inlet valve or valves. The pressure within the cylinder is lowered by the action of the piston moving away from the valves (so as to expand the volume available for incoming air). In some cases the lowering of the cylinder pressure is enhanced by a combination of the speed of the exhaust gases leaving the cylinder and the closing of the exhaust valve at the appropriate time. A tuned exhaust can help with this but generally only works at a narrow range of engine speeds and hence is most useful in very high performance cars, aircraft and helicopters. Many NA engines today make use of Variable Length Intake Manifolds to harness Helmholtz resonance, which has a mild forced induction effect but is not be considered true forced induction. Cylinder head porting design is of premium importance in naturally aspirated engines. Camshafts usually will be more "aggressive", having greater lift and duration. Also, cylinder head gaskets will be thinner, and with the top of the piston rising up into the combustion chamber, for high-performance NA engines that benefit from higher compression.

Natural aspiration gives less power than either turbo or supercharged engines of same engine displacement and development level but is cheaper to produce and generally operates with better fuel efficiency. In drag racing, naturally-aspirated vehicles are vehicles that do not run a blower, a turbo, nor use nitrous oxide.

Many racing series specify NA engines to limit power and speed. NASCAR, Indycar, and Formula One are all in this category. Naturally-aspirated engines have been mandated in Formula One since 1989, in order to curb the excessive powers being developed by engines with superchargers or turbochargers.

Active Fuel Management

Active Fuel Management (formerly known as Displacement on Demand) is a trademarked name for the automobile variable displacement technology from General Motors. It allows a V6 or V8 engine to "turn off" half of the cylinders under light-load conditions to improve fuel economy. EPA tests show a 6% to 8% improvement in fuel economy, but real-world highway use promises even larger gains.

GM's current Active Fuel Management technology uses a solenoid to deactivate the lifters on selected cylinders of a pushrod V-layout engine.


Background

In the U.S., high-powered multi-cylinder internal combustion engines are perceived to be necessary to satisfy driver demands for quick acceleration, oversized vehicles and/or heavy towing capacity, but during daily use they are generally operated at power settings of less than 25%. For example, at freeway speeds, less than 40 hp (30 kW) are required to overcome aerodynamic drag, rolling friction, and to operate accessories such as air conditioning. Thus, a high-powered, large-displacement engine is highly inefficient and wasteful when being used for normal driving conditions- the vast majority of the time.

In general a Naturally-aspirated engine provides maximum power when the engine throttle is held wide open. When less power is needed, the throttle is mostly closed. As such the engine has to work to simply draw air through the throttle. The work that's done is called a "pumping loss". If some of the cylinders could be switched off, however, less air would be required, and the throttle held further open, thereby reducing pumping losses and increasing overall engine thermal efficiency. This is the motivation for cylinder deactivation.

In order to deactivate a cylinder, the exhaust valve is prevented from opening after the power stroke and the exhaust gas charge is retained in the cylinder and compressed during the exhaust stroke. Following the exhaust stroke, the intake valve is prevented from opening. The exhaust gas in the cylinder is expanded and compressed over and over again and acts like a gas spring. As multiple cylinders are shut off at a time (cylinders 1, 4, 6 and 7 for a V8), the power required for compression of the exhaust gas in one cylinder is countered by the decompression of retained exhaust gas in another. When more power is called for, the exhaust valve is reactivated and the old exhaust gas expelled during the exhaust stroke. The intake valve is likewise reactivated and normal engine operation is resumed. The net effect of cylinder deactivation is an improvement in fuel economy and likewise a reduction in exhaust emissions. General Motors was the first to modify existing, production engines to enable cylinder deactivation.


Second generation

The electronics side was improved greatly with the introductions of Electronic Throttle Control, electronically controlled transmissions, transient engine and transmission controls, engine emissions controls, and vastly increased computing power. A solenoid control valve assembly integrated into the engine valley cover contains solenoid valves that provide a pressurized oil signal to specially designed hydraulic roller lifters provided by Eaton Corp. and Delphi. These lifters disable and re-enable exhaust and intake valve operation to deactivate and reactivate engine cylinders. Unlike the first generation system, only half of the cylinders can be deactivated. It is notable that the second generation system uses engine oil to hydraulically modulate engine valve function. As a result, the system is dependent upon the quality of the oil in the engine. As anti-foaming agents in engine oil are depleted, air may become entrained or dissolve in the oil, delaying the timing of hydraulic control signals. Similarly engine oil viscosity and cleanliness is a factor. Use of the incorrect oil type, i.e. SAE 20W40 instead of SAE 5W20, or the failure to change engine oil at factory recommended intervals can also significantly impair system performance.

In 2001, GM showcased the 2002 Cadillac Cien concept car, which featured Northstar XV12 engine with Displacement on Demand. Later that year, GM debuted Opel Signum² concept car in Frankfurt Auto Show, which uses the global XV8 engine with displacement on demand. In 2003, GM unveiled the Cadillac Sixteen concept car at the Detroit Opera House, which featured an XV16 concept engine that can switch between 4, 8, and 16 cylinders.

On April 8, 2003, General Motors announced this technology (now called Active Fuel Management) to be commercially available on 2005 GMC Envoy XL, Envoy XUV and Chevrolet TrailBlazer EXT using optional Vortec 5300 V8 engine. GM also planned to extend the technology on new High Value LZ8 V6 engine in some 2006 mid-size passenger cars. In both designs, half of the cylinders can be switched off under light loads.

Active Cylinder Control

DaimlerChrysler's Active Cylinder Control (ACC) is a variable displacement technology. It debuted in 2001 on the 5.8 L V12 in the CL600 and S600. Like Chrysler's later Multi-Displacement System, General Motors' Displacement on Demand and Honda's Variable Cylinder Management, it deactivates one bank of the engine's cylinders when the throttle is closed.

In order to preserve the sound of the engines, DaimlerChrysler worked with Eberspaecher to design a special exhaust system for ACC-equipped vehicles. The system uses an active valve to divert exhaust between two different exhaust systems. It also has a variable length intake manifold system to optimize output in the two modes.

Variable Cylinder Management

Variable Cylinder Management (VCM) is Honda's term for a variable displacement technology. It uses the i-VTEC system to disable one bank of cylinders during specific driving conditions (for example, highway driving) to save fuel. Unlike Chrysler and General Motors' pushrod systems, Honda's VCM uses overhead cams.

It uses a solenoid to unlock the cam followers on one bank from their respective rockers, so the cam follower floats freely while the valve springs keep the valves closed. The engine's drive by wire throttle allows the engine management computer to smooth out the engine's power delivery, making the system imperceptible. Vehicles equipped with VCM are equipped with an "ECO" indicator on the dashboard which corresponds to the VCM system's operation. Vehicles equipped with VCM also include Active Noise Cancellation (ANC) and Honda's Active Control Engine Mount (ACM) system. The ANC and ACM systems work in cooperation to cancel both noise and vibration that could occur in relation to the cylinder deactivation process.


Vehicles equipped with VCM:

* 2006 Honda Accord Hybrid (J30)
* 2006 Honda Odyssey (J35)
* 2006 Honda Pilot (J35)

Variable displacement

Variable displacement is an automobile engine technology that allows the engine displacement to change for improved fuel economy. Many automobile manufacturers have adopted this technology as of 2005, but it is not a new concept.

Most variable displacement systems work by turning off a bank of cylinders in a V engine, but the initial systems worked differently. Pioneered on Cadillac's ill-fated L62 "V8-6-4" engine, the original multi-displacement system turned off opposite pairs of cylinders, allowing the engine to have three different configurations and displacements. But the system was troublesome, and the technology was quickly retired.

No automaker attempted the same trick again until Mercedes-Benz experimented with their Multi-Displacement System V12 in the 1990s. It was not widely deployed until the 2004 DaimlerChrysler Hemi. Other systems appeared in 2005 from GM (Active Fuel Management in the Generation IV small-block) and Honda (Variable Cylinder Management on the J family engines). Honda's system works by deactivating a bank of cylinders, while the Chrysler Hemi shuts off opposing pairs.

Two issues to overcome with all of these systems is the unbalanced cooling and vibration of variable-displacement engines.

Hemi engine

Hemi (from "hemisphere") or "crossflow cylinder head" is a design of internal-combustion engines in which the cylinder head's combustion chamber is of hemispherical form. The term, "Hemi engine" is a trademark of Chrysler Corporation, though the concept is used by many manufacturers.

The BMW double push rod design, taken over by Bristol Cars, the Peugeot 403 and the Toyota T engine are other well known examples. Harry Arminius Miller racing engines were a more notable example. Stutz had built four valve engines, resembling modern car engines. Chrysler became synonymous with the "Hemi" by building them in such large numbers.

The hemispherical combustion chamber design puts the intake/exhaust valves in-line, rather than side-by-side, allowing for better flow of air through the head (although the inlet and exhaust valves are not simultaneously open and there is no continuous flow). The spark plug in the center of the chamber makes for better ignition of the fuel/air mixture. These aspects help make the hemi-type engine more efficient and powerful, and less prone to engine knock.

The hemispherical cylinder head increases the engine's efficiency through reduced thermal energy loss and increased airflow through the engine. (A hemisphere has the lowest surface area to volume ratio, meaning the most space for combustion while losing the least amount of energy to the engine walls.) Drawbacks such as increased production cost have meant that it has been a rare design. Placing the intake on the opposite side of the engine also reduces the air intake temperature and increases efficiency.

Hemispherical cylinder heads have been used in some engines since they were first used by the Belgian car maker Pipe in 1905. Most applications have been in higher-priced luxury or sporting vehicles, because the hemi design is more expensive to build.

Perhaps the best-known proponent of the Hemi design has been the Chrysler Corporation, which has produced three generations of such engines: the first (the Chrysler FirePower engine) in the 1950s; the second (the 426 Hemi) from the mid 1960s through the mid 1970s; and finally in the early 2000s. Chrysler has used the word "Hemi" extensively in its advertising, to the extent that the word is indelibly associated with Chrysler in North America.

Porsche has also been a notable user of the Hemi design, generating up to 86 hp per liter displacement on production cars (1973 2.4 L 911S), and even more on racing engines (906 Carrera engine). Jaguar used this head design as well on the legendary XK engines, which powered cars ranging from the Le Mans winning D-Type to the XJ6 sedan.

Other manufacturers used the hemispherical design before World War II, including Daimler and Riley.




Chrysler Hemi engines

Chrysler's first experience with the Hemi design was during World War 2, in which it developed an experimental 2500 hp (1864 kW) Chrysler IV-2220 V16 engine for the P-47 Thunderbolt. Experience with this engine led to Chrysler using the Hemi design for their first overhead valve V8 in 1951. This design, the Chrysler FirePower engine, was used until 1959.

In 1964, Chrysler introduced a new 426 in³ (7.0 L) Hemi, designed to win at NASCAR racing and sold to the public to meet homologation requirements and to enable the public to buy the winning engine. It was based on the Chrysler RB engine big-block. The engine was available through 1971, and the DaimlerChrysler corporation still sells crate engines and parts. It was available in most Mopar muscle cars and pony cars of the period, although its high price, limited street tractability and poor gas mileage kept sales fairly low. Hemi blocks were traditionally painted orange to distinguish them from other V8s. The Hemi head design is so efficient and effective that it was, and is, a top performer in NHRA, IHRA, UDRA and other sanctioned drag racing events throughout the world. Racers like "Big Daddy" Don Garlits have set world records using Hemi power.

Chrysler introduced a modern Hemi in 2002. This engine is not a true hemispherical head engine; it has a polyspherical combustion chamber, but retains the Hemi's traditional inline perpendicular valves. This engine replaced Chrysler's large LA family of engines, particularly the Magnum 5.9, in the early 2000s. It is available in two sizes; 5.7 and 6.1 liters. Some versions of the 5.7L, including most 2006 production units, utilize a variable displacement technology called the Multi-Displacement System (MDS) to improve fuel economy. Also, at the 2005 SEMA show, Chrysler unvieled a 505-horsepower 6.4L Hemi which will be available as a crate engine and might find its way into production, perhaps with reduced horsepower.

Gnome Monosoupape

The Monosoupape, French for single-valve, was a particular engine design used by Gnome et Rhône's later rotary engines. It used a clever arrangement of internal ports and a single valve to replace a large number of parts normally found on a conventional arrangement, and made the Monosoupape engines some of the most reliable of the era.

Earlier Gnome (as opposed to Le Rhône) designs used a unique arrangement of valves in order to avoid needing pushrods and other complex devices to operate the engine cycle. Instead a single exhaust valve on the cylinder head was operated by a counterweight that opened the valve when the pressure dropped at the end of the power stroke. The intake valve was operated similarly, but placed right in the middle of the piston head, where it opened to allow the charge to enter through a hollow crank from the center of the engine. Although clever, the system had several drawbacks. One was that maintaining the intake valve, which could easily become jammed, required the cylinder heads to be removed. Another was that in order to get the timing and pressures right for the rod-less operation, the valves opened at times that were not all that efficient; the Gnome's had even poorer fuel economy than other rotaries, which were bad enough.

Beginning with the power stroke, the four-stroke engine operated normally until the piston was just about to reach the bottom of its stroke (bottom dead center, or BDC), when the exhaust valve was opened "early". This let the still-hot fuel "pop" out of the engine while the piston was still moving down, relieving exhaust pressure and preventing exhaust gases from entering the crankcase. After a small additional amount of travel, the piston uncovered 36 small ports around the base of the cylinder, leading to the crankcase which held additional fuel/air mixture (the charge). No transfer took place at this point since there was no pressure differential, the cylinder was still open to the air and thus at ambient pressure. The overhead valve exhausted directly into the slipstream since there was no exhaust manifold in order to save weight.

The piston completed its exhaust stroke until top dead center (TDC) was reached, but the valve did not close. By being open to the slipstream, total scavenging occurred as the air moving past the cylinder created a partial vacuum inside. The piston began to move down on its intake stroke with the valve still open, pulling fresh (presumably un-filtered) air into the cylinder. It remained open until it was two-thirds of the way down, at which point the valve closed and the remainder of the intake stroke caused a partial vacuum to form in the cylinder. When the piston uncovered the transfer ports it sucked the balance of the charge as a result of the partial vacuum in the cylinder and the atmospheric pressure in the crankcase.

The charge was an overly rich mixture of fuel and air, which was acquired through the hollow crankshaft, and fuel that was continuously injected by a fuel nozzle on the end of a fuel line, entering the crankcase through the hollow crankshaft. The nozzle was in the proximity of, and aimed at, the inside base of the cylinder where the transfer ports were located. The fuel nozzle was stationary with the crankshaft, and the cylinders rotated into position in turn. The compression stroke was conventional.

The spark plug was installed horizontally into the rear of the cylinder at the top but had no connecting high-voltage wire. An internal-tooth ring gear mounted on the engine drove a stationary magneto mounted to the firewall, whose high-voltage output terminal passed in close proximity by the spark plug terminals. This arrangement eliminated the need for points, distributor, high-voltage wiring and capacitors. This ring gear also drove the oil pump, which supplied oil to all bearings, and through hollow push rods to the rockers and valves. This ring gear also drove the air pump that pressurized the fuel tank as an early form of fuel injection. There was no carburetor, saving more weight.

With no carburetor or throttle, and constant fuel pressure, there were only two power settings: full throttle or none; the engine did not even have the ability to idle. Like most rotaries, the Monosoupape's were equipped with a "blip switch" that could cut the ignition. This had to be used sparingly, as the engine would continue to pull fuel into the crank and cylinders, so turning the ignition back on after too long a period could cause the engine to explode.

Because the entire engine rotated, it had to be precisely balanced. So castings and forgings could not be used, instead, precision machining of all parts was made necessary. As a result, Monosoupapes were extremely expensive to build, the 100 hp models costing $4,000 in 1916, about $65,000 in year 2000 dollars.


Motorcycle use

From 1921 to 1924, the German Megola motorcycle was produced that featured a monosoupape rotary engine mounted within the front wheel.

Radial engine

The radial engine is a configuration of internal combustion engine, in which the cylinders are arranged pointing out from a central crankshaft like the spokes on a wheel. This configuration was formerly very commonly used in aircraft engines before being superseded by turboshaft and turbojet engines.

The cylinders are connected to the crankshaft with a master-and-articulating-rod assembly. One cylinder has a master rod with a direct attachment to the crankshaft. The remaining cylinders' connecting rods have pinned attachments to rings around the edge of the master rod . Four-stroke radials almost always have an odd number of cylinders, so that a consistent every-other-piston firing order can be maintained, providing smooth running.

For aircraft use the radial has several advantages over the inline design. With all of the cylinders at the front of the engine (in effect), it is easy to cool them with airflow. Inlines require a cooling fluid to remove heat or complicated baffles to route cooling air, as the rear-most cylinders receive little airflow. Air cooling saves a considerable amount of complexity, and also reduces weight to some degree.

In addition the radial is far more resistant to damage; if the block cracks on an inline that entire cylinder bank will lose power, but the same situation on a radial will often only make that individual cylinder stop working.

These sorts of advantages – light weight and reliability – suggest that the radial layout is a natural fit for aircraft uses. However the radial design also has two important disadvantages. One is that any supply of compressed air (from a turbocharger or supercharger) has to be piped around the entire engine, whereas in the inline only one or two pipes are needed, each feeding an entire cylinder bank. The other disadvantage is that the frontal area of the radial is always much larger than the same displacement inline, meaning that the radial will often have greater drag. For a low-speed plane this is not very important, but for fighter aircraft and other high-speed needs, this was initially a "killer problem," but was mitigated significantly with the introduction of the NACA cowling in the late 1920s. The large frontal area combined with the durability of radial engines proved advantageous to fighter aircraft at times though, particularly those in the attack role where the engine would act as an additional layer of armor for the pilot.

The debate about the merits of the radial vs. the inline continued throughout the 1930's, with both types seeing at least some use. The radial tended to be more popular largely due to its simplicity, and most navy air arms had dedicated themselves to the radial because of its improved reliability (very important when flying over water) and lighter weight (for carrier takeoffs).

In the mid-1930s a new generation of highly streamlined high-speed aircraft appeared, along with more powerful V-type engines like the Rolls-Royce Merlin and Daimler-Benz DB 601. This re-opened the debate anew, with the needs of streamlining often winning out. However the Focke-Wulf Fw 190 and Lavochkin La-5 showed that a radial engine fighter could compete with the best of the inlines, given a proper installation. From that point on many new designs used radials, and after the war the inlines quickly disappeared from the now-smaller aircraft market.

Originally radial engines had but one bank of cylinders, but as engine sizes increased it became necessary to add extra banks. Most did not exceed two banks, but the largest radial engine ever built in quantity, the Pratt & Whitney Wasp Major, was a 28-cylinder 4-bank radial engine used in many large aircraft designs in the post-World War II period. USSR also built a limited number of Zvezda 42-cylinder diesel boat engines featuring 7 banks of 6 cylinders each, bore of 160 mm (6.3 in), stroke of 170 mm (6.7 in), and total displacement of 143.5 liters (8,756 in³). The engine produced 4,500 kW (6,030 hp) at 2,500 rpm.

At least three companies build modern radials today. Vedeneyev engines produces the M-14P model, 360 HP radial used on Yakovlev's, and Sukhoi Su-26 and Su-29 aerobatic aircraft. The M-14P has also found great favor among builders of Experimental category aircraft, such as the Pitts S12 "Monster" and the Murphy "Moose". 110 horsepower, 7 cylinder and 150 horsepower, 9 cylinder engines are available from Australia's Rotec Engineering. Miniature radial engines for model airplane use are also available from OS of Japan and Technopower.

While the vast majority of radial engines have been produced for gasoline fuels, Nordberg Manufacturing Company of the USA developed and produced a series of large radial diesel engines from the 1940s. Designed initially for electricity production in aluminium smelters, these engines differed from the norm of radial design in having identical connecting rods in all cylinders, lacking the master/slave rod usually found. The engine design also permitted even numbers of cylinders in a single rank with the cylinders being fired in consecutive order. The engines were a two-cycle design and were also available in a dual-fuel gas/diesel model. A number of powerhouse installations utilising large numbers of these engines were made in the US.

X engine

An X engine is a piston engine comprising twinned V-block engines horizontally-opposed to each other. Thus, the cylinders are arranged in four banks, driving a common crankshaft. Viewed head-on, this would appear as an X. Since 24-cylinder models were the predominant configuration, it is most likely (but not known) that the angles between banks would have been 60-120-60-120, and not 90-90-90-90, since V-12 engines most commonly use a 60-degree bank to improve engine vibration characteristics. X-engines were often coupled engines derived from existing powerplants.

This configuration is extremely uncommon, primarily due its weight and complexity as compared to a radial engine. However, it was more compact (per number of cylinders) than a vee-engine, and possibly easier to thermo-regulate than a comparable radial engine. In practice, the X-engine inherited the drawbacks of both inline and radial designs rather than their advantages.

Most examples of X-engines are from the World War II era, and were designed for large military aircraft. The following are examples of this engine type:

* Daimler Benz DB 604, an X-24 developed for the Luftwaffe’s Bomber B program. Development suspended.
* Isotta-Fraschini Zeta R.C. 24/60, an X-24 developed for the Caproni F6 fighter, but never fully completed before Italy’s surrender in 1943.
* Rolls-Royce Vulture, an X-24 based on two Peregrines and the powerplant of the ill-fated Avro Manchester bomber and the Hawker Tornado fighter.

Opposed piston engine

An opposed piston engine is one in which the cylinders are double-ended, with a piston at each end and no cylinder-head. Some variations of the Opposed Piston or OP designs can use 1 crankshaft like the Doxfordship engines and the Comer OP truck engines

A more common layout uses 2 crankshafts or even 3 Crankshafts like the Napier Deltic diesel engines. These engines use three crankshafts serving three banks of double-ended cylinders arranged in an equilateral triangle, with the crankshafts at the corners. These were used in railway locomotives and to power fast patrol boats. Both types are now largely obsolete, although the Royal Navy still maintains some Deltic-powered Hunt Class Mine Countermeasure Vessels.

The first Junkers engines had but one crankshaft the upper pistons having long connecting rods outside the cylinder. These engine were the forrunner of the Doxford marine engine. There is currently a resurgence of this design in a boxer configuration Later Junkers engines like the Junkers Jumo 205 diesel aircraft engine, use two crankshafts, one at either end of a single bank of cylinders. There is also an effort to reintroduce the OP diesel aircraft engine

This configuration has also been used for marine auxiliary generators and for larger marine propulsion engines, notably Fairbanks-Morse diesel engines used in both conventional and nuclear US submarines. Fairbanks-Morse also used it in diesel locomotives starting in 1944. With the addition of a supercharger or turbocharger, opposed piston designs can make very efficient two-stroke cycle Diesel engines. Some attempts were made to build non-diesel 4-stroke engines, but as there is no cylinder head, the bad location of the valves and the spark plug makes them inefficient.

Both the Jumo and Deltic engines used one piston per cylinder to expose an intake port, and the other to expose an exhaust port. Each piston is referred to as either an intake piston or an exhaust piston depending on its function in this regard. This layout gives superior scavenging, as gas flow through the cylinder is axial rather than radial, and simplifies design of the piston crowns. In the Jumo 205 and its variants, the upper crankshaft serves the exhaust pistons, and the lower crankshaft the intake pistons. In designs using multiple cylinder banks, such as the Junkers Jumo 223 and the Deltic, each big end bearing serves one inlet and one exhaust piston, using a forked connecting rod for the exhaust piston.

The Doxford Engine Works of the UK designed and built very large opposed-piston engines for marine use. These engines differ in design from Jumo and Fairbanks-Morse engines by having external connecting rods outside the cylinder linking the upper and lower pistons, thus requiring only a single crankshaft. The first engine of this type was developed by Karl Otto Keller in 1912. Doxford obtained a sole UK license from Oechelhauser and Junkers to build this design of engine. After World War 1, these engines were produced in a number of models, such as the P and J series, with outputs as high as 20000 hp. Certain models were license-built in the US. Production of Doxford engines in the UK ceased in 1980.

VR6 engine

The VR6 engine is a configuration developed by the Volkswagen Group. It is similar to the V engine, but with the cylinders offset from each other and tilted by 10.6° or 15° instead of the more common 45°, 60°, or 90°.


Description

The name VR6 comes from a combination of V engine (German: V-Motor) and the German word Reihenmotor (straight engine). The combination of the two can be roughly translated as "inline V6 engine".

The VR6 was specifically designed for transverse installation in front wheel drive vehicles. By using the narrow 15° VR6 engine, it was possible to install a six-cylinder engine in existing Volkswagen models. A wider V6 engine of conventional design would have required lengthening existing vehicles to provide enough crumple zone between the front of the vehicle and the engine, and between the engine and the passenger cell. In addition, the VR6 is able to use the firing interval of an Inline-6 engine. As a result, it is nearly as smooth as an Inline-6.

The narrow angle between cylinder banks also allows just two camshafts to drive all of the valves, and a single cylinder head to be used. This simplifies engine construction and reduces costs. In early (12 valve) VR6 engines, one camshaft is used per bank of cylinders. This is most similar to the operation of a SOHC V6 engine. However, later (24 valve) VR6 engines use one camshaft for all intake valves and one camshaft for all exhaust valves. This is most similar to a DOHC Inline-6 engine.

There are several different variants of the VR6 engine. The original VR6 engine displaced 2.8 L and featured a 12 valve design. These engines produced 174 PS (172 hp/128 kW) and 240 N•m (177 ft•lbf) of torque.


History

The VR6 engine was introduced in Europe in 1991 in the Passat and Corrado, and in North America the following year. The Passat, Passat Variant wagon and US-spec Corrado used the original 2.8 L design, while the Euro-spec Corrado and the 4WD Passat Syncro received a 2.9 L version with 190 PS (187 hp/140 kW). This version also had a free flowing 6 cm (2.5 in) catalytic converter, enlarged inlet manifold and larger throttle body.

The 2.9L engine, as destined for the Corrado, was originally designed to benefit from a dual tract variable-length inlet manifold called the VSR (German: "Variables SaugrohR") and made by Pieronberg for VW Motorsport. This gave extra low-down torque but was deleted before production on cost grounds and was instead offered as an aftermarket option. The design was later sold to Schrick who redesigned it and offered it as the Schrick VGI ("Variable Geometry Intake").

In 1992, with the introduction of the Golf's third generation, a six-cylinder engine was available for the first time in a lower-midsize segment hatchback in Europe. North America only received this engine in 1992 with the CorradoSLC ,1994 in the Jetta, and in 1995 in the Golf GTI... at the same time the European model started to use the 2.9 L in the VR6 Syncro model. The corresponding Vento/Jetta VR6 versions appeared in the same years.

In 1997, VW removed a cylinder from the VR6, creating the VR5, the first block to use an uneven number of cylinders in a V design (other than the Honda V3 triples of MotoGP fame). This version, which had a 2.3 L capacity, was capable of 150 PS (148 hp/110 kW) and had a maximum torque of 209 N•m (154 ft•lbf). It was introduced in the Passat in 1997, and later in the Golf and Bora in 1999.

For 1999, VW added further modifications to the design, with the introduction of the 24-valve 2.8 L VR6. This engine produced 204 PS (201 hp/150 kW) and 265 N•m (195 ft•lbf) of torque. The new version was not available in the Passat (as it was incompatible with the then-current generation's longitudinal layout), but was introduced as the range topper in the Golf and Bora. The VR6 name was dropped as a commercial designation, and the 4WD system (4Motion) was now standard on the V6 in Europe. The corresponding multivalve V5 was only released in 2001, with a 20 PS power increase, to 170 PS (168 hp/125 kW). The multivalve V6 was only introduced in North America in 2002 (where it retained the VR6 name).

In 2003, a high performance 3.2 L version of the engine was introduced to power VW's limited-production Golf R32 and a new range-topping variant of the Audi TT. According to Volkswagen, this variant produced 250 PS (247 hp/184 kW) and 320 N•m (236 ft•lbf) of torque in TT trim and 241 PS(238 hp/177 kW) in R32 trim. In 2004, VW imported the Golf R32 to North America using the same 3.2L VR6 as the Audi TT. Although it was rated by VW at 241 HP, the North American R32 featured a larger Mass Airflow Sensor than the European R32 (3" in diameter compared to 2.75"), and the airbox differed as well.

The 3.2 is now used as a range-topper in Audi A3 or as an entry level version in the VW Touareg and Porsche Cayenne, a