CamshaftA shaft in the engine on which are the lobes (cams) that operate the valves. The camshaft is driven by the crankshaft, via a belt, chain or gears, at one half the crankshaft speed. One or more camshafts regulate the opening and closing of the valves in all piston engines. Boosted engines may benefit from a different camshaft to the stock camshaft, especially if the original engine was naturally aspirated. Typically boosted engines have lower lift and less duration than their n/a versions.

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Charge coolerAn intercooler cools the intaken air by transferring the heat to the air. A chargecooler cools the intaken air by transferring the heat to water and uses a radiator to then transfer this to the air. Water can absorb heat quicker and more efficiently, so it cools the air quicker and cooler, and since colder air is denser, more air is going into the engine, thus being able to burn more fuel, increasing power. It is smaller than a regular (front mounted) intercooler and quite efficient.

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Cold Air Intake (CAI)Cold Air Intake system is a device used to bring cold air into the car combustion engine to increase power and efficiency

Downpipe (DP)The downpipe is a pipe that bolts to the back of the turbine housing of a turbocharger and begins the exit of the exhaust gas out of the car. When you look for down pipes you will typically run into 4 kinds. 1. Blank plate: Identical to stock construction with the wastegate portion completely covered. 2. Bellmouth: Completely open design. 3. Split bellmouth: Similar to bellmouth only with a divider inserted to separate the wastegate. 4. Divorced or Twin Dump: Separate exhaust and wastegate piping that connect further downstream.

DynosheetsA dynosheet is the graphical representation of the relation between engine speed and power or torque. Sometimes it shows speed on the horizontal axle rather than engine speed. The power (in BHP ,PS or wheel HP) or torque (LbsFt or Nm) is usually measured at the powered wheel or powered wheel axle(s), and usually in the gear that is closest to a 1:1 gear ratio. Some dynosheet do not show the actual measured data, but use a conversion to plot the graph, either to correct for atmospheric changes (DIN or SAE smoothing are typically used) and/or to correct to show crankshaft power (BHP) rather than (measured) wheel horse power. It depends on many variables how to determine the power loss from crank to wheel; but many tuners use 15% and many will disagree with this figure. We consider it best to show actually measured data with DIN or SAE smoothing.

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Engine Control Unit (After market ECU), EFI and piggyback systemsThe brain (ECU) of the car is responsible for pretty much everything electronic in the car, so also for making the engine run. In some cases, tuners choose to use an aftermarket kit to control parts of the engine and drive system, in order to better manage the extra power gained from a tune. Sometimes the aftermarket ECU completely replaces engine management, and sometimes it only corrects signals going to various parts of the engine , such as the MAF sensor signals, fuel pump or ignition (piggy back system). Piggy-back fuel controllers are popular because they allow users to modify stock fuel injection without replacing the entire ECU. They operate in various ways. Some of them modify the injector duty cycle control signals as they travel from the ECU to the injectors. Others modify input data to the ECU (like MAF for example), effectively “tricking” the ECU into delivering more or less fuel at a given RPM. Using flex fuel in many cases also demands aftermarket ECUs.

(Flex) Fuel, LPG and E85E85 fuel is fuel consisting of roughly 85% ethanol and 15% petrol. The petrol is used to prevent cold start issues. Using E85 may require extra modifications to the fuel system: the fuel pump must be able to handle it, ethanol clean out the system of dirt and rust, clodding up the fuel filter. E85 also needs a very different fuel/air mix to ignite, so the injection system must be altered accordingly. Due to the limited availability of E85, it makes sense to equiped the engine with a fuel management system that copes with both E85 and petrol, so called flex fuel systems. Typically this requires after market EFI systems.

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Fuel InjectorsFuel injectors spray fuel under pressure into the port (port injection) or into the cylinder (direct injection).

Intercooler (IC, FMIC)An intercooler is just another name for a heat exchanger that is used to cool air that has been compressed by either a supercharger or a turbocharger. ITis placed somewhere in the path of air that flows from the turbo or supercharger to the engine. An intercooler is needed because of the physics of air described in the Ideal Gas Law, that is PV=nRT. When the intercooler sits in front of the car, to benefit from wind from driving the car to vent the absorbed heat, we call it an FMIC: front mounted intercooler.

Explaining the ideal gas law as basic as we can, we can say that because pressure and temperature are directly proportional, as you create more pressure with your turbo or supercharger, you produce more heat as well. Hot air is less dense and therefore contains less molecules of oxygen per unit volume. This means less air for the motor in a given stroke and therefore less power produced. Hot air also causes a higher cylinder temperature and therefore can aid in pre-detonation of the combustion cycle causing detonation.

Internals (ported heads, pistons, rods, gaskets, crankshafts, etc)More oxygen in a car, combined with extra heat from burning more oxygen may trigger pre-ignition or uncontrolled explosions in the cylinder. One of the counter measures is the reduce the Compression Ratio (CR). Where some naturally aspirated engines may have a CR of up to 12.5 : 1, boosted engines tend to lower the CR to 8.5:1 . To lower compressions various things can be done, e.g. using shorter piston rods, thinkers pistons, thicker head gaskets.

The head of an engine, where the valves and camshafts are located in many engines, may also be altered to gain flow compared to the stock engine. This will improve the volumetric efficiency of a car and reduce backpressure, basically make the engine a better airpump.

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Nitrous Oxide (NoS)Nitrous Oxide (N20, aka laughing gas) is a gas that can be added to the air via the intake manifold or in the intake piping. Even though the gas itself is not flammable, it delivers more oxygen than atmospheric air by breaking down at elevated temperatures, thus allowing the engine to burn more fuel and air. Additionally, since nitrous oxide is stored as a liquid, the evaporation of liquid nitrous oxide in the intake manifold causes a large drop in intake charge temperature. This results in a smaller, denser charge, and can reduce detonation, as well as increase power available to the engine.

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Oil catch tankAn oil catch tank is a great way to keep oil blow-by from lowering the octane rating of your fuel. The crank case pressure on boosted and even non-boosted motors will often exceed ambient air pressure outside the engine. This causes the oil vapors to leave the engine and enter the combustion chamber. These oil vapors can lower octane ratings by as much as 2 points.

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Oil coolers, pumps and turbo timerA turbo timer prevents heat soaking of the turbo charger by keeping the engine oil flowing even after shutting down the car and removing the key. Oil gets very hot from a turbochargers, because it needs to keep the turbocharger as cool as possible, while the turbocharger is heated up from 950 C exhaust gas. Some tuners also choose to install an additional oil cooler to vent this stored heat of the oil when the oil is flowing. To make sure that oil is pumped into upgraded turbochargers an additional oil pump may be fitted to reduce the risk of a failure of the oil system, potentially destroying the engine and turbocharger. An additional oil pump can be required if the turbocharger is below the oil pan and gravity wouldn't help getting the hot oil out of the turbocharger.

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SuperchargerA supercharger (also known as a blower) is an air compressor used to compress air into the cylinders of an internal combustion engine. The additional mass of oxygen-containing air that is forced into the cylinders improves the volumetric efficiency of the engine which allows the engine to burn more fuel and makes it more powerful. A supercharger can be powered mechanically by belt-, gear- or chain-drive from the engine's crankshaft. Positive displacement pumps (e.g. Eaton, Lysholm, G-lader) deliver a fixed volume of air per revolution at all speeds. Internally, there are two (sometimes three) lobes that rotate, sucking in the air and force-feeding it to the engine. A centrigual supercharger (e.g. Rotrex) looks more like the compressor house of a turbocharger. The first type does not suffer from lag at all, but at high speed they take a lot of engine power to keep delivering the needed boost.

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Theory, formulas and measurementsIf you have an article or question about the theory behind engines or forced induction in particular, this is the section to ask them. Most of us recognize the parts when we look at them, but why are the built the way they are ? The engineering behind each part is more complex than meets the eye.

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TurbochargerTurbo refers to the word Turbine; which is the wheel that is spinned by the exhaust. The exhaust rotates an axle that connects the turbine housing with the compressor housing. In the compressor house, cold air is sucked in and compressed. Typically an intercooler is placed between the compressed (charged) air and the actual intake manifold, because a turbocharger gets very hot from the exhaust. The system is more efficient and suffers less from lag if the turbine housing is close to the exhaust manifold. Sometimes more than one turbo is installed (twin turbo or quad turbo), sometimes the turbo is more efficiently using the energy from the exhaust by carefully splitting the exhaust from each cylinder to rule out backpressure (twin scroll ).

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Wastegates (External)A wastegate enables exhaust to bypass the turbine housing. This is necessary to control the boost limit; an engine is usually tuned for a specific power demand; to overrun boost, meaning giving the engine too much oxygen may reduce efficiency (air fuel ratio may become lean) and cause damage to parts. Some wastegates are part of a turbocharger, sometimes external wastegates are fitted onto an engine to have more boost control from the cockpit.

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Water/Methanol InjectionOn a simple level, it's intercooling and race gas combined. When you inject water and methanol into the intake stream, you cool the air as the liquids evaporate. When you get into the combustion chamber, it slows the flame, acting just like octane. Colder air is denser, and thus contains more oxygen per volume. This will add power to your car. The fact that some of the volume is taken by water particles is neglectable.

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