There are many ways to mod your car for it to output more power such as a better intake filter, a performance chip or a more free exhaust. A cool way to enhance your car is by using forced induction. Forced induction is the process of increasing the air input to an engine by using a type of compressor. These compressors increase density, pressure, and temperature of the air. Engines without this type of system are considered a naturally aspirated engine because it intakes air without the aid of another component. Forced induction is used in the automotive and aviation industry to increase the power of an engine and its efficiency. They are basically a double compression engine with the separate system feeding the compressed air and the engine taking that compressed air and compressing it again to detonate in the cylinders. This greatly increases the total compression ratio of the engine, this increased pressure is called boost.
Two common systems of forced induction are turbochargers and superchargers. Turbochargers are driven by the exhaust gases of the engine and superchargers are powered by the rotation of the engine.
Turbochargers rely on the volume and velocity of the exhaust gases to spin(spool) the turbine wheel which is connected to a compression wheel through the same shaft.The pressure created by the compression wheel can be regulated through release valves and electric controllers before going into the engine so that it does not reach a dangerously high compression ratio that causes the fuel mixture to prematurely detonate due to high temperatures, this is called pre-ignition or knock that can severely damage the engine. To overcome this drawback an intercooler is used to greatly decrease the chance of knock. This is done by cooling the charged air with the ambient flow of air or liquid causing the density to increase but the temperature to decrease.
The drawback of using a turbo is as the turbo benefits of using less power from the engine, the engine response is bad due to the time it takes for it to spool up. This delay is referred to as turbo lag and can be countered by an anti-lag or misfiring system that makes the engine to spit a bit of the fuel mixture into the exhaust duct before the turbocharger and is ignited by the hot ducting causing the turbo to spin when the engine is not delivering enough exhaust gases. To overcome turbo lag, it is also possible to get smaller turbochargers that spool up quickly and produce full boost pressure at lower engine RPMs but suffer at higher RPMs. Bigger turbos give better performance at higher RPMs but have a worse response. The response of turbos can give drivers a tricky challenge when driving because the increased torque can be received at a different time than desired.
Superchargers have almost no lag time and are always spinning proportionally to the engine. They are not as common because they use the torque produced by the engine to operate and results in a loss of power. There are three different types of superchargers, a roots-type supercharger uses lobes from two shafts to push air into the intake similar to a rotary engine but does not compress it. It is fed with air through the top of the casing and exits underneath, it is mounted on top of the engine. This supercharger also has the advantage of producing the same air/fuel ratio because, for each revolution in the supercharger, a fixed amount of air is pushed into the intake allowing a decent amount of power at low RPMs.
A screw-type supercharger is also like a roots-type supercharger, but instead of lobes, it has a screw-like rotor that compresses the air as it moves along the threads. Due to the complex system and its need of perfection for it to actually work well, this type of supercharger is more expensive than others but are more efficient to operate due to cooler air output but uses no engine oil.
A centrifugal-type supercharger is very similar to a turbocharger but instead of it being driven by gases it is belt driven. Having the same problem of using some torque from the engine like any other supercharger, this type is smaller and more compact. The downside of this supercharger is that it has a poor boost at lower RPMs and requires engine oil but are able to be used with an intercooler.
