Superchargers are also called forced induction systems. An internal combustion engine works by drawing a mixture of air and fuel (the intake charge) into its cylinders, compressing that mixture and then burning it. The more air/fuel mixture that can be crammed into the cylinders for burn, the more power the engine produces. We can increase power in three basic ways:
1) By improving the engine’s ability to draw more air and fuel into the cylinders and expel its burned exhaust gases (its volumetric efficiency, or ‘breathing’)
2) By increasing the swept volume of the cylinders (the engine’s displacement), so you can fit more air and fuel into each cylinder.
3) By applying the force the intake charge into the cylinders under high pressure, squeezing more air and fuel into the available volume. Forcing air into the engine at higher than atmospheric pressure is called supercharging. A supercharger is a mechanical air compressor that pressurizes the air going into the engine. There are several types of compressor used for car and truck engines, most commonly Roots-type, centrifugal, and Lysholm compressors; each has pros and cons, but they have the same basic function.
