What is supercharger in car?

Answer 1

Superchargers are basically air compressors driven by the crankshaft of the engine. There are two basic types;

Centrifugal - Centrifugal superchargers are similar to the intake side of a turbocharger driven by a gearbox instead of the engine's exhaust. In order to keep the compressor from over-revving, they are geared to operate at their speed limits near the redline of the engine. As a result, they aren't going fast enough to produce reasonable HP gains at lower RPMs; they are very "peaky".

Roots Blower - Old-school airscrews that draw in a fixed volume of air per engine revolution. They make the engine behave like a larger displacement version of itself. At higher RPM, the efficiency of the Roots blower decreases, but at low- and mid-RPMs, where most street cars are driven on a daily basis, they are the best option for moderate HP gains.