One way to improve the efficiency of a naturally aspirated engine is to force additional air into it, which allows more fuel to undergo combustion on each cycle, increasing the power output of the engine. Compressing the air entering an engine’s cylinders is known as forced induction.
A supercharger is an air compressor that is directly driven by a belt or gear connected to the engine’s crankshaft. A turbocharger is a compressor powered by a turbine which feeds off the engine’s exhaust gases. Because a turbocharger uses pressure from exhaust gases that would otherwise have been wasted, it incurs less parasitic loss than a supercharger does, making it more efficient. However, turbochargers usually experience turbo lag, in which there is a delay before the exhaust pressure gets high enough to bring the turbine up to speed. Superchargers are usually more expensive than turbochargers.