What is the main purpose of using a turbocharger or supercharger in an engine?

The primary purpose of using a turbocharger or supercharger in an engine is to increase the volumetric efficiency. This is achieved by forcing more air into the engine's combustion chamber than would be possible through natural aspiration alone. By compressing and delivering a greater volume of air, these forced induction systems enable the engine to burn more fuel, which leads to an increase in power output.

Higher volumetric efficiency means that the engine can perform better at various RPMs, improving acceleration and overall performance. By improving the engine's ability to intake air, turbochargers and superchargers enhance its power potential without necessarily needing a larger engine displacement.

This practice also relates to a more effective combustion process, as an optimized air-fuel mixture leads to better combustion efficiency. Although using a turbocharger or supercharger may have secondary effects on fuel consumption and emissions, their primary function is focused on maximizing the engine's performance via increased volumetric efficiency.