What is the primary function of a turbocharger in an engine?

The primary function of a turbocharger in an engine is to increase the engine's intake air pressure using exhaust gas. A turbocharger operates by utilizing the energy from the engine's exhaust gases to spin a turbine. This turbine is connected to a compressor, which compresses the incoming air before it enters the engine's combustion chamber.

By compressing the air, the turbocharger allows more air (and consequently more oxygen) to enter the combustion chamber. This enables the engine to burn more fuel, resulting in increased power output without the need for a larger engine displacement. Essentially, the turbocharger enhances the engine's efficiency by improving its performance under a variety of operating conditions, particularly at higher altitudes where the atmospheric pressure is lower.

The other choices do not accurately describe the function of a turbocharger. Decreasing intake air pressure is contrary to its purpose, and a turbocharger does not mechanically drive the compressor in the way that an engine directly powers components. While it can improve fuel economy indirectly through enhanced performance, this is not its primary function. The primary role is indeed to increase air pressure to optimize combustion and power generation.