What is the primary function of a "high-lift" cam in an engine?

The primary function of a "high-lift" cam in an engine is to increase the distance the valve opens, which enhances airflow into and out of the combustion chamber. This increased lift allows the engine to breathe better at higher RPMs, enabling more air and fuel to enter during the intake stroke and allowing exhaust gases to exit more efficiently during the exhaust stroke. This can lead to improved engine performance, particularly in terms of horsepower and torque. By optimizing the airflow, a high-lift cam can significantly enhance engine output, especially in performance applications where maximum efficiency and power are desired.

The other choices touch on aspects that can be impacted by modifications to an engine, but the defining characteristic of a high-lift cam is its ability to increase valve lift, which directly contributes to improved engine performance.