Perspectives on Applications of Variable Valve Timing

While Variable Valve Timing (VVT) holds the potential to alleviate some of the compromises normally associated with engine operation over broad speed and load ranges, generalizing its benefits in a quantitative manner is difficult. Details of base engine design and the means of VVT execution and engine duty cycle play major roles in determining the outcome of such an application.

With the profusion of VVT means available, the matter of selecting an appropriate system for a given engine and duty cycle is difficult particularly when there is a host of competing features and technologies.

This treatment of VVT is based on assessments of compromises associated with static valve timing and provides a framework for considering VVT as an engine performance option. Extensive use is made of pressure and geometric data, and several generalizations are made relative to strategies for incorporating common VVT systems.