What is meant by the term inlet valve lag?

Inlet valve lag refers to the delay in the opening of the inlet valve in an internal combustion engine relative to the position of the piston during its cycle. This lag can affect engine performance, particularly during the intake stroke, as it may limit the amount of air-fuel mixture entering the combustion chamber. Proper timing of the inlet valve is crucial for optimizing engine efficiency and power output. Excessive lag can lead to reduced performance and increased emissions.