Technician A says that valve overlap takes place as the piston completes its compression stroke. Technician B says that cylinder scavenging takes place at valve overlap. Who is correct?
A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question

Quizplus · Accepted Answer

Valve overlap occurs when both the intake and exhaust valves are open at the same time, typically at the end of the exhaust stroke and the beginning of the intake stroke, not as the piston completes its compression stroke. This overlap allows for cylinder scavenging, which is the process of expelling the remaining exhaust gases and drawing in fresh air/fuel mixture, improving engine efficiency. Therefore, Technician B is correct.

Technician a Says That Valve Overlap Takes Place as the Piston