Technician A says that the rpm range of the engine is controlled by the point where the intake valve closes. Technician B says that closing the intake valve later in the compression stroke lowers the effective compression ratio. Who is right?
A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question

Quizplus · Accepted Answer

The rpm range of an engine is indeed influenced by the point at which the intake valve closes, as it affects the engine's volumetric efficiency at different speeds. Closing the intake valve later in the compression stroke does indeed lower the effective compression ratio because it allows some of the air-fuel mixture to escape back into the intake manifold, reducing the amount of mixture available to be compressed.

Technician a Says That the Rpm Range of the Engine