Engine Air Flow

The Engine Air Flow is not constant in time but periodic with the opening of the inlet valve. In order to measure the average air flow into the engine, the intake is coupled to a large volume tank which acts as a "capacitance" smoothing the flow at the inlet side of the tank. An electronic flow-meter is located at this inlet and is used to determine the average air flow.

The expected flow can also be estimated from the known swept volume of the cylinder and the engine RPM. The engine acts as a pump and, if the cylinder pressure remains at one atmosphere during the inlet stroke, the quantity of air per inlet stroke can be computed.