Variable intake manifolds are being discussed. Technician A says an intake manifold tuning (IMT)system uses a butterfly valve to divide the plenum into two small chambers at low speeds. At high engine speeds, the butterfly valve opens to form one large plenum chamber. Technician B says the intake manifold runner control (IMRC)system changes the path of air between long and short runners or between small-diameter and large-diameter runners according to engine speed. Who is correct?
A)A only
B)B only
C)both A and B
D)neither A nor B

Question

Quizplus · Accepted Answer

Both Technician A and Technician B are correct. Technician A describes the function of an intake manifold tuning (IMT) system, which indeed uses a butterfly valve to alter the plenum chamber size based on engine speed. Technician B accurately describes the intake manifold runner control (IMRC) system, which adjusts the air path between different runner lengths or diameters to optimize engine performance at varying speeds.

Variable Intake Manifolds Are Being Discussed