Variable Induction System: Description and Operation

Intake Manifold Runner Control System:

PURPOSE
The Intake Manifold Runner Control (IMRC) system optimizes engine performance and engine torque output.

Intake Manifold Runner Control System:

OPERATION
Surge plenums are fed by a single throttle body. The large size of the plenums allows the maximum volume of air required by the engine to be available at any time. The surge tanks reduce the amount of air turbulence so that a smooth flow and even amount of air is admitted to the IMRC runners. The secondary runner contains a butterfly throttle valve plate that opens by an IMRC vacuum solenoid allowing additional air into the cylinders during periods when maximum performance (above 4000 RPM) is desired.

CONSTRUCTION
The unique air intake manifold system features the following:

^ Two surge plenums connected by a crossover tube.

^ Primary (longer length) and secondary runners (shorter length).

- The long primary runner comes from the surge plenum to the opposite side of the engine. This runner has no obstruction or throttling mechanisms.

- The short secondary runner originates from the surge tank on the same side of the engine as the cylinder. The secondary runner contains a butterfly throttle valve plate.

^ Vacuum taps for EGR valve, fuel pressure regulator, canister purge and power brake booster are provided on the surge plenum.