Variable Induction System: Description and Operation

Resonance Control Power Diagram:

PURPOSE
Variable length air intake pipes provide clean, measured air, which is mixed with injected fuel for combustion. Because of the ability to change intake pipe length, throttle response is improved and horsepower is increased over a broader rpm range.

Resonance Control Schematic:

SYSTEM COMPONENTS
Resonance flap control unit
Changeover valve
Flap actuator
Resonance flap
Vacuum tank

Resonance Operation:

OPERATION
An electronically controlled flap subdivides the intake manifold into two symmetrical chambers. The resonance flap, located in the plenum, closes via the changeover valve creating a short pipe effect, substantially increasing power when:

^ Engine speed is less than 4,120 rpm and the throttle is wide open
^ Engine speed is greater than 6,720 rpm and throttle is wide open

If the above conditions are not met the flap remains open maintaining a long pipe condition. This long pipe condition is better suited for low- and mid-range load conditions.

To prevent repeated open and closing of the flap during constant engine speeds of either 4,120 of 6,720 rpm, a delay of the switchpoint depending on whether approaching form lower or higher engine rpm is incorporated.