Variable Induction Control Valve: Description and Operation

Variable Inertia Charging System (VICS):

PURPOSE
Changes effective length of the intake runners to take advantage of different harmonic frequencies within the intake manifold at different engine speeds. This helps the engine produce more torque across a broader rpm range.

LOCATION
In intake manifold dynamic chamber.

OPERATION
At low and mid-range engine speeds, when the oscillation frequency is low, the shutter valves are closed, forcing intake air to take the longer path to the cylinders. At high speeds, oscillation frequency is much higher. The shutter valves open and intake air takes the short path through the manifold. This helps synchronize intake valve opening with the occurance of a high pressure area just behind each valve, while air inside the intake runners still has momentum and velocity toward the valves as they are opening. When an intake valve opens, high pressure air rushes into the cylinder followed by high velocity air from the intake runner, to help "pack" the cylinder with more air and fuel before the valve closes.