Variable Induction Control Valve: Description and Operation

Variable Inertia Charging System:

Shutter Valves (VICS):

The shutter valve, located on the outlet of the dynamic chamber to the intake manifold, is part of the "Variable Inertia Charging System" (VICS). The shutter valve assembly consists of a vacuum diaphragm and spring, and a plate valve similar to a throttle valve. Vacuum is applied to the diaphragm through a computer operated vacuum solenoid valve.


In the intake manifold, areas of high and low pressure oscillate through the intake manifold at different harmonic frequencies, depending on the engine speed. The VICS takes advantage of this by changing the effective length of the intake manifold runners, thereby changing the frequency of the oscillations. At low and mid-range engine speeds, the shutter valves are closed, forcing the intake air to take the longer path to the cylinders. At high speeds, the valves open and the intake air can the the short path through the manifold. This helps synchronize the opening of the intake valves 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. This helps the engine produce more torque across a broader rpm range.