11. One thing you will notice on the side of the supercharger is this black valve (A). It is a vacuum-operated bypass valve. Why does it need a bypass valve? This allows the supercharger to become extremely efficient in terms of economy and parasitic power loss. When vacuum is high (idle-cruising), the actuator opens the bypass valve, equalizing the vacuum pressure throughout the system. When boost is required during acceleration, the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition almost eliminates the normal parasitic power loss of a forced induction system. Pretty neat, huh?