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These are the inner workings of the Magnuson MP112 fifth-generation supercharger with its efficient 60-degree helix rotors. An internal bypass valve is controlled by the black vacuum motor at the rear of the case. A Magnuson development, the bypass actuator opens the bypass at light-throttle cruise conditions so no boost is generated. In this mode, the supercharger "naps" and requires less than .5 hp to drive to preserve excellent fuel economy and reduce wear. However, when it senses more than 4 inches of vacuum (not manifold vacuum), the actuator closes the bypass, boost production begins (5 to 7 pounds), and rear tires start smoking. The actuator is extremely sensitive and can toggle open or closed in less than a half second.