Originally posted by RedSVT:
[QUOTE]Bob your theory as to the function of bypass[blow off] valves on roots superchargers is incorrect. 
Sorry RedSVT I know I'm right about the bypass valve on roots type superchargers. This comes straight from Magnuson's (aftermarket dealer for Eaton Superchargers) :
"The best kept secret in forced induction is the little known bypass valve. This small valve, when properly installed between the supercharger and the air throttle body, allows the supercharger to become extremely efficient in terms of economy and parasitic power loss. Our M90 supercharger uses less than 1/3 of 1 HP at 60 MPH cruising. The bypass is operated by a vacuum actuator control unit that is normally closed. When vacuum is high (idle-cruising) the actuator opens the bypass valve, equalizing the vacuum pressure throughout the system. When boost is required (accelerating) the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition virtually eliminates the normal parasitic power loss of a forced induction system."
http://www.magnuson-products.com/bypass_valve.htm Bob
