Quote Originally Posted by Alucard rawg View Post
I have a few questions the bypass valves seem to be hurting the low end on the pd blowers. The dyno charts I have seen make it seem that the turbo may even be better for wheeling than the roots and that blows my mind. ( dyno charts and real world =2 different things) I get that vacuum controls that the valve but how? I would want a roots because I want off idle torque but the bypass valve seems to be killing that. what kind of boost are you seeing while crawling at low rpms and little throttle? if you disconnect and plug the vacuum line does the valve say open or closed?
I can speak somewhat to Magnuson's bypass because that's what I have. According to Mag the bypass is not supposed to close until manifold pressure is at 0 bar. Think of that as wide open throttle. For guys with manual transmissions that works because you can pick a gear and step on the pedal which opens the throttle dropping the pressure and closing the bypass. For automatic transmissions guys it's an issue because you don't pick your gear and the computer's selection is most often not good. If you don't step on it all the way you're not closing the bypass all the way. That's how the system is designed. If your foot is light on the pedal then you're not on boost.

DO NOT DISCONNECT THE BYPASS VACUUM LINE! Yes, it will put you on boost all the time like a diesel or dragster. But you won't have software calibration for that condition and I genuinely believe you'll risk leaning out. Also, the effective compression and cylinder pressures will, in my opinion, wear the motor out. The block, heads and rotating assembly are not designed for it. The superchargers and turbos we are using are designed to give you the occasional boost of power you need and then sit on the sidelines to save fuel and save wear and tear. They are ideally designed for off-the-line acceleration at wide open throttle or when towing heavy loads that you need to build momentum to get going.