Date: 05 Nov 2002 16:07:57 GMT
From: Gary Fritz <>
Subject: Re: What oil for 9-5 Aero? (quadrun1) wrote: > As for the Hyperboost valve, basically, it seals much better than the > stock Bosch piece, and it responds much more quickly and definitively. > During shifts, after you lift/close the throttle, the bypass valve > immediately allows the turbo to "bypass", so that any boost before the > throttle plate is recirculated, preventing a shockwave from forming, > which would otherwise cause the turbo to stalling. I've noticed my 9-5 Aero keeps racing after I lift my foot from the throttle, and seems to take a long time to spin down to a lower RPM. Is this also due to the bypass valve? > The original Bosch piece does the same thing, but it's much slower to > react, and is prone to failure due to its flimsy diaphragm design. > I've had two failures of the original Bosch bypass valve on my old > 9000T. The diaphragm rips easily. > The Hyperboost valve is not designed to increase your overall boost > pressure, it just allows boost to build more quickly, to the levels > specified in the car's Trionic engine management system. So it's not really exceeding any specs in the engine, that's good. And it sounds like the Bosch part can actualy cause shockwaves which can damage the turbo, so these aftermarket parts are actually BETTER for the engine? I think I have something new for my Christmas list... :-) Gary

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