Fifth Ring

I learned more than I could ever care to use about the twin turbo system on my Audi, and was wondering if we had anyone with similar wisdom on the inner workings of our s/c systems.

1. Assuming the s/c is just a mega-fan, how quickly does it reach full pressure (at what engine RPM)?

2. Also assuming it's a fan, does it overboost at higher RPMs? My old turbos had a bypass valve that dumped pressure back into the intake. Does the s/c system have a bypass also?

3. If it has a bypass, how is that actuated? On the Audi 2.7T and 1.8t engines, the performance chips changed the actuation of the bypass valves allowing boost to go higher than the factory settings before getting dumped. Is there any reason why all C32 upgrades start with pulleys (to make the s/c pump harder) rather than changing the bypass timing (to let more boost in)? Obviously, if there is no bypass, and the engine uses all of the s/c boost, then my question is answered.

4. In addition to venting excess boost, turbos also dump boost when you lift throttle (because the turbos are pumping air that the engine is not asking for). So, even if s/c boost doesn't need a limiter, it may need venting when you get off throttle.

uownme

2. It will not overboost, pulley size will only let it spin at a certain rate allowing only the appropriate pressure.

Eurocharged Rick

superchargers are driven by pulleys, not exhaust pressure like turbos, therefore you have to change the pulley inorder to obtain more psi....you can not just change the bypass valve, recirculating valve, blow-off valve, boost controller, etc. inorder to up the boost....there is no bypass valve on the C32 that i know of...

vraa

Don't the 55 s/c's have a bypass valve in order to make throttle response more linear and have less of a 'jerk' when the s/c is engaged?