'99 9-5 hooter valve options?

What's a hooter valve ?

Graham

Turbo bypass valve. Sounds like an irate owl when it leaks.

The function of the bypass valve is to keep the turbo spinning when going off the pedal, thereby reducing turbo lag. I don't see how that can increase HP.

in article snipped-for-privacy@mid.individual.net, Dave Hinz at snipped-for-privacy@gmail.com wrote on 03/03/2007 22:30:

Unless you want a shiny one, go stock replacement, but from VW. SAAB seem to make those valves up by 100% compared to the same valve sold at VW! I assume the 9-5 2.3 will be very similar in many ways to the 9000 2.3, which I know a chap running over 1 bar about over 300 BHP with the stock valve - he reckons there's no merit in changing for an expensive shiny one.

If you're going to run up rated boost, the standard valve will hold the pressure.

Paul

Shirley, by definition, reducing lag is the same thing as increasing the power available at the point where the turbo would have been lagging?

Of course, the peak power of the engine won't go up, but that figure is pretty meaningless anyway.

Cheers,

Colin.

Strictly speaking, the hooter valve is used to vent excess pressure when you close the throttle plate. Otherwise the intake system would likely blow something off.

An alternative would be to open the wastegate and allow the exhaust flow to bypass the turbo. I don't know if that is not done because of the reason you stated above (keep the turbo spinning) or because you can't vent pressure fast enough through the relatively slow wastegate operation (vs. the fast acting hooter valve). Perhaps it's a combination of the two.