Dumping waste gate exhaust and other questions

[Dave Aukerman]

Seem to recall an effort by MTM(?) on an RS2 which used a seperate pipe for
the wastgate which ran all the way back.  Intercooler looked like it came
off a Powerstroke diesel.  Turbo the size of a pizza.  Ring any bells?

Dave

----- Original Message -----
From: "Jonas K." <jkarlsso at metabolex.com>
To: <quattro at audifans.com>
Sent: Thursday, November 01, 2001 5:29 PM
Subject: Re: Dumping waste gate exhaust and other questions


> > From: Grant Bessom <GBessom at Intersections.com>
> >
> > Question:
> > 1) What affect would dumping the waste gate to atmosphere instead of the
> > muffler have on performance?  I want the car to make a cool sound when I
> > shift at maw boost (ala World Rally cars).
>
> You do realize that dumping the waste gate gas into atmospere is not what
that "cool
> sound" is. That's anti-lag, basically injecting raw fuel into EM during
shifts. The fuel
> combusts from the high temp in the manifold, and the expanding gasses
keeps the turbo
> spooled.
>
> Furthermore, the waste gate is open on throttle, whenever boost is on, not
between shifts.
> So you would get a "sound" whenever the wastegate is open, which is very
often. Also it
> would more-or-less be the sound of a n/a 5 cyl running at WOT without a
downpipe
> connected, maybe a little muffled.
>
> Performance-wise routing the wastegate gasses through it's own exhaust
(including muffler)
> will be "best". Corky Bell mentions that the turbulence caused by
wastegate gasses coming
> into the exhaust pipe after the turbo has detrimental effects on the flow
of exhaust. But
> since all the exhaust needs to go through the catalytic converter, and
also preferably
> exposed to an O2 sensor, I'd keep it routed into the main pipe like Audi
did it from the
> factory.
>
> HTH
> Jonas
> 90 CQ
>