bypass valve

[Peter Berrevoets]

I see your point in the potential for failure in the diaphram of this bosch
unit.

However, several performance tuners and most notably Dahlback Racing in
their gazillion HP 20V Turbo motor are using this valve. The Dahlback in
fact uses two in parallel and uses quite a bit of custom fabrication to do
so.

Perhaps there is some merit to using the Bosch valve. I know they make good
products, is it perhaps the method of deployment that is in need of
modifying rather than blaming the valve itself?

my $0.02

Peter Berrevoets
1990 200TQ
Toronto, Canada

> >-----Original Message-----
> >From: quattro-admin at audifans.com
> >[mailto:quattro-admin at audifans.com]On
> >Behalf Of Ken Keith
> >Sent: Wednesday, February 07, 2001 7:21 PM
> >To: quattro at audifans.com
> >Subject: RE: bypass valve
> >
> >
> >Of course, the stock valve is a diaphragm style, while the other two
> >nice valves are piston style.  A diaphragm style can and does
> >rupture, which causes no bypass at all, which can cause problems.
> >
> >The piston style doesn't suffer the rupture failure mode, but may
> >have it's own.
> >
> >I'm most impressed with the Forge valve.  I like to be able to
> >service my parts.
> >
> >From what I can tell, the Bosch bypass valve fails pretty often.
> >When all is said and done, I hope to have some aftermarket valves
> >on my car.  $40 or whatever for the stock one is a good start,
> >especially if you are plumbing one in for the first time.
> >That's what
> >I'm going to be doing anyway.
> >
> >Ken
> >
> >On 7 Feb 2001, at 19:10, TM wrote:
> >
> >> Rob,
> >> I beg to differ. The stock Bosch bypass valves do have a
> >tendency to
> >> fail when running higher than stock boost levels. In fact,
> >my 200q had
> >> a bypass valve failure at stock boost. Our A4's valve is bad, and
> >> needs replacement as soon as weather allows. Porsche 951s
> >go through
> >> bypass valves pretty often as well.
> >>
> >> The Bailey and Forge valves that are currently popular
> >with the A4/S4
> >> crowd apparently fix the failure problem, albeit at a fairly high
> >> cost.
> >>
> >> Now if you're talking about those blow-off valves that vent to
> >> atmosphere, like the HKS and Blitz products, I have no knowledge of
> >> them other than they cause Audi engines to run rich.
> >>
> >> Taka
> >>
> >>
> >
> >