[200q20v] re: stock bypass valve, TBV

[Sylvester, Mike]

If you have a blow-off valve that opens at a set pressure (e.g. 25psi)you
will not be blowing off metered air, because the "air meter" is already
max'ed out anyway.

In my previous 10v turbo I installed a hotwater heater pressure relief valve
into my intercooler that opened at 25psi.  I had to do something after a
side tank blew off the IC.  Everything worked normal unless you quickly let
off the throttle after full boost.  Then when the pressure spiked between
the turbo and throttle body the pressure valve vented anything above 25psi.
I'm sure the air metering is railed at 25psi.

Mike

-----Original Message-----
From: Glen Dustin Powell [mailto:gpowell at ennovatenetworks.com]
Sent: Thursday, September 14, 2000 9:20 AM
To: 'Brett Dikeman'; 'Paul Friedenberg'; Brian.Link at Level3.com;
fussball_3 at hotmail.com
Cc: 200q20v at audifans.com
Subject: RE: [200q20v] re: stock bypass valve, TBV



I wondered about the blow-off valve issue and too-rich mixtures as a
result... I plan to install one on my 85 ur-q, as it does not have a
bypass-valve stock and likes to blow induction hoses above 15 PSI boost. I
think the idle-switch will tell the F/TCU the throttle is closed and it
might not inject fuel as long as the throttle is closed. This should 'fix'
any rich problems resulting from the blow-off valve letting metered air flow
by the blow-off valve.

Thoughts?

-glen


-----Original Message-----
From: 200q20v-admin at audifans.com [mailto:200q20v-admin at audifans.com]On
Behalf Of Brett Dikeman
Sent: Wednesday, September 13, 2000 9:50 PM
To: Paul Friedenberg; Brian.Link at Level3.com; fussball_3 at hotmail.com
Cc: 200q20v at audifans.com
Subject: [200q20v] re: stock bypass valve, TBV


At 1:21 AM +0000 9/14/00, Paul Friedenberg wrote:
>Mine seems to go out about every 6-12 months, but I tried a valve
>from TAP, and subsequently bent some vanes on my brand new RS2
>turbo, so I would advise sticking with the stock one. Just replace
>it when you hear the WG "chatter." Blau seems to have a decent price
>of $45. Better than a rebuilt RS2!!

Porsche makes a metal replacement valve that costs about the same.
Call any posche parts place and ask for a TBV for a 996 twin turbo.

It's substantially more durable.

>just a passing thought, but has anyone considered putting a blow off
>valve on in place of the turbo bypass valve (ot throttle overrun
>cutout, what ever you want to call it..)  I really have no clue
>about whether it would work, but it would be interesting to find out

Don't.  Blowoff valves dump metered air.  The result is a sudden,
extreme rich condition which eats catalytic converters.  There is no
reason to use a blowoff valve in a street car.  No reason to use one
in a race/track car unless you've done a lot of other stuff to the
car.  The clowns running around with blowoff valves on their A4's are
going to be real sorry in a few years when they have trashed
catalytic converters...of course, I bet all the A4 performance tuners
will be more than happy to sell them "performance" cat converters to
replace those "restrictive" cats on their cars.

Brett
--
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Brett Dikeman				Systems Engineer
CFN(formerly iClick, Inc)			914-872-8043
120 Bloomingdale Rd.			914-872-8100(fax)
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