[200q20v] RE: [s-cars] blowoff valve questions

[Robert Pastore]

The Tap valve is marketed as both a bypass valve and blow off valve.  The
blow off pressure is adjustable.   Normally, we configure the valve as a
bypass valve ( and should ignore the adjustment feature) by connecting a
vacuum/boost line from the IM to open the valve  when the IM sees  vacuum.

Has anybody tried setting the valve up as a blow off valve by not connecting
the IM line and setting the adjustment to equal the desired maximum boost ?
The valve would still be plumbed to return the blow-off air back into the
system in the same manner as when it is configured as a bypass valve, but
would be actuated by excessive boost pressure in the intake tract instead of
vacuum in the IM. 

Bob

 -----Original Message-----
From: 	Achint Sandhu [mailto:sandhu at nortelnetworks.com] 
Sent:	Monday, June 18, 2001 11:31 AM
To:	'Chris Covington'; s-car-list
Cc:	200q20v
Subject:	RE: [s-cars] blowoff valve questions

	There is a major problem with using a Blow Off Valve instead of a
bypass valve in our cars and this relates to the fact that any air entering
the turbo has already been metered by the MAF. The ECU is expecting this air
to be somewhere in the intake system.

	If the Bypass is replaced with a Blow off valve, metered air will
get lost and the ECU will assume that there is a leak somewhere in the
system.

Cheers,
Achint

-----Original Message-----
From: Chris Covington [mailto:malth at umich.edu]
Sent: Monday, June 18, 2001 10:30
To: s-car-list
Cc: 200q20v
Subject: [s-cars] blowoff valve questions


20VTers,

Has anyone here ever run a blow-off valve instead of replacing their BPV
when it blows?  I see that many manufacturers use those from the factory
(Mitsubishi, Nissan, Mazda) and this could help eliminate our blown
hoses, etc. issues with chipped cars and/or upgraded turbos, since the
pressure is relieved instead of being re-routed.  It seems that
Audi never has though, I assume even with the RS4, RS2, etc.  Thoughts?

Chris
'91 200q20v IA3


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