[s-cars] bpv question... (sort of)

[djdawson2 at aol.com]

OK... you're trying to judge the performance of your BPV based on a reading taken in your IM.  That no worky.  The BPV just allows air to recirculate to the turbo.  That recirc path (on stock type plumbing) is basically from the turbo outlet straight back around to your turbo inlet.  The gauge in your IM doesn't see any of this.  When the throttle body slaps shut, the IM does indeed see a large vacuum... and this is reported by your gauge.
 
I 'spose if you truly wanted to report on the effectiveness of a BPV, you'd need a "turbo tach."  This would report the rpm loss by the turbo during shifts.
 
Back to reality... what you're seeing is exactly as expected.
HTH,
Dave 
 
-----Original Message-----
From: Pollock, Thomas <thomas.pollock at amd.com>
To: s-car-list at audifans.com
Sent: Tue, 7 Feb 2006 12:31:39 -0500
Subject: [s-cars] bpv question... (sort of)


Hey s-folk....

wonder if this is normal behaviour...  after the motor rebuild I threw a 710n 
valve in so I could clean and lube the Forge valve I usually use. The car is 
really running quite good but I wanted to hammer it a few times to see if I 
could notice the difference after cleaning, ah, I mean REALLY hammer it. 8-)  
What is strange is that between shifts, on my boost gauge I see it go way into 
vacuum and I almost have to wait a second for boost to have to start to build 
again. Just can't get a nice crisp shift.  I know I'm not shocking the turbo as 
if I had a bad valve (I know that feeling too). 

So, I threw the 710n back in and I get pretty much the same thing. Is it normal 
to go all the way deep into vacuum like this ?

On a side note, I tried human testing (blowing into) both valves. I can easily 
blow open the 710n, not even close on the Forge. 
The car is your garden variety 94 rs convert... I would imagine cars running 
even more boost, the 710n would be leaking like crazy.

thanks in advance,

tom.

back up to (7) Audis !!!  
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