[s-cars] Bypass valve questions

[thomas.pollock at amd.com]

One more BPV data point.  (this could get confusing so read slooowly) I
recently replaced the stock BPV in my for sale 94 S4 with a piston type
Forge 007.  I felt performance was degraded a little cause I "thought" I
could feel the dreaded turbo stall between shifts. (this is only a guess but
I thought maybe the stiff spring in the Forge was too much for the vacuum to
pull open)  Now I recently bought another S4 with full RS2 and it had the N
variant Bosch unit. The car ran flawless, pulls all the way, doesn't seem to
bleed off etc. Decided to throw the Forge valve in the new car and the stock
N variant in the for sale car. The new car (RS2) still runs flawless, even
"maybe" a bit smoother etc with the Forge BUT, I don't get the stall between
shifts like I did when it was on the for sale car, which is weird cause I'm
pulling the same exact vacuum.  And the for sale car runs better with the N
variant Bosch !   Looking at the boost gauge the N-type holds better than
the A-type, as good as the Forge but without the turbo shock.

What does all this mean ?  Haven't got a clue but both cars now seem to be
happy so I'm not touching them again....

tom.


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