[s-cars] Waste gate creep

[QSHIPQ at aol.com]

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[ Picked text/plain from multipart/alternative ]
Boost surge is a common problem with all these turbos.  I shared with MP and
another bigoturbodude at Steamboat that you guys probably have a WG problem,
specifically, big turbos on small motors need big wastegates at part
throttle.  The test for this is to find out if your WG is open during these
part throttle runs.  You *should* have a pressure differential between pre
and post T-body to some extent, however, in an ideal world there isn't one.
The reason you don't have a pd=O, IMO, is that the turbo is still producing
massive boost with a WG fully open.  At part throttle, the turbo is still
spooling up and the WG is open, causing a PD between pre and post throttle
body.  Remember too, if your WG is fully open during these part throttle
"surges", it's a moot point (premature?) which boost controller you attach to
it.

Test WG (stocker would be a DC ck, at 90%+DC, WG is open fully).  Change
wastegate to happersize.  Don't be fooled into thinking all WG are the same
on audis.  They aren't.

SJ




In a message dated 3/13/2003 12:53:27 AM Central Standard Time,
CaptMagu at aol.com writes:

Bob

Boy,   you sure do like to respond. First of all, my custom software is set
at 28psi+. The Apexi regulates this back to 22/26psi. I do not use the WGFV
because of WG creep. Although I run the Pederhousen Big MAF I still get the
MAF cut when I exceed parameters. These are not stock parameters!

Secondly, the boost surge I have experienced, is also being experienced by
all the big turbo users that Mike Pederson and I have talked to. Yes, these
include the Innovative turbo users also. More than a turbine section problem
the suspect now is the intake manifold and throttle body. We have a
significant pressure delta on either side of the throttle body. This delta is
enhanced whenever you lift the throttle while on boost. It is further
enhanced when the turbo is under load(as in climbing an incline). My everyday
drive has me climbing I-70 from Denver to Evergreen at over 8000ft. My boost
surge can be severe under these conditions.

I have another possible fix under development and I'll report back when I
have data.

Hap, livin the surge in Everboost, Maguire