[s-cars] Waste gate creep

[Richard Tanimura]

Robert,

"Schraplkelknob" sounds disturbingly close to "shrapnel knob". Tuning ones
thoughts to handgrenades and the old "dial-a-death" variable boost systems.
But 120,000 incident free miles is not too shabby :-)

Can you send me the write up.

Rich



-----Original Message-----
From: s-car-list-admin at audifans.com
[mailto:s-car-list-admin at audifans.com]On Behalf Of Robert Myers
Sent: den 11 mars 2003 12:50
To: Richard Tanimura; s-car-list at audifans.com
Subject: Re: [s-cars] Waste gate creep


--
[ Picked text/plain from multipart/alternative ]
Richard,

Without studying the web site in detail, it looks very much like Paul
Timmerman's Schraplkelknob "boost controller" which uses a small pressure
regulator to apply boost pressure to the top side of the wastegate
diaphragm.  This helps keep the wastegate closed until the pressure setting
of the pressure regulator (plus the spring pressure) is reached.  This
provides a simple route to greatly increased boost levels.  It is a simple
but elegant technique.  I used it with great pleasure for about 120,000
miles (total) on two different '89 200tq's.  The regulator requires a
method to eliminate the overboost fuel cut-off.  This can be accomplished
in several ways.  Many of these involve lying to the ECU about the actual
boost pressures.  This, in turn, can potentially lead to excessively lean
mixtures and correspondingly high combustion temperatures and burnt
valves.  Not, however, IME.

I can provide a detailed write-up if desired.

At 09:57 AM 3/11/2003 +0100, Richard Tanimura wrote:

>Being somewhat of a waste gate creep myself, this caught my attention.
>
>I recently saw a pneumatic system to prevent the wastegate from sneaking
>open = creeping. Looks cheap and simple. The idea is that boost comes on
>earlier because you don't leak any air to the wastegate until you hit a
>target pressure. It is more on-off rather than gradual. Here is an article
>http://www.autospeed.com/cms/article.html?&A=0670 Anyone tried this kind of
>solution? Good? Bad? Ugly?
>
>Rich
>
>
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I've been wondering... Who would Jesus bomb?

Bob
*****
  Robert L. Myers  304-574-2372
  Rt. 4, Box 57, Fayetteville, WV 25840 USA  WV tag Q SHIP
  '95 urS6 Cashmere Grey - der Wunderwagen   ICQ 22170244
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