Boost loss?? (after MC rebuild/upgrade & T3/K26 turbo)

[Ben Swann]

On Thursday, June 13, 2002 2:01 AM, Rick Houck [SMTP:rhouck at neo.rr.com]
wrote:
> Ben,
>
> I have a 10v turbo engine that I rebuilt to install in my 1990 coupe
> quattro, and I have had some teething pains as well. I am now reliably
> running 20 PSI of boost (over atmospheric pressure), which may be 2.3
bar,
> depending how you look at it.
>
> It takes only a small crack opening up somewhere to bleed off pressure. I
> have popped just about every fitting at one time or another, so I would
see
> if you can do some kind of pressure check to find the problem. Don't
forget
> to check the boost gauge line and even the original hose into the ECU.
Also
> check the intercooler joints to see if they may be expanding and leaking.
>
> Good luck.
>
> Rick Houck
> Ohio

Ok thanks for the suggestions.  I have been over all of this, been looking
for over 2 months now before finally consulting this list.  I have not been
able to identify any possible leaks in the intake, iIC's was strapped
already.  I am seeing a solid 18-20 vacuem on my guage at idle.  I am
pretty sure the system is tight.  I keep looking.

Right now my biggest suspect(s) are:
1) The T3/K26 turbo just won't produce the boost.  I have been assured this
is not the case, but this is the major change in the system.  Well I did
open the exhaust, a tad,  but I wouldn't think that would reduce boost so
much, although the upgrades followed the premise of less boost with more
flow = greater power.

2) The wastegate is stuck slightly open - possibly a piece of debris got in
there somehow.  I don't see how to verify this without removal.  Based on
my experience re-installing with manifold etc., wastegate removal is
something that I don't want to get into unless I am confident the problem
is there.  It doesn't completely make sense that this would be the problem
either, since boost spools up incredibly fast, which wouldn't be likely if
the wastegate were open.  Perhaps there is some easy way to disassemble the
wastegate from the top, at least easier than the contortions required to
remove it.

I thought I'd get more feedback on this, but it must have been lost in the
heated theoretical discussion I referred to earlier.  I thought my problem
was relevant, as the T3/K26 is supposedly very similar to the RS2 turbo.
 Now I am not convinced I made the correct decision in my selection.

Ben
'87 5000 tqa - Engine rebuilt incl. following -
T03/K26 hybrid turbo
Elgin 270i260e cam removed and swapped the stock cam back for
 troubleshooting.
adjustable cam sprocket - set for 3 deg retard
new valve seals, lifters & techtonics springs
new piston rings, connecting rod and main bearings,
all new seals.
2-Piece Exhaust manifold, highflow cat and 2.5" Stebro exhaust.
All visible casting flash removed from components.
Mild port and polish to head and manifolds with ports matched.
Bypass valve located in intercooler where untapped hole was with bypass
flow directed toward turbo.
Supplimentary fuel injector installed in intercooler (but not connected to
fuel or 034EFI yet)
 			- injector is inline just prior to throttle body hose.
200 Flywheel, Clutch and Pressure plate, slave cyl.
QLCC chip & Schrapnel Knob and 2 bar SJM spring for control - all were
operating prior to rebuild.