5ktq and Boost isn't everything..turbo, cam, flywheel, 034efi..but still needs help.

[Ben Swann]

Scott Justusson stated..
[Boost isn't everything.  It's engine design and airflow.]

And this was a major driver to the work I recently undertook in rebuilding
and upgrading my pearl '87 5ktq avant.

I have been following these flywheel and turbine and similar discussions
with attention trying to see how some of this might relate to or help the
outcome of my project, and as well I will provide my input based on the
recent experience of a complete teardown and rebuild with some major
goodies added in.

Now, I recently completed (well the car has been being driven for over 3000
miles anyway) a major overhaul with an attempt to improve upon what was
already a nice running car - my pearl 5000 cstq avant.

Here is a brief recap of what was done:

'87 5000 tqa - Engine rebuilt incl. following -
T03/K26 hybrid turbo
Elgin 270i260e cam (until yesterday when I swapped the stock cam back in).
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 turbine.
Supplimentary fuel injector installed in intercooler (but not connected to
fuel 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.

I am reluctant to say results have not been overwhelming, but am hoping
that this post will lead to the potential that remains to be unleashed.

First off,  the lighter 200 flywheel does not hurt idle or drivability.  No
more to be said on that.

After running in the cam and breaking in the rings and initial debugging,
 I took the car on a long 2000 mile cruise.  When I first gave the car some
good test runs, it was obvious that the engine flowed freely and revved
straight to the rev limiter.  The bypass was proved to be working by the
number of times I had to tighten the fittings that would blow off between
the valve an the turbo.  By now I have everything well  tightened down.

There is relatively no lag in the setup and the boost spools to 1.3 bar
easily by 3k RPM.

Now the disappointment has been that the engine no longer develops the
expected boost.  I played with the schrap.knob and even  resorted to
disconnecting any wastegate control whatsoever and the most I have observed
is 1.7 bar(~11 PSI) and that is when going full bore over 5k reaching
speeds that ask to get thrown in jail fast.

Prior to the work, I could easily dial in over 2 bar of boost and had set
to around 15-18 PSI, and reached the set boost around 4k RPM.  A leaking
exhaust manifold(small cracks) and gasket prompted me, or should I say,
gave me the excuse to perform this major undertaking.

After much trial and error, I tried installing an adjustable cam sprocket
to see if it made any difference.  To my surprise, advancing the cam did
little to improve my low end performance, and retarding really opened up
performance with little low end detriment.  It was also amazing that the
gas mileage was phenomenal (not what I expected, and I could easily see 40
MPG average on the highway, and 27 around town).  But still, boost seems to
max out - I don't even see 1.8 bar(measuring both guage and dash).

I spoke with Elgin cams and they agreed the cam might be a little hot for
my needs - details missing here.  So I put back in the stock cam.  Well of
course, the car idles better, and to my surprise fuel economy dropped back
down.  I still only get 1.7 bar.  So it wasn't the cam - I thought I might
be losing boost due to too much overlap.  I will likely get the cam
reground to a 260/254.

Now I am at a loss as to why - why is this setup only developing 1.7 bar.
  I have been over the system for leaks of any sort.  I am pulling better
vacuem than prior to rebuild.  Engine compression tested fine(150 =/-
2PSI).  I did find that the stock cam helped reduce oil consumption - I
think the lift on intake was messing with the seals.

Although the T3/k26  turbo is designed to make the boost spool up quicker,
I also understand that it should be sufficient for way more boost than what
I am seeing.

The only thing I can possibly figure is maybe the wastegate is
leaking/stuck slightly open - I haven't yet checked it. It was definately
sealed tight when I re-installed it.  Is there any way to tell if the
wastegate is partly opened without competely removing it?

I don't have access to a dyno, but I know the car was faster before the
rebuild, when it was choked but making 2+ bar, which it did without much
effort on the stock, high mileage, k26 setup, with leaky manifold and
choked exhaust.  Ironically, the other '87 avant I have feels faster, and
it only has a charlie spring and chip good for 1.8 bar.

Any clues to helping me find the lost boost in order to unleash this cars
potential would be greatly appreciated.  At this point I don't even reach
the point where I need the 034EFI injector operational.

Ben