[s-cars] Hose leak and boost gauge 'tap' location

[Steve Eiche]

Bruce,
No, you are not missing something.  The hole you have isn't large enough
that the turbo cannot spin fast enough to make 19-20 PSIG of boost (your
gauge is correct).  You are spinning the turbo a lot faster than you
would be without the leak, thus adding more lag and heat resulting in
the lackluster performance.  The hole probably closes under vacuum, so
it has little affect there.  Now if the leak were much larger, you would
be seeing the boost fall, and perhaps idle and/or stalling symptoms
under vacuum.
So, your ARE developing boost, just some of that extra air is being
blown out the leak.  You ears are you best diagnostic tool for this
problem, and from what you said, they have worked well to find the
source of the problem.
Steve Eiche

Hey all

need to tap into the collective knowledge database...

hopefully this is an easy one..

I've been noticing lackluster acceleration coupled with a loud
Whooooshing =
sound under heavy boost coming from the right front area of the engine
bay =
on my '93 S4 lately...  Upon further investigation - sure enough - I
found =
a hole about the size of my little finger in the turbo to crossover pipe
ho=
se.

Even with this gaping hole, my boost gauge behaves absolutely normally:
- i=
t reads ~13 in. vacuum at idle and reads ~ 19 -20psi boost under max
accel.=
  (This is with an MTM 270 chip)  So what gives here?  The main reason I
in=
stalled a boost gauge was so that I would know if (when) I ever had a
leak =
in the system.

My boost gauge is 'T-ed' in on the line that runs down to the ECU -
right n=
ear the moisture trap along the firewall  - this is the line that is
notori=
ous for popping off all the time on our cars.

Here is the question:  Am I measuring the vac/boost in the wrong place?
It=
 would seem that this is so.  After all, why is the gauge telling me
there =
is ~19psi boost when this is obviously NOT the case?  DUH - Must be BC I
am=
 not measuring the boost in the correct place.

Where are you guys tapping in to measure vac/boost?  It seems that we
would=
 want to measure vac/boost that is present IN the intake Manifold.

Am I missing something here?

Thanks

Bruce