My BTDT re. Upping the boost in a 5ktq...

[ben swann]

I don't know why this didn't make it to the list earlier, but I took
the time to write it, so I am resending it...

Taka, Steve,

Just offering up what I have learned the hard way, and by trying quite
a number of things to arrive at what was a sweet setup on my '87 5000
tq avant, before it met its demise.

The MC-1 will be fine to at least 16 PSI.  I have run higher with
no problem, but say 16 because that provides a good level of safety.  I
have run over 18.  But unless conditions are ideal, you will start to
encounter detonation and subsequent engine damage.

So, I had the opportunity to test several of these cars with friends'
help in order to conclude that 16 PSI is the magic number.  That
assumes the basic operation of the car is sound and everything is
tight, ie. no leaks, good injectors, etc.

A lot can be done to improve the breathing of the motor, but it is
synergistic.  Maximum gains will occur when manifold, port/polish, cam,
removal of restrictions, free-flow exhaust, and improved turbo are all
done at the same time at great expense.  More power is achieved not
necessarily by increasing boost, but by allowing better breathing.
Then more power is being made by the engine over the RPM spectrum so
any peak numbers would not tell the story, since the engine is pulling
harder all the way to the redline.

Yes upgrading to EFI is a good idea, and I give a lot of credit to
Javad above for helping me plan and implement my setup.  However, there
is a lot which can and should be done before adding more air and fuel,
nd I never felt it necessary to turn on the extra injector, which would
have effectively added Electronic fuel injection to the CIS system, by
tapping directly off of the main fuel circuit.

I don't know what Ned's chip does exactly, but if like the QLCC chip,
more power can be gained by augmenting with a resistor of around 4k ohm
and I've recomended a variable setup to dial in the optimal setting.

A stiffer spring is certainly the first way to keep the wastegate
clamped and for longer.  In this case power is developed sooner, but
does not necessarily facilite greater top end- well maybe a little.

A pressure transducer (schrapnel knob) is a good way to dial in more
boost than the chip facilitates (1.8bar?).  I had mine set to 17 psi
using QLCC chip and about 4.2K ohm resistor mod, which kept the fuel
pump from shutting off too soon.  OK, so it does screw with the digital
readout, but not that badly, and one should rely on a guage to really
see what is going on.

At that point it did become necessary to add fuel for any higher boost
or power.  This can be acheived with supplimentary injector and
controller such as Javad's 034efi.  I had not gotten around to testing
this, as the car met its fate shortly after I hooked up the injector -
bummer.  The car was approching 240HP by my estimations, with a large
amount of torque relative to stock.  No I don't have numbers, but I
know what stock was (~ 162HP) I know what 1.8 bar chip is (220 HP) and
I know what I had was significant over those.

Again, after the chip and a spring, the gains to be made follow the low
of diminishing returns on your investment.  All of the port/polish,
cam, exhaust, etc. that I did to get that last extra bit of power cost
far more than it did to take the car to low 200 range.

Some empirical data:

Before breathing mods, engine mostly stock - ecngine pulled to around
6K and then power dropped off. Boost was set for 16 PSI as determined
optimal.

After I did the upgrads(listed below) the engine pulled abruptly to the
RPM cutout in first, second and third gears.  I did have to re-adjust
the knob to arrive at yet again the optimal boost setting of 16 psi.

Conclusion - more perfomance was being made over the RPM by enabling
better breathing ( exhaust, headwork/cam, turbo, etc.) over stock.  I
had nothing but gains on both low end and high end, and the car shined
when pulling the fully loaded trailer.  Low end performance was as or
more important to me as top end.

I did not feel justified in yanking out my CIS system.  I feel with the
setup I was using, had I been able to use the 034EFI and supp.
injector, that I would have had low 300 HP or at least high 200s on
tap.

If you are not made out of money, then what I am saying makes sense, I
was able to do most of this on a tight budget.  My first round of
upgrades costed under $500 to gain 60 HP or so.  My second round of
upgrades costed more than the car.  It was worth it, IMO, but I
certainly lost the added value when the car got totalled when another
car made a left turn right in front of mine.

Ben

BTW I have the injector and controller mentioned available as I doubt
I'll be using it anytime soon, unless I include with the engine, for
sale:

The 1987 MC-1 tq Engine rebuilt incl. following -
T03/K26 hybrid turbo.
Elgin 260i254e cam
adjustable cam sprocket -  set for 0
new valve seals, lifters & techtonics springs
new piston rings, connecting rod and main bearings,  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
Supplementary fuel injector installed in intercooler
           controlled by 034EFI
 - injector is inline just prior to throttle body hose.
200 Flywheel, Clutch and Pressure plate, slave cyl.
QLCC chip with variable resistor modded ECU,
        Schrapnel Knob + 2 bar SJM spring for boost assist and
           control – currently set for 16 PSI.

Allright - back to work!

Date: Mon, 03 Feb 2003 21:15:24 -0500
From: TM <t44tq at mindspring.com>
Subject: RE: Upping the boost in a 5ktq...
To: 'Stephen Ankney' <ankneys at hotmail.com>, quattro at audifans.com

Steve-
IMHO, running higher boost than the 12psi or so that you're running now
on stock fueling and engine management is not going to work well. The
CIS system can't provide enough fuel nor does the ECU have proper
management maps for what you're proposing.

Also, if you do the resistor/zener mod, you'll defeat all overboost
protection, so if the car does run lean due to a fuel problem, you'll
blow the engine.

Running the largest hot side will kill your spool up times- you want a
smaller hot side, like the RS2 turbo, otherwise you're increasing lag.

You should ditch CIS and go to standalone engine management and EFI if
you want big power. Talk to Javad- he's running something like 300+ hp
in his 80tq with EFI.

For the best throttle response, you should go to a tuned-pulse
equal-length header and the most free-flowing exhaust you can bear.

Taka