[s-cars] Have some questions and need opinions.

[James Bufkin]

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Hi Robert,
here are some answers to your questions.  As straight to the point as I can be.


>I assume you have already verified the basic mechanical condition of the
>motor -- i.e., a compression test, check to make sure the rs2 turbo is in
>good shape, a careful check to make sure the t-belt isn't one tooth off,
>spark plugs (USE AAN plugs), and basic condition of the ignition system,
>etc.  Did you monitor fuel pressure during the dyno runs?

Both fuel pumps were on during the dyno.  Fuel pressure did not waver
during the run. Fuel pressure was very high and consistent.   I haven't
checked compression.   I do not know the compression ratio of the
engine.  The RS2 turbo looks good.  The watercooling plugs were not used
(this car was running an air cooled RS2 turbo).  The wheel spins freely (no
apparent coking).  There is a slight 1mm chip at the corner of one of the
vanes on the compressor wheel (would this cause that much HP
loss?).  Haven't checked the T-belt or the engine timing.  Engine ignition
and spark looks good.  The cap, wires and rotor look fine.  Car starts
easily and idles smooth.   Car also runs smooth.   I am going to have the
RS2 rebuilt.

>Finally, are you running an AAN ECU or other?   Did Lehmann mod the ECU to
>run rs2 chips, or were the Lehamnn chips just installed by Bruno?  The rs2
>ECU has different resistor values, and native rs2 software will run rich
>in an AAN ecu with the matching resistor values.
Don't know where the ECU came from.  I've been told that Lehmann supplied 3
ECUs or perhaps chips for this car.  Two of them actually sent the engine
into safe mode.  Either way it seems somewhat FUBAR althought the details
on the engine's origin are sketchy...    Only other person who has looked
at it was Ned Ritchie who gave it a thumbs up.

>Also, without some insane fuel pressure, the stock (aan) injectors simply
>cannot flow enough fuel to mathc and take full advantage of the rs2
>turbo's airflow capacity........but since you seem to be runnign rich
>already, maybe the injectors arent' stock.  And the rs2 turbo is capable
>of efficiently running boost levels above the 1.5 bar boost where the 2.5
>bar sensor is saturated.....so you leave a lot of horsepower behind
>running with this chipset/map sensor combination.   As a point of
>reference, Frank Amoroso, running the same rs2 setup I have in his 93 s4,
>dynos at 325hp at the wheels not correct for shit.
My car hits 1.7 bar and if I had to take a guess is running rich as
anything at 1.7 bar.   I don't know the fuel injectors.  I can take a
detailed photo and you guys can comment if that is useful to you.   I'm
going to do a static pressure test of the intake system at 24psi and verify
I don't have a leak in the intercooler or something similar which would be
difficult to detect.

><http://home.austin.rr.com/bufkin01/turboremoval.htm>http://home.austin.rr.com/bufkin01/turboremoval.htm
>


Thanks for the comments,
James B.
Austin TX



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James Bufkin, P.E.
Bufkin Design & Engineering, Inc.
Austin, Texas
ph: 512-236-8070
fax:  512-480-5927
cell:  512-914-2659
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