[s-cars] Two Words

[JShadzi at aol.com]

--
[ Picked text/plain from multipart/alternative ]
Ray, yes, I"m not a Porsche Engineer...boy, really got me there...will all
the Porsche engineers on this list that handily and regularily dole out
advice please come forward?  (no, the jump suit that your wife sewed a
P-patch on doesn't make you a qualified Porsche expert... =)

We can salvage some technical meaning from your email that point us all in
the right direction, however...

If Porche had used some of the tuning-tech that many turbo-tuners impliment,
the RS2 would have come from the factory with a poor K24 running 35psi boost,
straining to make some 300hp with terrible efficiency, high temp intake
charges that would be prone to detonation, and thus retarded ignition timing,
etc, etc.  Flow, for the given pressure, would be lower aggrivated by the
turbo's efficiency limitations.

Because Porche understands how pressure and flow interact to make power, I'd
say they were precicely in line with what my post asserts.  In fact, you
imply that I was saying something converse to the RS2's tuning philosopy, but
I'm pressed (pun intended) to see when I did that - I think Porsche's
approach in the RS2 was precisely correct.  By determing a targeted  power
output (not just "uhh....more"), they developed an entire _system_ around the
venerable 20v turbo motor (not much different if at all than the AAN in fact)
with upgraded injection components (bigger injectors for proper fueling),
less restrictive intake system with bigger intercooler, less restrictive
exhaust sytem with manifold, and larger turbo (yes, there is more lag than
the K24) with a compressor map well within its intended application of
efficiency.

Now I ask, how much boost would an AAN with K24 have had to run to get to
315hp and could it even?  The RS2 turbo and reconfigured engine "system"
makes about 40% more power with marginal increases in boost pressure.

Another example, my car (ahem...), see <A HREF="http://www.80tq.com/Dyno.html">http://www.80tq.com/Dyno.html</A> , I have
a dyno comparison of my car running 15psi boost and an Urq with K24/CIS
running 15psi boost, my car makes 230hp at the wheels, the Urq makes 150,
_same_ boost pressure.

The major limitation the Porsche engineers had was that they were dealing
with a mass produced passenger car, and thus smoothness and driveability were
critical in the design equation - something that many of us can overlook.
There is no question, however, that in order to continue to push the power
envelope of a 2.2l motor into and past the 400hp range, smoothness and
driveability will continue to be sacrificed, this is a reality, as does
become turbo lag, and running even an RS2 turbo to 30psi may keep smoothness
but won't be contributing much making more power.

BTW, I'd be happy to share my tuning resume with you, might not get me in at
Porcshe, but gives me the ability to draw information from marginally helpful
emails otherwise.

;)

Thanks,
Javad
80tq.com

In a message dated 2/11/2003 7:10:54 AM Pacific Standard Time, ray at s-cars.org
writes:

> Javad,
>
> How Porsche managed to put together the 2.2l RS2 motor with PHENOMENAL
> DRIVEABILITY AND RELIABILITY is something that some us look for in
> "building" our motors.  But, I tell you what.  I'll make a call right now
> and get you in over at Porsche.  What did they do without you all these
> years?
>
> Two words:  MARGINAL UTILITY.
>
> :`)
>
> Ray Tomlinson