FW: [s-cars] Stebro vs. Stromung exhaust

[QSHIPQ at aol.com]

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3 psi backpressure is about as low as you are going to see with any system
with mufflers attached to it.  IME, you address 6psi and above to realize gains.
 IMEII, a set of high flow cats onto the stock audi S car pipes will all but
negate actual performance measure differences between mongo and stromung.
The key is to measure backpressure just prior to the cat/cats.  My measures
indicated that to realize a performance gain over that juice can, two of em is
bettern one.

Bottom Line:  Audi builds darn nice turbo exhausts from the factory.  You can
go "bigger", but really tough to equate that to "better"

HTH and my .02 arbitraged thru the peso

Scott Justusson
In a message dated 5/27/2003 7:32:10 PM Central Daylight Time,
mlped at qwest.net writes:

Jeff, as Brian points out, it looks like the Don, Frank Amoroso, once put
together some similar data.  Compare what you find in the article &its
conjecture and conclusions with Frank's info below.

I'd say that by comparison to the 94 WRX in Knowlton's article, it looks to
me like Audi already did a pretty good job with the UrS4/6's stock system.
3.25 psi of back pressure at 16 psi of manifold boost at ???? (rpms not
given but I'd be guessing at least 6K) vs. the WRX's 8.7 psi of back
pressure to make @ 10 - 11 psi of intake manifold boost at 7,000 rpm.
Roughly half the back pressure, twice the boost in Stock system vs. stock.
Using Frank's figures for a "slightly" modified stock system, i.e. "Euro
Resonators", no measureable back pressure (? perhaps outside the
"sophisticate" VDO test gauge range of sensitivity) at 16 psi of manifold
pressure, and still less than 4 psi, i.e. a vibrating needle guess at 3.25
psi back pressure, at up to 30 psi of boost, .... still all on the stock
pipes.

Now, if some one can (a) come up with some comparable data for the single
turbo back 3" system; and (b) produce a simple, elegant formula, something
like E=mc^2 or equivalent, to apply to how, if at all, this might affect or
determine PR's in Turbo maps &/or power potential realized or lost,... why
what a wonderful world this would be.

Mike "just reinventing the wheel" Pederson

-----Original Message-----
From: Brian Powell [mailto:brian at atomicham.com]
Sent: Tuesday, May 27, 2003 1:27 PM
To: mlped at qwest.net
Subject: RE: [s-cars] Stebro vs. Stromung exhaust


Mike,

Frank has some of this pressure data up on the urs4 site (about
half-way down):

<http://urs4.com/technical/engine/UrS4_exhaust.html>

He measured 3.251 psig of back-pressure at 16 psig of boost on a stock
setup.

Cheers,
Brian