[s-cars] Track Tips - Stromung and Big Red Rotors (993tt)

[jeff posto]

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[ Picked text/plain from multipart/alternative ]

 Hello Bruce and the S-car community.
With reference to Bruce's experience at the track, and his stress cracks in=
 the Stromung downpipe. This is the first report I have heard to date.
OF course, I called Stromung to investigate and report to you what's going =
on.
Bruce has a (highly) modified RS2 car and runs it at the track occassionall=
y=2E This environment places high heat stresses on the entire engine and ex=
haust system, but you all know that!
That is to say, higher than OEM, or MTM Stage III or IA Stage III.
IT stands to reason that the higher we crank the engine output to RS2 level=
s, that highest heat output (in BTU's) will be produced. Mance's famous 398=
 BHP car or Hap's car are probably among the highest.
(Say HAP, have you inspected for stress cracks in Evergreen today?? )
The trick is to anticipate the heat load and handle the heat properly.
Bruce also owns the GP#1 system, developed in early 2001.
At that time, we did not specify in particular, the heat index likely to be=
 exposed to the exhaust. We just presumed Stromung would handle it.  We wer=
e driving at a cost effective solution for aggressive street use and occass=
ional track use, keeping the cost low was imperative.
Now what to do..
Stromung tells me that it is possible to promote stress fractures in racing=
 situations and has experienced this 2 times in the early days with a tuner=
 in the US known for hot rodding our cars. In those days, the downpipe was =
replaced once per racing season.  Stromung immediately recognized a similar=
ity when I estimated the Bruce M RS2 car to be about 350+ BHP and they reco=
mmended two scenarios.
1: IF you built up to RS2 levels AND are racing the car, replace your downp=
ipe at 18 month intervals, as this is typically done in the racing scenario.
In my experience, strictly street, my 1993 IA Stage III is plenty fast for =
me, and shows no signs (at all) of stress fractures in the downpipe. I've r=
un my "SS" system since March 2001. Downpipes are the least expensive compo=
nent of the "SS".
2: IF you built up to RS2 levels AND are racing the car, Construct a better=
 downpipe in particular, fabricated from 312 stainless steel. This is a muc=
h better material that will last 2X longer. But even this will eventually w=
ear in racing situations after 3-4 years. This part bears most of the heat =
mind you.
All this comes at a nominal cost increase mind you, especially if we fabric=
ate this from 312 stainless. In Bruce's case, Stromung will lavish some cus=
tomer support to analyze this situation.
more to be advised soon, please write me off list if you want more detail a=
s I will liberally share my experience here.
JEff Posto

  Bruce <brucem105 at comcast.net> wrote: I just had to buy new rotors for big=
 red kit after lots of track days. Major
warp, and currently using Pagid orange. They are two piece units from
'96/'97 Porsche 993tt. I got them from ECS at $165 each.

I assume this is reasonable price, and should I know anything or just a
standard rotor swap after replacing hats?

Second item is my Stromung exhaust has now cracked two hangar brackets, and
developed stress cracks that were open to outside air around both welds at
the downpipe (for "L" bracket and for actual downpipe attachment). I'm sure
it's related to amount of track time lately, and maybe heat as well.

I'm also checking motor and trans mounts to make sure they are not bad and
allowing exhaust to flex too much, but just wanted to give you all a
heads-up to check in case you have the unit.

Thanks all.

Bruce

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