[s-cars] Stromung Exhaust Install Tips

[Scott Justusson]

As Jeff points out with 14feet of exhaust the hot expansion is
significant.  The best way to install that exhaust IME, is to have all
mounts forward of "hot" position.  Vision: The tabs/mounts are not
straight down from the body to the exhaust, but the body tab would be
aft of the exhaust tab.

WRT mounting and vibration, the swap from the 3in turbo back to the
stepped downpipe seemed to have created more fitment problems.  Not sure
if it's the jig (I suspect so), or the combination-sizes of pipe, but I
have much better luck with the all-3in DP than the 2.5>3in DP.  Remember
too, that downpipe is a multiplane bend, which could require some
tweeking.  I don't necessarily blame the exhaust, Audi did 2.3/8 pipe
for a reason - it's tight stock, and turbo cars have a lot of heat
expansion.

A flex pipe performs two functions, isolator and "slopolator".  It
removes the rigid connection of the whole exhaust from the engine.  As
such it allows for a bit more slop in the exhaust.  For the DIY install
most of these Stromungs tend to be, it's not a bad addition.  I don't
believe it's necessary, and I find flexpipes don't last long, and are
easily destroyed just trying to remove them for some other service (btdt
with a lot of Audi V6 cars with stock flexpipes).

IIRC my last install of the Gen IV 2.5>3in DP, the bend is really too
tight under the driveshaft, and this causes a problem in the connection
at the transmission bracket mount.  Specifically, installed "as shipped"
it's under stress.  For several years with all 'bolt on exhausts'... I
put in the system, then take it to my exhaust guy (30 years of exhaust
experience) and he does what it takes to get the systems right.
Heat/tweek brackets, remount them, whatever.  Usually less than
30minutes, he's got it where it should be = right.  

Perspective:  I don't consider this a big deal, I do think the stromung
jig should be redone on the 2.5>3in DP, and I suspect no flexpipe is
necessary.  That said, I've also installed a 5000USD Sportec RS6 exhaust
that was oxymoronically "bolt-on", so I just get them all tweeked
correctly.  That 5/8" of pipe diameter increase on the stromung, makes
things really critical in terms of fitment.  I stopped d**cking with
bolt-on exhausts years ago when I watched my exhaust guy move 2 hangers,
bend another, and it was perfect in 20minutes.  I was over 3hours
looking for that.

HTH and my .02

SJ




-----Original Message-----
From: jpb3 [mailto:jpburns3 at gmail.com] 
Sent: Friday, March 20, 2009 9:34 AM
To: Brian Armstead
Cc: Scott Justusson; S-Cars; jeff postupack
Subject: Re: [s-cars] Stromung Exhaust Install Tips

Guys,

Scott can you explain a little more about "getting the exhaust mounts
installed slightly forward position"?  I have been called dense before
so if you can talk a little more about this I would appreciate it.  Do
you mean the rubber hangers or the position of the "tang" in the
rubber hanger?  Or something else entirely?

I have had issues with the gen IV cat hitting my tranny under hard
accel/decel, there is very little clearance between the two and I have
been under the car twice since installation trying to configure the
connections to provide more clearance.  New motor and tranny mounts
were installed <10K miles before the stromung install.  My next step
is to source a flex piece such as what is now being provided on Gen V
DP to see if that will remedy my problem.
....
Mine is going back on as soon as I get the system sorted out.

Even with the minor annoyance of the above issue I still have no
regrets about the purchase, the sound is just that good :)

John