[s-cars] RS Tuning tube header cracks at second track event

Tue Aug 9 09:13:12 EDT 2005

Ok, I get it. I'll make sure to pay special attention to how the WG is sorted on the next one. Now onto the other issue of the car backing boost off from 24-26psi to 10-12psi. I forgot to mention that it also did this on the first day at the instructor clinic when we were just driving the track at 50% to get used to it. We drove about 10 laps where I never got into WOT and my temps were fine but when we finally did decide to step it up boost had already been lowered to 10-12psi. So I assume my problem is a sensor or something that triggers once the car is totally warmed up but not just when I'm running at WOT. Any idea's?

Elijah

-----Original Message-----
From: Trevor Frank <tfrank at symyx.com>
To: djdawson2 at aol.com; elijahallen92 at aol.com; s-car-list at audifans.com; es2 at audifans.com
Sent: Mon, 8 Aug 2005 17:03:07 -0700
Subject: RE: [s-cars] RS Tuning tube header cracks at second track event

Ya..so I just got done building another header for a guy with a 1.8t motor in a formula atlantic.  He had a steel header that blew holes everywhere, I replaced it with a custom 321 peice, nice 4 into one collector etc.  But I didn't do a great job of holding down the waste gate, the turbo held on just fine, but we kept on ripping the waste gate off of the thing right at the top of the weld on the merger.  So I made a big brace a lot like what lehman did, from the turbo flange to the wastegate flange.  still it ripped it off.   My final conclustion, is that the turbo is frist held by all of the pipes and welded onto a nice big merger with lot's of weld area and in the right orientation.  The wastegate is welded at 90 deg to the merger, in kina a weak and high temperature spot.  with the waste gate mounted a few inches above it and a lot of moment on that arm really.  as well since the tube is so short from the merger to the waste gate the stress that is built in from the waste gate's weight is almost directly placed on the weak point above that weld and onto the collector.  I suspect that if you put a bent section of tube to connect to the waste gate you might be ok, or even lengthened it and then held the wastegate fairly ridgedly.  We didn't see this problem in practice, almost always in the race where 3g in a turn is probably the lower end on this car.  I suspect that Elijah was pushing his car a bit around the track maybe even some banking and that 10 pounds turned into 30 with a moment arm and at temperatures that really did some damage.  We had a flex cupling right after the wastegate and it was a tial so lighter and shorter than what we have on our cars, and still.   The solution was what I like to think of a the bigger hammer, Javad had initially requested this but in my infinite wisdom I kinda shot it down, thick wall 316 weld ells and then I used his planer merger design and put some serious gussets from the merger to the wastegate.  

The update is with the steel header basically the same design as the 316 he would have holes after practice and meterial failures everywhere.  With 321 thin wall, everything held accept for the waste gate tube, witch again I think I just made to stiff, to much tranfer of the stress and strain.  With the 316 in a similar design and thickness of the steel, no material failures and no "ripping" of the wastegate tube off the header. 

Just a few words from my lesson learned in the last few months.  Oh and he finnally won and finished a race!
-----Original Message-----
From: djdawson2 at aol.com [mailto:djdawson2 at aol.com] 
Sent: Monday, August 08, 2005 2:52 PM
To: Trevor Frank; elijahallen92 at aol.com; s-car-list at audifans.com; es2 at audifans.com
Subject: Re: [s-cars] RS Tuning tube header cracks at second track event

Trevor,
I'd buy in to the weight arguement, IF the crack had occured on one of the main tubes.  But on the WG pipe?  The only weight there should be the WG itself.

Not to beat a dead horse, but these headers should hold up.  I now have 22k miles on mine... much of which I would never consider to be "normal" use.  My use has included numerous extended WOT throttle runs that have produced 1500+ degree (F) EGTs... repeated dyno tests... and many use situations that have resulted in the entire header glowing red, as well as the turbine housing and the first 8-10 inches of the DP.  My header has no additional bracing or supports to reduce stress on the header.

If Elijah's WG pipe has failed, I'd have to guess that he's missing a flexible pipe between the WG and the main DP body... in which case, this type of failure should be expected.
Dave

-----Original Message-----
From: Trevor Frank <tfrank at symyx.com>
To: djdawson2 at aol.com; elijahallen92 at aol.com; s-car-list at audifans.com; es2 at audifans.com
Sent: Mon, 8 Aug 2005 14:25:13 -0700
Subject: RE: [s-cars] RS Tuning tube header cracks at second track event

Even with something flexable the weight it'self in a turn is enough.

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of djdawson2 at aol.com
Sent: Monday, August 08, 2005 2:22 PM
To: elijahallen92 at aol.com; s-car-list at audifans.com; es2 at audifans.com
Subject: Re: [s-cars] RS Tuning tube header cracks at second track event

Do you have a flexible section of pipe between your WG and your
downpipe?  If not, that is why it failed.  Otherwise, I think you are
having excessive EGTs.  It is pretty odd that it cracked on the WG pipe.
Good luck, Dave

-----Original Message-----
From: elijahallen92 at aol.com
To: s-car-list at audifans.com; es2 at audifans.com
Sent: Mon, 08 Aug 2005 10:15:46 -0400
Subject: [s-cars] RS Tuning tube header cracks at second track event

Hey guys, just got back from a 3 day event at Waterford Hills. The car
ran good

most of the time but I did have a few issues. The first one was that the

subframe bolts would not stay tight and when I went to re-torque them I
over

torqued one and it broke off up in the frame. Luckily there was another
coupe

there that had an engine blow and was being trailored home so I was able
to get

a bolt from him to continue the event. I got a bolt extractor and
drilled and

extracted the bolt only having to miss one  rungroup. I put a bunch of
lock

tight one them and they seemed to hold. The other problem I was having
was after

about 15 minutes on the track the car would dial boost back from
24-26psi down

to 10-12psi. I never figured out why it was doing this but all I can
think is

the EGT's were just getting to hot. My oil and coolant temps were fine
and

although I don't have an intake air temp sensor the tube coming out of
the cold

side of the intercooler stayed fairly cool. On the last
  day I felt like I had a boost leak and could hear a hissing sound so I
pulled

of to check and noticed a nice size crack in the tube header on the tube
that

goes to the WG. This car has only been to two track events so I'm not
real

excited about the build quality of these headers. Hope the others
running them

do some major looking over and maybe some more structural welds like HAP
did.

I'll be having mine welded for now but am going to have a better one
made soon.

Any feedback on the boost backoff is greatly appreciated. Thanks,

Elijah
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