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Old 04-30-2012, 02:09 PM   #1
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Red face 8MM Inconels not big enough

I broke all four 8mm Inconels studs at the exhaust manifold holding the turbo Sat at the track. I had done both Fri. and Sat. when they broke in the afternoon. Also both days at Laguna 2 weeks earlier. That was the 4 track days this year and the setup probably had 8-10 days from last summer. I built a motor over the winter with rods and pistons so as to run 15-16 psi instead of 10-11 last summer. I did change out the 8mm nuts to Stage 8 fasteners so as not to have a loosening up issue and the downpipe is supported. So I don't think 8mm is big enough for serious track running in "A" groups, might be okay with less strenuous driving. Anyway well be calling Trackspeed for the 10mm setup as I went with the ARP 8's from FM as it was their FM11/Hydra kit I bought, second car I've had and put their setup on and love for a plug a play setup and would highly reccomend.
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Old 04-30-2012, 02:53 PM   #2
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Would you mind posting pictures of the studs?
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Old 04-30-2012, 04:43 PM   #3
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I just got done taking the turbo and manifold off. The studs did not break and that is good, as I could hardly believe Inconel would break. With the hooded heat shield on and driving 2 track days, I just saw the stage 8's and the studs hanging in the turbo flange and took it for grantite that they had broken. As soon as I removed the heat shield, youy could see the studs were whole. All 4 has stripped the threads out of the manifold. I remember when I put it in that I told Branden I thought they were a bit on the short side as you couldn't seat the manifold threaded end tight in the manifold and still have enough threads for the sweezed style locking nuts that came with the kit as it didn't leave enough thread sticking out of the turbo flange for the locking part of the nut to grab onto. So it looks like they were starting to wollow around some, what with the different heat expansion rates of the different metals involved and were working on the threads and they finally let go. I had forgot about the length issue when I installed the stage 8's, I could have screwed them in a few more turns but I still don't think enough to seat the studs tight in the manifold. So I guess the moral of this story is to make sure the studs seat down tight in the manifold.
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Old 04-30-2012, 05:33 PM   #4
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Just got off the phone with Bill at FM and they did lengthen the studs from my feed back last summer and now have it so they can be seated tight in the manifold, and he is going to ship me another prepaid and $250 for the manifold and studs, beat the heck out of $475. Anyway should be back on the road shortly.
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Old 04-30-2012, 05:58 PM   #5
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Go 10mm
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Old 04-30-2012, 06:48 PM   #6
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Yeh I was just thinking of that, I can get 10mm from Trackspeed for $155, just have to drill and tap the manifold and drill out the turbo flange. Need to surface the manifold a little for some warpage, probably from loose studs over time.
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Old 04-30-2012, 08:03 PM   #7
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If you are surfacing the manifold and turbine housing, now is the time to upgrade to 10mm.
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Old 05-02-2012, 03:32 AM   #8
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Size matters and I wouldn't try to reuse the M8 holes. M10 inconel with resbond, lockers and forget it.

disclaimer: I spoke to John on the phone and this is what he's doing.
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Old 05-02-2012, 11:28 AM   #9
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I did order the 10mm/with stage 8 fasteners from Andrew and have drilled and tapped the manifold. I had it surfaced and as soon as the studs arrive I should bbe good to go. I don't think there is anything wrong with the 8mm setup if the studs had been long enough to have seated them tight against their sholders into the manifold. These were untouched as far as any damage goes other then the threads having cast iron welded into them from working in the manifold most of last summer and 4 track days this year. I am actually surprised they lasted this long as they were only in the manifold a mere 3/16". Not a good move on my part.
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