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Old 02-16-2007, 12:58 AM   #1
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Default Stress relief on Manifold?

I know when you have a mild steel mani that its goning to expand quite a bit and stress cuts are nessicary, and today I was told that my stainless manifold should have reliefe cuts aswell...Opinions?

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(and the turbo flange is in need of machining I know)

(and no those aren't my hands hahaha)
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Old 02-16-2007, 01:09 AM   #2
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You don't have to with your manifold. The log isn't going to change that much throughout it's heat cycles. It wouldn't hurt but I have never seen a log with relief cuts and the physical properties of stainless make it even less necessary assuming your flange is stainless as well. You could make the cuts and it wouldn't hurt you in the slightest but I also don't think you should worry.

-Who did the mani? It looks mig welded, is it?
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Old 02-16-2007, 09:10 AM   #3
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FM and BEGi put relief cuts in their log manifolds, but they're also cast iron.
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Old 02-16-2007, 09:45 AM   #4
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So when to cut and when not to cut?????
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Old 02-16-2007, 09:50 AM   #5
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They also make their cuts through the bolt holes so that you can still get even pressure across the manifold. It looks like he would have a good deal of trouble trying to make the same diagonal cuts throught the bolts holes on this manifold.
If I was to make cuts in it, it would only be through the bolt hole, if you just make a random cut I think you will have a much greater chance of it leaking because you won't get it to seat properly against the gasket.
Like I said though, I've seen quite a few of these manifolds and no one has made any relief cuts.
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Old 02-16-2007, 10:07 AM   #6
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it wouldn't hurt to put one between #2 and #3
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Old 02-16-2007, 11:56 AM   #7
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My Mild Steel log doesn't have any relief cuts, I did make the holes larger from the center out, which is what corky recommeends in his first book. I also have never seen cuts in a steel log manifold.
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Old 02-16-2007, 12:45 PM   #8
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I've never made cuts in my manifolds and they have never cracked, but I figured I'd reweld them if they did crack.

I made the relief cuts in my greddy manifold and it did crack eventually. Go figure.
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Old 02-16-2007, 02:08 PM   #9
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The mani was tigged (atleast at the head flange for sure). I didn't think relief cuts were needed at all as it is all SS304 and I don't think it will expand too much thru its heats cycles, thanks for the insight guys.

The runners were welded by MXV on here, theres a thread about my dissapointment with how it was done, the head flange was done here, and my downpipe has a new flange at the turbo side as that was also a joke (not even the right flange lol)
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