Custom Exhaust Manifold is cracked / has hole... what could have caused this? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 03-01-2009, 08:14 PM   #21
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I welded the crack up, despite how I kept going right through it... it really is thin metal. I ran a few thicks beads across it hoping to give it a little more structure... I only want it to last a few more thousand miles... we will see.
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Old 03-01-2009, 08:37 PM   #22
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That is the only crack you have. LOL

Mine is about to fall apart! LOL!
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Old 02-24-2010, 07:51 PM   #23
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Unfortunately having issues with my new exhaust manifold and looking for some advice/tips on the support braces i'm about to make. I dont want to mount to the valve cover bolts so mounting locations are limited... but welding is an option.

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This is the new manifold Ive been using.

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Downpipe to transmission bracket. I will defintiely use this.

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or

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Old 02-24-2010, 09:21 PM   #24
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Other than the fact that it is a cheap POS manifold to begin with, the heat wrap was probably a contributing factor. It allows moisture to get trapped next to the manifold, which can create large temperature gradients between nearby sections of metal, which leads to stress cracking.
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Old 02-24-2010, 09:32 PM   #25
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you cant brace it off the head, there will be dramatic differences in thermal expansion and it will cause another failure.

If that is thick material you wont need any bracing, that looks like a JGS to me, so that means its basically made of weld-els and should be plenty strong.
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Old 02-24-2010, 10:34 PM   #26
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Quote:
Originally Posted by Full_Tilt_Boogie View Post
you cant brace it off the head, there will be dramatic differences in thermal expansion and it will cause another failure.

If that is thick material you wont need any bracing, that looks like a JGS to me, so that means its basically made of weld-els and should be plenty strong.
It is a JGS (stage 2 i believe) and is way thicker than my first. Lasted 2k street miles. If I cant brace to the head, is their anywhere safe I can brace to? The standard issue bracing from downpipe to transmission just isnt cutting it.

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Old 02-24-2010, 11:04 PM   #27
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I don't see the new manifold being a problem...
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Old 02-24-2010, 11:07 PM   #28
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If that's a JGS mani, you won't need to brace it. It's sched 40 pipe, plenty strong.
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Old 02-24-2010, 11:11 PM   #29
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leave it to the brain to crack a jgs log.

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Old 02-24-2010, 11:36 PM   #30
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Thats what my new cracks look like.. no actual pics as its still on the car. Does the dead center location mean anything? High egt?
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Old 02-25-2010, 01:02 AM   #31
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hey look at that, cracked in the same spot...but my turbo sat directly off #2. Mine cracked from too much exhaust bracing, I had my DP mounted firmly to the tranny.
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Old 02-25-2010, 01:32 AM   #32
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Brace turbo mani to downpipe trans brace. Weld a tab to both the manifold and downpipe and bolt a fitted DIY steel bracket to it. I have had an ebay manifold and I was able to extend the life by doing this after it cracked a couple of times, along with an extra tab and bracket to the car's body, with swivel joints of course.

Edit: this may only work for my top mount, I forgot yours is a log... my bad. Brace downpipe to the block, where the tranny bolts to.
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Old 02-25-2010, 01:46 AM   #33
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good idea!

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Old 02-25-2010, 04:23 AM   #34
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Do you have a flex joint in you downpipe?
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Old 02-25-2010, 09:31 AM   #35
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Quote:
Originally Posted by Braineack View Post
hey look at that, cracked in the same spot...but my turbo sat directly off #2. Mine cracked from too much exhaust bracing, I had my DP mounted firmly to the tranny.
To much bracing!?!? Didnt think that was possible. What did you do then?

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Do you have a flex joint in you downpipe?
Yes.
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Old 02-25-2010, 09:33 AM   #36
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Quote:
Originally Posted by wrxnova View Post
To much bracing!?!? Didnt think that was possible. What did you do then?
Got BEGi parts.

Read through this, Keith explains the issue pretty well: https://www.miataturbo.net/forum/t43572/
(Post #9)
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Old 02-25-2010, 09:50 AM   #37
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Quote:
Originally Posted by Braineack View Post
Got BEGi parts.

Read through this, Keith explains the issue pretty well: https://www.miataturbo.net/forum/t43572/
(Post #9)
Im pretty sure my downpipe is to far from the transmission to use FM's brace (already considered it) but ill check it out tonight.
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Old 02-25-2010, 10:11 AM   #38
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A crack like that in a sched 40 pipe mani looks like the need for flange cuts. That said, the weld looks like it lacked penetration based on the rather large ridge. And I'd expect the load oriented crack to be in a weld running the opposite direction, like at the head flange or turbine flange- perpendicular to the load action.
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Old 02-26-2010, 08:11 PM   #39
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OT but are there any reports of the ebay T3 cast manifold cracking? I haven't heard any yet.
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Old 02-27-2010, 04:29 AM   #40
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Quote:
Originally Posted by Braineack View Post
good idea!

holy roflshits!! time to grind that **** off...
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