how bad can the exauhst manifold be cracked without affecting performance?
Thread Starter
Senior Member
Joined: May 2004
Posts: 386
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From: chicago
how bad can the exauhst manifold be cracked without affecting performance?
just wanted to know when cracks in the manifold start to affect the performance of the stock twins. is some minor cracking still ok? i know eventually it will lead to disaster, but how long? anybody's experience would be nice...
It's normal and not a big deal. I don't know what ^ is talking about.
When the cracks extend past the edges of the metal gaskets, or your boost pattern is affected, then replace them.
Dave
When the cracks extend past the edges of the metal gaskets, or your boost pattern is affected, then replace them.
Dave
Trying not to be stock
Joined: Jan 2005
Posts: 374
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From: Richmond, VA
sorry, i just wouldn't run it hard at all if there was any crack in mine. I'd find a way to patch it up...then we'd talk. I just get the feeling that if he's asking, he's still running it hard.
Originally Posted by RevZempoe
sorry, i just wouldn't run it hard at all if there was any crack in mine. I'd find a way to patch it up...then we'd talk. I just get the feeling that if he's asking, he's still running it hard.
https://www.rx7club.com/showthread.p...manifold+crack
https://www.rx7club.com/showthread.p...43#post2450643
https://www.rx7club.com/showthread.p...manifold+crack
It won't hurt anything to run them until you have the budget for the new ones.
Dave
https://www.rx7club.com/showthread.p...43#post2450643
https://www.rx7club.com/showthread.p...manifold+crack
It won't hurt anything to run them until you have the budget for the new ones.
Dave
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Exhaust gasses don't care in the least how the manifold *looks* - remember, we're talking about something we're seeing. You have to look at "will this keep the part from working like it should".
Cracks that creep into gasket mating surfaces are bad - they can blow out the gasket over time, causing an annoying exhaust leak. Cracking around the wastegate ports are OK as long as it's not causing too big of a leak around the wastegate flap for you to lose exhaust pressure going into the turbo, as it's being bled off by the crack.
The worst-case would be cracks that cause a chunk of the manifold to break off. I have NEVER heard of this happening, though - somebody would have likely documented it if that was a possibility.
Again, remember that exhaust gasses don't care what something *looks* like. You can have a helluva lot of cracking and not lose any performance of the part. We see something that's broken and ugly, and assume it to be a bad, failed part, when it might be working just fine.
Dale
Cracks that creep into gasket mating surfaces are bad - they can blow out the gasket over time, causing an annoying exhaust leak. Cracking around the wastegate ports are OK as long as it's not causing too big of a leak around the wastegate flap for you to lose exhaust pressure going into the turbo, as it's being bled off by the crack.
The worst-case would be cracks that cause a chunk of the manifold to break off. I have NEVER heard of this happening, though - somebody would have likely documented it if that was a possibility.
Again, remember that exhaust gasses don't care what something *looks* like. You can have a helluva lot of cracking and not lose any performance of the part. We see something that's broken and ugly, and assume it to be a bad, failed part, when it might be working just fine.
Dale
They have to be pretty big and extend out towards the end of the gasket to affect performance. Manifold and wastegate cracks are very common, even on low milage turbos/manifolds.
Jack
Jack
