#132483, "exhaust manifold heat relief" Nov-29-10 05:45 PM by 420agreenvilleSC
I've found several threads on this topic, all good reading. They all address relief cuts and how they're good, but they don't answer a couple questions I have...
I have a star knockoff. It's a one piece solid CAST IRON design (no individual runners). This is the 2nd and last time i'll be surfacing and doing this. I'll be cutting reliefs, using antisieze on studs/nuts/lock washers, and copper silicone on the gasket.
1. Is there a reason why relief cuts are sometimes found along the middle of bolt holes rather than between runners? 2. Since my mani is one solid piece, does it really matter where the relief cuts actually are? (some are VERTICAL between the ports, others are DIAGONAL or some other way). In other words, does orientation matter?
most of you know what a hahn mani looks like but for reference...
Outside of Corona: "That sucks, peace out..." (jamie walks away)... "Sweeet, what we doin?" -Zac Tim's garage (prior to motor install): "Im gonna smoke real quick, that way if you fuck up I am already nicotined up" -Tim
#132484, "RE: exhaust manifold heat relief" In response to Reply # 0
I would assume that as long as there is room for expansion between the runners, the relief cuts will serve their purpose. I do not think that the orientation is as critical, but again I have not scientific data to back this up.
FWIW, I run a treadstone log without any cuts and I have not had any issues with blowing out the gasket yet.
#132486, "RE: exhaust manifold heat relief" In response to Reply # 1
I've been considering switching to that exact type of manifold from my Hahn so I can use an external wga, what's the hole on the t3 flange for? Or is that tapped for egt or something? I haven't seen that before.
#132487, "RE: exhaust manifold heat relief" In response to Reply # 2
Originally posted by Red90Sev I've been considering switching to that exact type of manifold from my Hahn so I can use an external wga, what's the hole on the t3 flange for? Or is that tapped for egt or something? I haven't seen that before.
Probably for his EGT probe.
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#132493, "RE: exhaust manifold heat relief" In response to Reply # 3
I have run a Star without Cuts and I run a 16" Tubular equal length without cuts and no issues of gasket leaks. Over time any flange will warp even the ones that are individual flanges for each pipe.
Outside of Corona: "That sucks, peace out..." (jamie walks away)... "Sweeet, what we doin?" -Zac Tim's garage (prior to motor install): "Im gonna smoke real quick, that way if you fuck up I am already nicotined up" -Tim
#132495, "RE: exhaust manifold heat relief" In response to Reply # 5
Originally posted by 420agreenvilleSC yes, that hole is threaded for the EGT probe. Ok, i understand, now, the final question, to cut or not to cut.... i'm seriously just debating on leaving it uncut and just getting it plained
#132546, "RE: exhaust manifold heat relief" In response to Reply # 6
Originally posted by teklein
Originally posted by 420agreenvilleSC yes, that hole is threaded for the EGT probe. Ok, i understand, now, the final question, to cut or not to cut.... i'm seriously just debating on leaving it uncut and just getting it plained
Yeah, you should definitely have it "plained".
Maybe even planed?
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#132547, "RE: exhaust manifold heat relief" In response to Reply # 7
Just put a 1/8 bead of high temp silicone on the gasket and install it. Make sure your tightening the nuts on the studs otherwise its never going to stop being a pain in the ass.
The superbee headers flanges are warped as most all are after 12 years of service and they seal with that method fine. Just putting them on with new gaskets they leak like a dirty snatch with the clap!
#132548, "RE: exhaust manifold heat relief" In response to Reply # 8
A good thick spraying with copper gasket spray works pretty well too.
Erik P. Official 2GNT thread Hijacker Some say that he's driven over more Covenant than he's shot, and that his grenades aren't where you'd expect them to be... All we know is, He's not The Stig... But he is The Stig's Spartan cousin!
Outside of Corona: "That sucks, peace out..." (jamie walks away)... "Sweeet, what we doin?" -Zac Tim's garage (prior to motor install): "Im gonna smoke real quick, that way if you fuck up I am already nicotined up" -Tim
#132575, "RE: exhaust manifold heat relief" In response to Reply # 5
No one has mentioned it yet, but the coeficient of thermal expansion for stainless steel is almost twice that of cast iron and steel. The HRC manifold is cast stainless steel (original HRC was welded from stainless steel parts). Reliefs would be helpful here. The Star manifold and knock-offs are cast iron. Reliefs are less important here.
