Hemi Exhaust Manifold New Design?

[Black1500Ram]

Could just replace the hardware preemptively with arp stuff and remflex gaskets.

 

[HEMIMANN]

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Too late!

 

[HEMIMANN]

Could just replace the hardware preemptively with arp stuff and remflex gaskets.

Not sure that would hold warped cast iron - the bolts aren't designed for clamp loads from permanently bent metal from the original position.

 

[Black1500Ram]

Not sure that would hold warped cast iron - the bolts aren't designed for clamp loads from permanently bent metal from the original position.

Agreed but didn’t you say yours are in pristine condition? I’ve seen a few threads on here of people just replacing the bolts and gaskets and calling it a day (with warped headers).

I know not the ideal solution.

 

[HEMIMANN]

Agreed but didn’t you say yours are in pristine condition? I’ve seen a few threads on here of people just replacing the bolts and gaskets and calling it a day (with warped headers).

I know not the ideal solution.

Yes. Swapping fasteners doesn't change the clamp loading. Bent manifolds do. At one time I was expert at cyclic bolted joint design at Cummins. Joints are designed for small thermal deflection. If the part warps and the bolt didn't break, i.e. if the bolt takes higher stress than the part, the part will break instead.

The manifold must be designed for acceptable small thermal deflection, and these were not.

 

[turkeybird56]

Too late!

Order for Next Year, Pre-emptive MX, lol.

 

[HEMIMANN]

The shop uses Remflex and ARP routinely. Another indication of quality work. I'm just miffed about the whole thing, including the failure mode itself. If I was younger and in better shape, I'd pull 'em myself.

 

[Tach_tech]

The updated manifold design uses extra braces across the top and bottom bolts. for the most part bolts don‘t break anymore but now the manifolds crack. so it’s fixed one problem but created another.

 

[HEMIMANN]

The updated manifold design uses extra braces across the top and bottom bolts. for the most part bolts don‘t break anymore but now the manifolds crack. so it’s fixed one problem but created another.

Thanks so much for weighing in, @Tach_tech ! If fact, the exhaust shop mentioned that Gen V Ram manifolds were cracking!

Just goes to show that there was insufficient finite element computer modeling done on the manifold for the thermal cyclic stresses involved. I'd be demoted or fired for that kind of insufficient design! There is insufficient material to distribute the stress within the manifold itself so a stress raiser is not created.

Oh, well - thanks again. Still not installing long tube headers, since there are none with EPA cats and they cost too damn much, esp with inflation (were $1,800 now $2,200)

 

[Black1500Ram]

Thanks so much for weighing in, @Tach_tech ! If fact, the exhaust shop mentioned that Gen V Ram manifolds were cracking!

Just goes to show that there was insufficient finite element computer modeling done on the manifold for the thermal cyclic stresses involved. I'd be demoted or fired for that kind of insufficient design! There is insufficient material to distribute the stress within the manifold itself so a stress raiser is not created.

Oh, well - thanks again. Still not installing long tube headers, since there are none with EPA cats and they cost too damn much, esp with inflation (were $1,800 now $2,200)

You could look out for some used shorties there are some deals to be had.