M3 S54 exhaust manifolds for ZHP M54

Something like that should of been on the ZHP to begin with. Great progress! The other folks with e46s in your class are going to be jealous!

Can't wait to see how this turns out. Great work

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Originally Posted by GoGators

Encountered the first significant snafu when I went to tack weld the flange to the pipes with the SS mig wire. It reacted poorly to the flange which based on the minimal corrosion I thought was a low grade SS bar. turns out its very magnetic, so it must just be mild steel, hence the SS wire wouldn't bond well. the pipes are definitely SS. So I have a dissimilar metal issue...

this fact may negate any benefit I would get by having some TIG weld it... so, i reloaded my MIG with the mild steel wire and tacked the flange to the tubes. going to consult the TIG welder i was going to use... downside of MIG with the mild steel wire is that it will corrode to some degree and more importantly, the filler material in the wire tends to create very hard, potentially brittle welds...

Attachment 25663

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I've had a few exhaust components over the years that were SS that had been mig welded. One I did myself. There will be corrosion for sure. They will get rusty, but they are under the hood so it wont be an eye sore. Only once did I have a weld crack, and it was on a knock off exhaust for my BRZ. Should be ok with the MIG i think.

Keep the updates coming! I am planning my exhaust set up now and want the Vibrant muffler but with catless headers, every cop in Irvine could here me get into town :eeps

Those look great. Wish they were more of a direct replacement! Would probably be a pretty popular "OEM upgrade" for us M54 guys if so.

Can't wait to see everything all bolted up. :)

Yesterday, James of street hero customs here in Jacksonville TIG'ed the interior circumference. Obviously, due to the tight interior and vast difference in material thickness, as well as one being stainless and the other carbon steel, it was a challenging job. the result is a nice bead all the way around, that was done in short stiches, this will be the only full seal as the entire external circumference is not accessible... more to follow!
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when I got them home, I did as much of the outer circumference as was accessible with my MIG. again, doing about 1/2" stitch welds. they aint art, but they should be functional!

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with all the fabricating done I wanted to test the setup.... its an understatement to say that finding a leak after installation would be inconvenient.. pic of test rig:

Attachment 25785

video of ~15 psi air test. both passed. my largest concern was actually the upper O2 bungs, I had to cut ~15 mm off of them. then file it flat, which is the sealing surface...
https://youtu.be/bm-l02Ggr1Q

finished product compared to the ZHP manifolds.

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all that's left is the simple chore of installing (haahaahahaa) then mating up the muffler delete 325i exhaust I previously put together with output flange of the M3 headers using a donor M3 section 1 pipe set...