Question for you who have fabricated your own exhaust manifolds.
 

Guys, I'm going to be making or commissioning a set of turbo manifolds (single/split). I have long thought I would use stainless but I also plan on having the piece HPC treated inside and outside.

Is there any advantage to using stainless if it's coated or can I just go with mild steel?

Thanks for your input!

i made mine stainless, but go with mild steel

Stainless has a disadvantage of expanding more. This could cause stress cracks.

Use mild steel, I have built a few turbo manifold/headers for a couple of non MB cars. I used mild steel ells and primaries with milled barstock plate for the mountings. Very nice and easy to work with. Just make sure you get quality stock.

Will you be driving it on salted roads in the winter? If no, mild steel with properly cured high-temp paint will be ok

Thanks for the input. It'll be a turbo manifold so it also has to support the weight of a 30# turbo. I plan on having it HPC coated so corrosion won't be an issue.

I just see so many beautiful stainless manifolds and I'm just wondering what the big advantage is besides corrosion resistance.

Stainless is better at holding the heat in than mild steel. Coated steel is better than stainless. Coated stainless is better yet. Then you can buy inconel for who knows how much. Cost wise mild steel with a a coating is the way to go. The strength is not an issue if you use 16gauge.

The materials for my mild steel manifold cost $105, 2 2" schedule 40 L's, 4 2" schedule 40 T's, turbo flange and riser plate. Stainless would have been closer to 170-200. If its coated your all set, mine isnt coated but its a daily driver so rust isn't an issue.

TE320, where'd you get your materials? All I can find so far is heavy stainless. I'll be coating for sure for heat protection of the metal, better spooling time and protection of the stuff under the hood. Half of the header goes up and the other half goes down so it's close to a few melt-able things... :eek:

Where's a good source for the ells and T-3 flanges?

I seriously just went and found a phone book and looked up plumbing supply stores. In louisville kentucky I found a place called Plumbers Supply and they had everything I needed. If you get mild steel make sure its schedule 40 if you get stainless get schedule 10.

I got my flange from a local auto tuning/fabrication shop. I would have gone to ebay but I was told of the auto place beforehand.

EDIT: That local shop gets their weld l's and t's from the same Plumbers Supply.

what engine is this for?

For my OM606. There's more discussion on the Diesel performance page but this is general performance stuff and I wanted to tap into the expertise here.

This is a concept design:

http://i3.photobucket.com/albums/y71...stmanifold.jpg

The flange won't be splitting into 4 and 2 as shown, it's two sets of 3.