can you use a mild steel flange for a ss manifold?
i would buy a jgstools flange but would rather have a stainless flange. so where can i buy a stainless flange?? for 1.8l (99 head) i am paying big money for the custom top mount setup for my tube front end rocket. i want to have as many parts for fabrication as i can to lessen the cost

 

M-tuned 1.8 Stainless exhaust flange, $85: M-Tuned Mazda BP (1.8 Miata) Exhaust Manifold Flange M-Tuned

 

thank you so much!!!

 

i know this is an old thread. bite me.

butttt i cant find it on that link joe provided. can you please post a direct link of it? thanks

 

You can find 1/2 inch stainless exhaust flanges for sale on my website in my signature, or pm me

 

try this http://www.jgsturbo.com/emf.html

 

hot damn. i will buy yours when the time comes! thanks for the heads up!
id prefer a stainless one over a mild steel one.

 

Awesome thanks!

 

now another question. still somewhat on topic:


is there a thread here that explains the different type of exhaust manifolds, and what it does to a turbo. like which one spools faster? which more is more efficient overall? heat retention? etc. ive seen a few differnt log manis (although i dont care about those) and a good amt of differnt tubular manis (what im looking for)


thanks.

 

The idea behind a long runner top mount manifold is that it causes the gasses to move at a very high velocity, where as something with shorter or larger runners may flow more it will not necessarily spool the turbo as fast or make as much peak power. In my opinion the idea is to build something that flows well but retains velocity, much like absurdflow has done.

 

You dont want a stainless steel flange, you want a mild steel flange (that goes for the turbo flange too). Stainless has a higher rate of expansion under heat than mild does which can result in more warping/leaks. Just use some 316ss filler rod to weld the stainless runners to mild flange.

Full race has some pretty good technical reading comparing different manifold designs with legitimate dyno testing.
http://www.full-race.com/

 

With either mild or stainless, you are going to have enough warping to necessitate decking the flange after welding. Once the flange is flat (either mild or stainless) and bolted to the head, it wont warp. So you can decide if a little bit more warping that you are going to flatten is worth having non-rusting flanges.

If you use mild flanges, they will eventually rust and look ugly.

 

Not in my experience. I warped cast manifolds severely with multiple deckings, and my AF manifold once.

 

Sir hustler your amazing badassness has proved my statement wrong. But by doing so you have also proved me right, by saying that cast manifolds have warped too.

Bottom line is, if its gonna warp, its gonna warp.

P.S. im pretty sure savingtons af mani has been warp free. What are you doing wrong, or is the e85 nicer to his manifold? From your other threads it also seems you might have an egt problem?

 

The linear coefficient of expansion for mild steel is 0.0000073in/in/degree F,
304 stainless is 0.0000096in/in/degree F. Of course you would resurface the flange after welding but stainless is still more prone to deformation with repeated heat cycling.