A few people on my local forum state that a manifold (na or fi) should never be made of stainless as it is prone to cracking through heat disapation and expansion.
Any grade stainless.
Any thickness.

They also state ss manifolds always need bracing for the turbo.

I see quite a few people on here making their manifolds out of stainless. I myself have a stainless header.

Are they talking bollocks?

 

They really are speaking hogwash and rumors....

Stainless turbo headers have been known to crack due to excessive weight placed on the tube pack. So lets walk through this here: you have 30 pounds + of weight (i think thats roughly what turbos weigh?) and then you have 1500 degree's egt's depending on a number of factors, add into that vibration coming from the engine, coupled with stainless natural tendency to grow and you have a recipe for cracking.

Here is how you can prevent it: you can use a single or double slip collector so the manifold can contract and expand, you should fabricate a brace so the header does not have to support the weight of the turbo ( a header is not a device designed to hold weight it is designed to promote scavenging and exhaust spent gases from the cylinders, so don't use it as a weight support) The brace should support the weight of the turbo yet allot the turbo to move freely so it does not grow into itself and induce failure.

You can also use a turbo header like Full-Race sell thats is made of a thick cast stainless this will help solve some of those issues as well.

I hope this helps clear up some of the nonsense you were exposed too!

 

 

Cheers mate.