Cast iron vs. stainless steel
Turbo Mini Forums

Hi.
I am thinking about Building a Cast iron exhaust manifold from a standard mini single downpipe as an alternative to the Log type (mirage) manifold.

Is it a good idea ? Will it retain heat better ? Or is it not worth the trouble?

I would like your opinion.

Thanks in advance

If i have more toys than you when i die, I WIN

pretty sure the manifolds are cast steel rather than iron, but if they are iron it will be a pain to work with and prone to cracking

Some cast iron can be tricky to weld, others weld really easy.

All you can do is try, but yes if the fitment works for you, give it a go. They're certainly cheap...usually free, so why not ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I've seen many "budget" turbo manifolds where a steel flange was welded to a cast manifold. One I saw a few months ago was on a SBC twin setup. It looked like absolute crap (apart from the very shiny turbochargers - I think that was par of the "look" but wow it was quick!
As Stevie says, you'll know as soon as you try it whether it's a suitable cast steel or an unusable brittle iron. Probably just doing a hammer test to determine the ductility of the manifold you're proposing will show if this is do-able (brittle is almost always more difficult to weld). Pre-heating is definately something to do though.

I think the standard manifolds are cast iron. In my autograss days I broke the end off a few of them!

Thanks lads.
I think i will have a go at it with some preheating/postheating and hammering on the welding

If i have more toys than you when i die, I WIN