Stainless exhaust manifolds

[Fez887]

So looks like my S2 exhaust manifolds have got a few things in common with a tea bag! :smile: LHS being the worse. Despite the obvious benefits for changing them to stainless, will this make any difference to engine sound over and above the original?

[v8s4me]

Probably not. It's generally the bore of the pipes and what's in the "silencer" that makes a difference.

[Fez887]

Ok thanks, there is suggestion that stainless manifolds alter engine note. So it’s purely longevity with regards to material benefit?

[v8s4me]

Well they may make some difference but it's the rest of the system that makes more of a change.

[RayTVR]

Did the bolts come out ok?

[phillpot]

I suspect the harmonics of stainless steel are somewhat different to rusty mild steel but the fact the new ones aren't full of holes will make the biggest difference

[Fez887]

Yes surprisingly! I was warned they might not. As far as I know they are the original with original manifold so real bonus. I have already ordered the new gaskets but as we all know stainless manifolds are very pricey but may have a excellent welder friend who believes he could reproduce using old ones as a template. Would be nice to do in stainless but just trying to figure out all the benefits apart from longevity and looking pretty, before committing to expense.

[88S1]

There’s a LH side one on you know where at the moment.

[v8s4me]

If your mate can make mild steel ones for sensible money then go with those. If you want them to look pretty you could get them coated with something like CermaKrome. Stainless discolours with heat whereas ceramic coatings will stay shiney. Not cheap though.
I went for stainless but if was doing it again I'd opt for coated mild steel.

[88S1]

https://www.actproducts.co.uk/product/ms08-s-serie...

[phillpot]

Fez887 said:

Would be nice to do in stainless but just trying to figure out all the benefits apart from longevity and looking pretty.

They don't look pretty for very long without a lot of hard work!

An S3c I bought and sold had full stainless system, the flanges onto the heads had gone rusty, mild steel? Seen this on one or two other cars

[GreenV8S]

phillpot said:

They don't look pretty for very long without a lot of hard work!

An S3c I bought and sold had full stainless system, the flanges onto the heads had gone rusty, mild steel? Seen this on one or two other cars

Even 'stainless' manifolds usually aren't usually very stainless, and I wonder whether that's to avoid brittle failures - there can be high thermal stresses around the collectors.

[frontfloater]

I bought a set of stainless manifolds and downpipes from RT Racing (RIP Richard) in 2002. My local engineer who fitted them said that they were an excellent and easy fit. The fact that they are still on my car and serviceable 18 years later speaks for the longevity of stainless - it's a good investment. And my exhaust is a factory stainless item fitted in 1997. The mileage has been relatively low (30,000 in 23 years) but nevertheless, how many steel ones would have rusted out over that period ... ?