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DIY exhaust - where can I buy flange plate?

Posted: Wed Apr 25, 2012 1:06 pm
by jimrat
Hi

I need to make a custom exhaust manifold to fit a m20b25 head (NA, not turbo).

Anyone know where can I source a flange plate from?

Also, should I use mild steel or stainless? I've got a welder set up for mild steel, but have read that stainless is easier to work with. Is that correct? Are there any disadvantages with stainless vs mild steel.

and finally, who's a good UK supplier of pipes, bends, silencers etc. Not looking for anything too bling, just good quality.

Thanks
Jim

Re: DIY exhaust - where can I buy flange plate?

Posted: Wed Apr 25, 2012 1:10 pm
by fowler
jetex is where you want to look for all bends etc
why make one when they can be bought ?

Posted: Thu Apr 26, 2012 12:23 pm
by jimrat
It's an M20 engine in a 1971 bmw 2002.

The steering box clashes with the standard 325i exhaust manifold, so the only option is a custom set up. Cant afford to get one made, so would like to go DIY route.

See some advertised on US sites - anyone know anywhere in the UK? Any help much appreciated

Cheers
Jim

Re:

Posted: Thu Apr 26, 2012 12:39 pm
by steve_k
Try fritz bits as I'm sure they can supply you with a manifold that will fit.

also as Ben states, for pipes, bends & anything else exhuast wise then got to jetex as it's fairly priced & pretty good quality.

Re:

Posted: Thu Apr 26, 2012 1:20 pm
by maggspower
I'm sure a guy called Turbo Brown on here has got some downloadable drawings/files so you could take it to someone with a water jet cutter I'll see if I can find them for you.

With regards to welding, for stainless you will need a gas that contains a high percentage of argon otherwise the weld will be rubish, pure co2 is no good. Nothing wrong with mild steel, I personaly prefere the sound of mild, but stainless has it advantages with corrosion. Whatever it needs to be a good thick gauge, as mentioned Jetex is a reputable outfit.

HTH

Re:

Posted: Thu Apr 26, 2012 1:27 pm
by maggspower

Re:

Posted: Sun Apr 29, 2012 1:45 pm
by HairyScreech
In the sizes and gauges used for manifolds mild is often a better choice as its hot mechanical properties are better. Hence why true motorsport exhaust jump from mild straight to inconel etc.

Have you considered doing a rack and pinnion conversion instead of making an exhaust?
It would probably be easier and result in a better car.

Re:

Posted: Mon Apr 30, 2012 8:17 am
by kam-325i
Mild steel is easier to work with.
Stainless has its anti corrosion properties, but you must use the right grade.....