Making own exhaust??

[MatZZ]

Hi, basically im thinking of getting full stainless steel exhaust done for my m30 swapped e30. But as i have done everything in the car my self and i enjoy working on it im thinking of making my own 2,5inch twin pipe exhaust over the standard bit bodged and bolted on e30 exhaust thats on it now. It also doesnt look very nice atm.

I have access to a welder, grinder ect at home as im a mechanic.
Now does this sound like a silly thing to do ??

How could i make the bends without cutting straight pipe and re welding it on 10 times. if i had to do it im guessing that would create alot of restriction / make bad air flow and basically its a waste of time.? Could i buy the bends on ebay? Should i keep the e30 route of exhaust?

Any expert exhaust makers ?? Also how much would i be looking at in a recomended exhaust shop for a whole 2.5inch exhaust. Stainless and normal

Cheers

[HairyScreech]

It's really not worth the pain, been there, tried that, never doing it again.

Its good to make awkward custom bits you cannot buy but for things you can buy easily/cheaply its not worth it.

[JF008]

Hi MatZZ, I think I paid £400-500 for a custom twin 2.5'' s.s. system from the manifolds back.. I like the racy sound but there is a bit of drone drone when the engine is ''straining'' but full chat is awesome.
I should have gone to a single 3''ish pipe from the mid section to the backbox I think... Its an m50 engine mind you, m30 e30 owners will chime in hopefully and you could copy their design if any good.


Do you have a build thread?

JF

[steve_k]

if you are starting from the manifold/down pipes then you can get all the parts you need from jetex,

why not throw an X-pipe in there aswell??

i made my own system for my hartge 2.7 a few years ago, not had any problems with it either,
it can be done just takes time to get it right.

[MatZZ]

Cheers guys for the replies!

JF008 nope no build thread as there are many m30 ones didnt see the point of doing one :/ and im thinking of going minimum 2.5" twin as i will be trying to squeeze power out the old m30 lump, propbably f/i. And where abouts did you get that done? I got quoted 600-700 quid for ss. Its a bit of money especially as the conversion costed me very close to that including buying a six puck paddle clutch

Steve k and how much did it add up to you ??

Still not sure what exhaust size to go with for what i need

Cheers
Matt

[steve_k]

off the top of my head i think it was about £20 - £300 but it was nearly 5yr's ago.

[JF008]

I had mine done at http://www.classiccustomexhausts.co.uk/ in Hastings. I went from twin 3'' to twin 2.5'' and feel no difference on the butt dyno, sound quality is paramount for a road car IMO, I drove from Eastbourne to Land's end and back last summer with a non restricted twin 2.5'', I had baffles added when I got back

Good luck with the rest of your project, always nice to see other peoples car and work hence why I asked about a build thread, I read them all even and never finds it repetitive

[reggid]

twin 2.5" is fucken huge, are you guys blown or turboed?

[steve_k]

mine is twin 2" straight through to single back box with an X-pipe on the end of the down pipes,

nice deep V8'ish burble/rumble on idle rising to a bike like howl over 4K.

[HairyScreech]

As you say Reggid, 2.5" is huge.

Steve - think mine is the same ~50mm bore and that was sized with a tweaked 2.8 in mind.

A lot of the M5x cars are using the sportex exhaust which is what I am using now, the M30 is not going to move significantly more air than a 3L m5x.

[Lurch320i]

I made my own exhaust out of stainless, I just bought loads of straight pipe and a mixed box of bends
But I'm running a turbo so it's 3" from the turbo back





It drones a bit but I wanted free flowing for the turbo

[steve_k]

like i said if you are going from the end of the downpipes to the back box it's easy enough, just take your time,

word of wisdom, if you want to be on the safe side come mot time then wrap the whole thing in exhaust heat wrap, covers up & messy bits

[JF008]

As reggid said 2.5'' is huge! I've just used a converter and I went from twin 2.5'' to twin 2''

[reggid]

im running twin 2.25" and its still easily oversized. twin 2" is plenty or a single 2.5" unless you want to make over 300bhp in which case 3" is better especially if you need to run an aftermarket cat