DIY Exhaust

will01 · Apr 4, 2016

Hi Guys
This is mainly directed towards the 2.4JTD SW as i need to replace the backbox and will be making up my own straight through pipe.
However i also have a far few other cars which i need to make up exhausts for.

Does anyone know a good place to purchase bends and pipe from in stainless or mild steel, plus i am looking for weldable exhaust tips.
If mild steel i am happy to give it a shot with my current MIG setup, however with stainless i think i am right in thinking stainless welding wire should be used.

Has anyone had much luck making their own exhausts up?
Thanks

Pud237 · Apr 4, 2016

Birchills Automotive Exhaust Products - Custom Built Stainless Steel Exhausts, Endpipes, Beading, Exhaust Components, Tailpipes, Sports Box

No online shop, but if you register they will send you a catalogue.

You pretty much just need a straight bit of tube about 2ft long and a tailpipe if you don't want to reuse the one on your original backbox (which is what I've done). You won't need any bends as you can cut the straight pipe at an angle and build up the gaps with weld, then do the same with the tailpipe. I think its 2 and 1/8th inch on the 10v.

If you're welding stainless to mild, get some 309L wire.

will01 · Apr 4, 2016

Thanks Dan

I thought it would be a good post as i intend building my own exhaust with stainless for the Capri with Cobra V8

Maybe get some practice in with the SW haha
Unfortunately the tail pipe on my box has been pigeon poohed to the backbox and looks awlful, so i think a fresh exhaust tip make it look a bit cleaner

Pud237 · Apr 4, 2016

Oh yeah I remember now. Loads of nice tips available on ebay, even if they're designed to clamp on you could weld them on.

will01 · Apr 6, 2016

Thanks Dan, think i am going to have a look at ordering a 5kg reel or 309L and do some research into Gas. I currently use a 20% Argon/CO2 mix 40kg bottle. Just hoping that is ok. I also have 1kg CO2, but i think you need the Argon mix for stainless. C02 i think is only really good for Mild Steel. Could be wrong, but i like the Argon mix as it gives a better weld when doing car bodies etc.
Just checking out local suppliers to me for Stainless pipe now.

As i said its more of interest in stainless as i have several exhaust systems to make up for other cars we are building, so i may aswell get some practise. Unfortuantely i cannot TIG and don't have a TIG set, but i can live with MIG welded joins, just need to be careful to keep them well sealed

I have just remembered that i have most of the standard exhaust off a Mini Cooper S lying around, if thats the same diameter i will just use that for short term solution.

Gertie · Apr 6, 2016

For my 156 racer we built a downpipe with mild steel mandrill bends, arc welding and eyeballed all the cuts. It is doable :thumbs:

http://www.alfaowner.com/Forum/attachment.php?attachmentid=619146&d=1457690671

http://www.alfaowner.com/Forum/attachment.php?attachmentid=622386&d=1458468690

Ok we have the benefit of low probability of rust, thus mild steel is perfect for me, maybe stainless is your best answer

samsdads156jtd · Apr 6, 2016

I have done quite a few exhausts for various different cars over the years and generally use mild steel, mainly cause i dont have my own TIG setup, i had to leave mine behind when i left Rolls Royce. For bends i did own a small pipe bender but never quite managed to master it lol! So, I generally use Jetex for bends and joints etc as their prices aren't too bad and they do a good range of parts and tubes sizes including stainless steel and they have an online shop

For mig welding stainless you need a really high argon to co2 mix (97.5/2.5) or better still a tri-mix gas with argon/helium/co2 as this generally gives a flatter bead. Pure CO2 is for mig welding mild steel but i always found the argon mixes to give a better weld.

Just made a decat pipe for my 1.9 16v 156 diesel and have found the car a bit more responsive now and sounds better too

rob99 · Apr 6, 2016

Decat pre-cat is one of the better basic mods to do on the 1.9

Welding stainless a pure argon will be good but if you weld mild steel with it the weld will be brittle and no good.

Argon c02 mix is good for mild steel but if you weld stainless it leaves holes in the weld.

will01 · Apr 7, 2016

Nice, oh well it looks if i am to be serious then i need to look into yet more gas bottles. Seems a bit of faff, so i will keep it simpe to start and use mild steel.
I can't justify having more gas bottle on rental, even if i do only pay a trade price.

I need to get myself a TIG setup and practise and get some more training, then i may stainless in the future. Also means i could make up fuel tank for the Race Capri aswell haha

crossshot · Apr 7, 2016

Pud237 · Apr 9, 2016

will01 said:
Nice, oh well it looks if i am to be serious then i need to look into yet more gas bottles. Seems a bit of faff, so i will keep it simpe to start and use mild steel.
I can't justify having more gas bottle on rental, even if i do only pay a trade price.

I need to get myself a TIG setup and practise and get some more training, then i may stainless in the future. Also means i could make up fuel tank for the Race Capri aswell haha

You should try hobbyweld if you don't do a lot of welding. No rent on the bottles, but the deposits are high. But you get that back eventually when you hand the bottle back.

typos1 · Apr 9, 2016

Pud237 said:
You won't need any bends as you can cut the straight pipe at an angle and build up the gaps with weld, then do the same with the tailpipe. I think its 2 and 1/8th inch on the 10v.

Do you know the differnces in size between the 1.9 16v and the 2.4 10v and 20v downpipe diameter Pud ? I can only find conflicting info.

Pud237 · Apr 11, 2016

typos1 said:
Do you know the differnces in size between the 1.9 16v and the 2.4 10v and 20v downpipe diameter Pud ? I can only find conflicting info.

Not sure on the downpipes. On the 10v its a weird cast steel thing, not tubular at all. On the 1.9 16v and 2.4 20v they have cats in them. But they aren't the same fitment as each other, angles are all different so they can't be swapped over anyway. I seem to recall the front sections are bigger bore than the middle & rear, I think they go into the cat one size (1/8th inch) larger than they come out.

will01 · Apr 21, 2016

Birchills catalogue now arrived so will be looking at creating a small order to begin with. But i do have several other exhaust systems to make up so i will be on that alot more in future.
Probably going to look at ditching my current gas bottle in exchange for the Argon bottle. I can then MIG steel with that anyway. No point having 2 bottle rents to pay.

will01 · Apr 21, 2016

Pud237 said:
You should try hobbyweld if you don't do a lot of welding. No rent on the bottles, but the deposits are high. But you get that back eventually when you hand the bottle back.

Dan, i am doing alot of welding and got another E-Type to do alot of panel repalcement on. Rent bottles seem to work well for me with the medium size. I did look at hobby bottles as that is what we used to do, but now with soo many projects it doesn't add up.
Can't believe i have used 2 bottles on my Capri though! haha. But i only am welding in strut braces now and all other work is done(i hope).
After the E we then already have another old 1947 Riley which i want to crack on with and make into a sort of Goodwood type classic racer.
Not mentioning getting my subframes made up for my GSXR1100 powered Corsa

Gertie · Apr 21, 2016

Sounds like fun times :thumbs:

typos1 · Apr 22, 2016

Pud237 said:
Not sure on the downpipes. On the 10v its a weird cast steel thing, not tubular at all. On the 1.9 16v and 2.4 20v they have cats in them. But they aren't the same fitment as each other, angles are all different so they can't be swapped over anyway. I seem to recall the front sections are bigger bore than the middle & rear, I think they go into the cat one size (1/8th inch) larger than they come out.

The pre cats arent actually part of the downpipe, the down pipe bolts onto the pre cat, well at least on the 16v. Bigger, then reduces ?! Thats f*cked up, bad exhaust design !

Just wondered if the 2.4s were any bigger than the 1.9 16v. If they are, was thinking about modding one for a 16v. Its the bit that goes through the sump I was thinking might fit.

Pud237 · Apr 24, 2016

typos1 said:
The pre cats arent actually part of the downpipe, the down pipe bolts onto the pre cat, well at least on the 16v. Bigger, then reduces ?! Thats f*cked up, bad exhaust design !

Just wondered if the 2.4s were any bigger than the 1.9 16v. If they are, was thinking about modding one for a 16v. Its the bit that goes through the sump I was thinking might fit.

I usually refer to the bit that comes off the turbo as the downpipe and then the first horizontal piece of exhaust (which contains the flexi) as the front pipe. But we're talking about the same bit, and I think the 2.4 20v is a size larger even though the cat-back exhaust is the same size as the 16v. It'd probably need a bit of cutting/welding to get it connecting to the centre cat.

typos1 · Apr 24, 2016

Ah, I was calling the bit that bolts onto the pre cat and ends with the flexi the downpipe, but youre right, were talking about the same bit.

I was thinknig it would need modding to get it to fit the pre cat but that it would fit the centre cat ok, you think the other way round then ?

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