My car was used many years ago by Hayward & Scott to build the first 3" downpipe for the 20vt

I've used the car very hard ever since and the pipe has been faultless (apart from wearing through part of the flexi where it rubbed on the undertray, but that's hardly the downpipe's fault)

However, when Barbz delivered my freshly-ported cylinder head, he commented that the downpipe would be holding back my power, as it wasn't a true 3". Sure enough, on inspection, it's pretty obvious that it's tapering down to about 2.5" - 2.75" for the initial bend, then up to 3"

Its clearly not a massive restriction, otherwise I wouldn't have produced the power I've got, but Paul at Motormech is going to have a go at fabricating a true 3" downpipe, just to see if it can be done within the (very) tight confines of the Coupe engine bay. He's got hold of a 5-stud flange and a 3" downpipe from another car - this also has a very tight bend straight out of the turbo - he may be able to cut 'n' shut the pipe to fit the 20vt

I've seen the MIJ downpipes, but I have to say I'm not particularly impressed with the sharp angle that has been fabricated into the elbow.

Anyone got any suggestions or piccies?

nigel nigel you havent seen joes FCSS page have you with the true 3.5" down pipe on it and the external wastgate plumbed in.

its a work of art

I have a full 3.5" system including downpipe, but the space is so tight, the very first bend from the turbo is 3" widening to 3.5".

How did you manage to fit a full 3.5" bend in there?

from what i remember the oilcooler pipes where braided to make space

Can't find it...

Go to photos and look for it Nigel!!

Clicky Here you go Nigel

im sure it tappers down at the end to match up to the 3" that was already made for the car

By making major adaptions, but once done there's plenty of clearance.

http://www.fiatcoupeclub.org/forum/ubbthreads.php?ubb=showflat&Number=1388098#Post1388098

Give me a bell Nigel, impressive gains on spool up.

Just a thought....

Why down we extend the manifold downwards by say three inches, thus lowering the turbo) so that we can get a straighter exit from the turbo?

Should be possible with a pair of flanges and a short length of stainless tube

Would it cause more lag?

I looked at this but the turbo fails on the block casting for the balance shaft, moving it forward fouls the rad so larger turbos are limited for there position.

Makes sense - just wondered why it hadn't been tried before

Shame we can't move it a couple of inches to the nearside of the car, but I guess that would require an entire manifold - not worth it just to open out the initial bend

Paul has an idea he's going to look at next week - watch this space....

Nigel, I did mention to you that the Hayward downpipe wasn't a true 3" when you first had it done many moons ago. I don't know why they did that really, just a bit lazy perhaps, as it's not that hard to make a full 3" system without any modifications to the standard setup.



The 3.5" is a different kettle of fish, but there is room to be found.

Anyway, it is certainly worth doing, we need to see every last bit from that turbo of yours.

Just a thought but doesn't Paul do exhausts?
If so the components can be bought cheap and then its just the welding.
A downpipe won't cost you more than £70 in materials.

Agreed - I'm sure it has quite a bit more to give with the right supporting mods, especially in the areas of spoolup and mid-range

John - yes, Paul also runs a Longlife franchise, so we have access to everything we need to make a one-off. My exhaust from the downpipe back is a one-off 3" system built by Paul

The hardest bit is the first foot or so - getting cleanly out of the turbo and turning sharply downwards, without restricting flow or touching the oil cooler pipes.

I'm just searching for some heat-wrap - I think I'm going to need it this time

Yeah the first few inches is difficult.
I made 1 inch segments and welded them on that way.
Made it also easier to tig weld them as tig is less forgiving if you have gaps.

The first foot had around 9 segments on mine.


Made life easier to Tac them and then machine the weld off from the inside to promote the flow.
Took me 4 days to make mine,but around 6 hours to make the downpipe.

But I had the joys of trying to squeeze a 4" exhaust in so won't take you as long.

Great satisfaction to see it built at the end.
And further to that saving yourself a few quid for a better job is always worth it.
Paul will love doing that

have you got any pics of yours JBT would be good to see in comparison with the other's on the market, i was thinking of lobster backing mine and i still think it will be the best option.

Copyrighted I'm afraid.
Only Barbz,Biggenz's and crazylegs have seen it
And it's covered in heat wrap .
2mm clearance each side of the sump.

Front section upto the handbrake cables looks a work of art.
Chocolate orange comes to mind .
The back half is scruffy as I lashed it together as I was getting peed off with welding and fabrication on the 4th day and needed it done for mapping.
My face was burned,my hands were torn and my head ached.

Trying to et 4"components was no mean feat.
Had to use truck exhaust.

But as Ed China would say.
Probably saved myself £600 in expensive garage costs.

But....you had a nice tan.

Yeah only problem is it started peeling the next day which made me look like i had some sort if skin disease.

Never a good look.

Who, JBT? You're not wrong lol

Dude I looked like Mattm

Your taking a pasting tonight jbt.
Everyone is having a dig. Cough cough (power envy) cough.

I dish it out enough,so its due returned.

As proctard says,if you want to give then you must be prepared to receive.

At least that's what his man friend says

It's lukcy i read the whole of JBT's post otherwise i might have gotten the wrong idea

copyright