Hi All,

I'm treading a well-worn path from crossflow to zetec. As part of that, i'll need a new exhaust manifold.

I'd prefer a 'over the chassis rail' type manifold, because that's the route the current setup takes and changing will mean new holes and probably moving the fuse box.

I've been looking into exhaust design, and it seems that making my own would be a possibility. I'm thinking a 4-1 for simplicity, with circa 32" primaries of 1.75" diameter, with a downpipe of 2.25 or 2.5". What I can't seem to find much about is the recommended gauge of steel I should use for the manifold. Does anyone have any recommendations? My plan is for mild steel - I'll design it then tack it together and have a friend welt it up. I know stainless would be nicer, but it's more expensive, I can't weld stainless and the rest of the system that it will plug into will be mild steel anyway.

There are plenty of sites out there where I can buy ready-made or custom angle bends, but what would be nicest would be a set ofprimaries bent and cut to my measurements - that would avoid joining multiple bends together. Anyone know of anyone offering that type of service?

Cheers
Matt

Went x-flow to Zetec in about 2002. Did quite a bit of investigations about exhausts and the consensus was 1.75" primaries into a 2.25" main system was good for over 225 bhp.

Mine was a 4-1 since at the time vary few were actually suggesting a 4-2-1 for a Zetec. Suppose it was difficult to understand since the other main popular engine at the time, the VX redtop, always seemed to be fitted with 4-2-1 manifolds. But I guess Raceline and Dunnell must know a thing or two.

With regards to the length of the primaries I am sure mine are either 26" or 28" which increases by a couple of inches if you include the distance to the back of the exhaust valve. Whatever they are its worked perfectly with 5 specs of engine, a bog standard silvertop on 45's and Jenvy bodies, a Silvertop with cams on 45's, a well modified 2.1 with a stage 2 head, cams and Jenveys and currently a bog standard Blacktop.

This is how it looked when first fitted on the current Blacktop, not so nice now.

one still for sale here (my old one)

http://www.locostbuilders.co.uk/viewthread.php?tid=196086

http://stores.spencerashley.com/manifold-kits/

Have a look on there they have kits for seven type vehicles if you are handy with a welder.

I bought a flange from kit spares then cut and bent my xflow manifold to fit the new flange
That was 2 years ago and it's still going strong👍👍👍
£15 for the flange and £10 for the local machine shop to TIG it up😃

4-2-1 will years greater torque.

Your old one has gone Dave i just forgot to update the thread!