Manifold Tube??

8th November 2006, 08:18

Hi.

Im just about to order some seamless steel to make a manifold for my turbo, but what diameter should i use?

The wall thickness is going to be 2.5mm.

If This all works out (which it will), then i will me making custom manifolds.

I have been told to use 40mm, but with a wall thickness of 2.5, that only leaves you with a internal diameter of 35mm!!?? Thats never big enough is it?

8th November 2006, 09:24

should be ok dont think 5mm will make much diff im going to make 1 for mine soon too and get things rolling i was gonna use the standard manifodl and make an adapter flange but im gonna give it a crack

what are you using to mount the manifold to the head have you made a flange or got 1 made?
and how much was it?

8th November 2006, 19:06

What i was planning was to bolt the standard manifold on to the head, and cut the standard tubes off (so just leaving the standard flange). I will have a modifyed head, so at this point i will use a dremal type tool (not a dremal tho, they suck) and "bore" out the manifold flange to mate the head's new ports.

As my manifold is for a turbo, the manifold tubes will me off set (just like the cituning one).

The 1st tube i will bend is the smaller one (on the right of the head, as you look at the engine bay), as it would be a mission to fit it behind the other 3.

I already have a flange for my turbo, so i will tack weld it on to the head flange, and the top right corner of the turbo flange as you look down on it in the engine bay.

The 2nd one will be the next one to the 1st one. Which will be bent and tacked in place. It will go on the top left of the turbo flange.

The 3rd one will, again, next to the last one. Which will be tacked onto the turbo flange on the bottom left. (dont forget to bend this tube so the last one can go over it).

And the last tube you do it the one on the far left, which needs to be bent to the right shape, and tacked on to the turbo flange on the bottom right.
This will be the hardest tube to bend as you dont want it to rub the other tubes or the bonnet.

After each tube, check you can close the bonnet!

Once you have done all that, weld it up, and remove it from the head.
Take it to an engineering place and ask them to face/skim the flanges flat.
This is so you can get a good gas tight fit with the right gasket.

God im good!

8th November 2006, 19:19

I forgot to say, im using seamless mild steel as stainless is more likly to crack.

If you dont want it to rust, then get it sandblasted, and then dry it right out with a paint stripper gun, of if you dont have one, use a hair dryer but for longer.

Then spray it with heat proof paint (i got a 500ml spray can in black from halfords for about £4.99).

If you wana make a really good job, then heat wrap it (and use stainless cable ties, which you can get from most good electrical stores, so not homebase!).