Is there a tried and tested way to form round tube to match the oval exhaust port shape found on most modern engines?

There's some good advice on this in one of these 6 vids, but its well worth watching all of them.
https://www.youtube.com/watch?v=j9knDsi-td8

Cheers... will have a gander!

When I made manifolds for square ports I tacked the exhaust tube in place in one position on the manifold flange then shaped it by hand to match the rest of the contour. When I had a section of the port that matched well I then tacked it again and so worked my way round the rest.

You have to do some sums first to make sure the circumferences are the same. My pipe was slightly larger than this calc requires and I ground the inside to blend them.

When all the manifild was tacked I welded the seams.

Cheers!

I just used a vice on my stainless steel manifold and it worked VERY well. I was expecting it to pop a flat on or go wrong.

This is the part that gives some good ways of doing it.

https://www.youtube.com/watch?v=F-2SX7bUIlY&feature=player_detailpage#t=231

[Edited on 28-8-13 by loggyboy]

http://www.abperformance.co.uk/products.aspx?cat=19




Oval to round adaptors - a Woody job

Cheers fella's.. much to think about there!

As per someone above, I just squeeze it in a press and then fettle the inside slightly with a die grinder to get it spot on - I'm in there dressing the welds anyway so not really much extra work.