Hi all, I am wanting to make my own exhaust sytem for my non-turbo car. The system will most probably be made from stainless steel and I was hopeing to use 1.6mm wall thicknes. Do you think that this will be thick enough for hte headers? I am well aware that the rotor runs hot exhaust gas temps so do you think it will be ok or too think?
cheers, michael.
Racing beat headers use a mild steel "pipe" with a 0.125" wall ... thats 3.175mm in real measurements ;) I\'m not sure what will cause a thinner wall to fail, whether it is a corrosion problem, or if the temperature means that the strength of the material is reduced that much that such a thick wall is required ?
A decent grade of stainless should help with both anyhow, as it is more corrosion resistant AND it is a little stronger that carbon steel at higher temps.
Somthing tells me that the years of experience racing beat have with rotaries would suggest that 3mm might be a sensible wall thickness though?
hmmm, cheers mike. I was wanting to run the primaries to just before the diff then merg into a single 3 inch pipe over the diff. Running only one hotdog type silencer just before the diff then a larger muffler at the rear. So I wonder for how long the tube should be 3mm thick? Say about 1 meter long, then down to the thinner 1.6mm.
cheers, michael.
Hi bob,
If you have a spare 12A header, cut the pipes close to the flange and send items to your local blacksmith.
I am sure that they can custom bent to match your 12A pipes.
The metal is 2\'\' black steam pipe and the thickness is 1/8\'\', suitable for primary but it\'s heavy.
I remember, way back in mid 90\'s,I made one a header and blazed weld the pipes into flanges, got a shock when the engine went steaming loud.
The heat of the exhaust had caused the blaze to melt and the pipes dropped off. :2eek
Go for mig/stick weld, not brassblazing.
Hope it\'s a help !
I think the issue which sizes the wall thickness will be fatigue rather than anything thermal. 1.6mm sounds pretty thin, I suspect it will crack sooner rather than later :(
fatigue ? due to what loading ? Thermal fatigue maybe but not mechanical surely, otherwise all tubular manifolds would need to be this thick and i\'m sure most piston engine ones are not. Increasing the wall thickness could make thermal stresses worse
1.6 mm is to thin ,,,ask me....the headers deteriate at such a rapid rate you cannot believe it.Thinner the metal tends to \'flake off\' after a while,this is due to the heat of the exhaust gasses.Soon the wall thickness is less than 1mm.The old header on the 2 was so thin that when you start her up you can almost \'see\' the hot gassess inside !!!!!!!! You end up with glowing headers and all kinds of probs.Go for the 3mm + thickness and spare youself a lot of work later......
so it\'s corrosion thats the cause of the failures on thinner walled stuff ? I guess the thicker stuff just lasts longer ?
Would a more corrosion resistant material buy you as much time with a thinner wall ? Somthing like a Nimonic ? (I suppose it\'d be a lot cheaper to go with the thick stuff!!)
Good grade stainless is the answer for headers if you cannot replace them at will,if you have the ability or resources to replace frequently then evn mild stelel 3mm or 2.5 mm is fine,As they corrode you replace or as the engine mods change you then build new headers. :wiggle
Quote from: MikeLMRfatigue ? due to what loading ? Thermal fatigue maybe but not mechanical surely, otherwise all tubular manifolds would need to be this thick and i\'m sure most piston engine ones are not. Increasing the wall thickness could make thermal stresses worse
I was thinking about mechanical loading from the pressure pulses in the exhaust. Still, reading other posts it sounds like it\'s more about erosion / corrosion than anything else so I guess that\'s a red herring!
just found this link too ... looks spot on !
http://www.allstainlessltd.co.uk/products.asp
cool link Mike! I am gathering heaps of good info on this topic. Cheers everyone!