Header/Manifold grade to use safely?
 

Hey guys. Anyone have any good info on which type of tubing should be used? EGT's will be about 1700 degrees max. for about 2-3 seconds max. I've heard of using .125" thick 304 SS w/ good results, but I've also found people saying it usually has about a 4 year life before they begin to crack. What seems to be popular is 321, but that ---- is expensive. Any good info on what should be used?

mild steel holds up to heat better than stainless. use mild steel and ceramic coat it. .125 wall is some thick steel and very hard to work with. ive used 1/16 wall forever with no problems. just add supports to the manifold to prevent heat sag.

Alright. Do you have anywhere in particular where you get your stuff ceramic coated? A few more q's you may be able to answer....

Do you heat the tubing if you need to work it into a shape, or does that harden it & make it harder to work?

I will be trying to make a merge collector, 3 into 1. Lets say I weld the 3 tubes together, overlapping the 3, making the center hollow, how hard is it to bend the 3 inward parts out to try and match up w/ the larger diameter throat? Should the throat and tubes be hammered to match, or try doing one or the other? I'm not quite sure of the easiest way to do that.

jet hot coating is the most popular but check your local area and see if there is a place close by that does ceramic coating. if your looking for a show quality finish then get it ceramic coated. if your not then dont worry about it.

1/16 wall can be shaped to a point. depends on what you plan to do with it. i buy all my tubing as a madrel bend kit with various bends so ive never had to heat anything to bend it.

if your making a collector your better off buying a weld on collector flange. making a collector requires a good amount of skill but you can always try. you want to cut all three tubing at a common angle taking out the same amount of material. its tough to explain by words.

Thanks, I will check out the local places. Last time I checked a few years ago, there wasn't really crap around here. Most places had never done headers, and the ones that did, wouldn't do the insides as well. WTF? I totally get what you mean by cutting off the tubes at an angle evenly. I'm not completely new to fabrication, I just don't have much experience. I've got a little engineering background and know AutoCAD, the only part I don't know how flexible the steel will be. Getting the "3-leafed clover" shape to merge into a circular throat is the thing I may have trouble with, but I'm sure I can bang something out. I've done a 2 into one a couple years ago and it turned out pretty good, but I didn't have to do a whole lot of forming with that.