I am in the planning on building some turbo exhaust manifolds and for primaries I have decided on Stainless seamless round tube, 1 3/4" OD .120" wall.

Question is will this stuff bend smoothly in a typical low buck tubing bender?

 

You buy mandrel bent pieces and cut and weld them to the desired pattern.

You can buy a mandrel bender but expect to use about 2-3 times more tubing than what's required. A bow and arrow type pipe bender pinches tubing. You'll need a proper mandrel bender.

Stainless or mild steel tubing isn't heavy enough to support a turbo. Pipe is more common.

 

.120" thick steel is heavy and i think its way to thick. stock headers are 16-18 gauge.... thats about 1/16" or .06" yours is .120 thick... i just welded my 6pt mild steel cage and it was .134" thick thats between like 1/8-3/16" thick. wayyyyy to heavy duty. those pipes are gona get hot and stay hot for a long time. too much heat soak. i would say also what u do is buy mandre bends or pieces and cut and weld them to what you want. not sure exactly about the diff of tubing vs pipe tho as he stated, by how he meant it....

 

But stock header material is too thin to support the weight and heat of a turbo.

 

Stanless steel has good heat properties, much better than mild steel, only downside is it has to be tig welded or welded with a special stainless steel mig wire, otherwise the header will fall apart after a while. .120 is SUPER thick, anyone who would buy these headers from you would be pissed because they would weigh a ton not to mention be more expensive. 16 gage is plenty. I agree with buying prebent mandrel tubing. I've built headers before and the piece together method is easier because you can make the bends go around each other instead of trying to guess what's needed bending it as one piece. Good luck!

 

Lots of online information on exhaust parts or building headers

http://www.magnumforceracing.com/sto...?CategoryID=31
http://www.popularhotrodding.com/tec...ech/index.html
http://www.carcraft.com/howto/ccrp_0...ers/index.html
http://www.carcraft.com/howto/0304_head/index.html
http://www.fastpts.com/cgi-bin/hazel...headerdiy.html
http://www.burnsstainless.com/TechAr...struction.html
http://forums.hybridz.org/showthread...=116979&page=3
http://www.chevyhiperformance.com/te...ems/index.html

 

My thinking about the "super-thick" wall tubing was that the headers would provide "some" support for the weight of the turbo. Also, another concern I had was the underhood temps. I had the idea of wrapping them in header wrap and was concerned about the header with thinner wall primaries burning up under the wrap.

 

that "super thick" tubing would also be "super restrictive". Tubing sizes are based on outside dimension, so the thicker the wall the smaller the inside dimension. so .120 wall 1 3/4" tubing would be more like 1 1/2" I.D. Not very big.

 

yea but .120 is almost an 1/8" thick. thats just too much. i would say stick with a 16-14 gauge, u could also employ a support of sum kind. like a trick peice of tubing that has sperical rod ends that bolts to something... just saying. i wouldnt buy header wrap ever! rusts out normal headers 3x as fast but if yours is stainless u wouldnt have to worry. i would def get them ceramic coated tho and im sure ppl would be willing to spend the extra $ for the ceramic coating... that will outlast header wrap, work alot better and look good at the same time.

i think the stock header material is 18gauge or thats what it is on my headmans... i would think that 16-14 gauge would be good enough, i would lean more towards 14gauge tho.

 

Do not use a cheap pipe bender. Pipe is measured ID, tubing is OD. Tubing Benders are expensive. I know, I have one. Your looking at $300 to $350 just for a die. Also, if this is going to be a Turbo setup, it needs to be tig welded. The little pieces of wire left inside the tube when you weld with a mig will tear up the blades of the turbine when they pass through.

 

I am sold on the thinner wall having re-read some of my turbocharging books and the links above. The exhaust ports on the heads I have are 1.55" sq. and hadn't taken into account the differences in cross-sectional areas.

I am not totally sold on ceramic coatings like jet hot having heard some bad experiences others have had with header coatings flaking off. Will search further in to it.

 

.120 wall tubing is just fine for building a TURBO exhaust header. has been done, is done, and will be done. no problem at all.

instead of trying to use a bender, use schedule 40 weld els to build a log. if not you cup of tea(a log header can support around 1000HP if sized correctly), use lighter guage stainless tubing, tig it if you can (mig will work almost as well) and build a long(er) tube header. with this you will need support for the turbo(s), and the additional issue of making sure as the header moves, nothing binds or contact, as the stainless tubing will move around quite a bit over temperature. check the forced induction forum here, or theturboforum.com for more info on building your own headers.