Tubular Header for Cummins?
 

We're thinking of starting work on a tubular header for my 12V. Planning tentatively on 1.75od/.120 wall stainless. Anybody have any comments on this material choice? Too big/small? Just want to make sure we do this thing right the first time. Thanks.
Chris

I think that as long as the ID is the same size or slightly larger than the ports in the head that should be big enough. You probably wouldn't want them too much larger than the exhaust ports, you probably want them as small as possible without restricting flow coming out of the head. The larger the volume is the longer your turbo lag would be.

As far as material that shouldn't matter too much just depends on what kind of look you want I guess. That would be pretty cool though. I wonder if you would loose a lot of energy through the header tubes though and loose efficiency though. Would you get them ceramic coated? Also how much do you think they would want to expand when they got hot, making it hard to keep a seal?

Just some of my thoughts, Aaron

Well, I'm hoping that by going with stainless, we'll minimize our expansion/contraction due to heat. I too am concerned with losing velocity and heat, so I figure we'll keep the runners as short as possible. Anybody know the CSA of the exhaust ports?
Haven't looked into any of the ceramic coatings yet, but as long as there is no problem coating stainless, then yes, we will be coating it, as well. Thanks.
Chris

The ultimate header/manifold coating is Swain's WhiteLightning or whatever they call it.

http://www.swaintech.com/header.html

Stainless should work, but may not be best? .120 is a good choice, imo.

YOu can go with bigger diameter tube if you want with little to no ill effect, unlike a gasser. Your manifold basically serves as a reservoir of hot pressurized gas waiting to go through the turbine. Compared to the T-housing, the manifold's restriction is nil. I'd go large enough to ensure that the tubing was about 1/8" larger than the port opening. This will give you a measure of anti-reversion in the exhaust manifold, with no ill consequences. This is important as drive pressures come up and the engine has to fight harder to breathe.

jmo

FWIW....Be careful with stainless. I've seen stainless exhaust systems grow up to 1 1/2" in length after heating up.

Someone posted some homebuilt header pics a few months ago. Theyre here somewheres.

If you're going to coat it, why bother with stainless? Maybe regular Mild steel would be a better choice, especially after coating it?

I'd have to think it may be cheaper.

If you are looking for materials, check these guys out. Plus, they can probably give a great recomendation on materials. They can tell you what you need 304, 321, or Inconel.

http://www.burnsstainless.com/

I don't think you would want to use stainless unless you wanted something shiny under there and for it to stay shiny. It will still probably start turning blue after awhile.

would it be an advantage to make the tubes equal length or does it matter since there is a turbo there?

It doesn't matter because of the turbo. Shorter is best, you want to minimize heat loss.

What about wrapping it it with some of that insulation like what is used on gasser headers? Would that help keep heat in?

I think twins would be easier, then you could clock the turbos for more room/clearance. I saw a pic of one around here somewhere

Clock the turbos ? :confused: What is that?

[duhhh] I mean more like turn them or even have one 90^ to the other. Clocking would be what I desrcibe as changing the position of the exhaust housing to the compressor housing. How ever, that might be needed if one turbo is mounted 90^ compared to the other for more room else where, like trying to keep the tranny cooler on a 2nd gen auto truck. Understand?? I hope.[laugh] Got my terms mixed up.