Turbo Header Questions

[engnerdan]

I have 2 friends both looking to construct some turbo headers/manifolds (which ere you want to call them). I would like to know which is better to fab the headers from, sch 10 304 weld elbows and pipe or a DOM tube like 347 stainless. I know the 347 is better with the heat but does the thinner wall handle it adequately for a turbo application.

[4sfed]

I have 2 friends both looking to construct some turbo headers/manifolds (which ere you want to call them). I would like to know which is better to fab the headers from, sch 10 304 weld elbows and pipe or a DOM tube like 347 stainless. I know the 347 is better with the heat but does the thinner wall handle it adequately for a turbo application.

The design will make more difference than choice of material. The expansion coefficient of stainless is higher than carbon steel, so you need to build in some flexibility with a slip joint or bellows. And don't expect the header to support the full weight of the turbo. Even stainless steel loses a lot of strength at operating temperature . . . but keep in mind the expansion of the pipes.

Unless you can bend your own tubes, you're choice of material is 304 or 321, which contains titanium instead of columbium . . . and works just as well in preventing carbide precipitation. I haven't found anyone selling pre-bent 347.

304 works fine for the street where your operating temperatures are relatively low most of the time. It's less expensive and you have the choice of thinwall tubing or schedule 10 weld fittings. The weld fittings are (relatively) inexpensive and tighter radius than the bent tubing, so it's easy to make a compact manifold. On the other hand, the larger radii are better for horsepower.

I've only found 321 available in thinwall tubing but it's the best choice for racing where you'll run "on boost" (high temperature) a high percentage of the time.

Jim

[Q@EPM]

This is what I do for a living. If you need help juss shoot me a PM I can guide you in the right direction.

[4sfed]

This is what I do for a living. If you need help juss shoot me a PM I can guide you in the right direction.

How about posting some photos of the manifolds you make?

Jim

[PatrickW]

I also have some questions about constructing exhaust manifolds.. heres one I got from a friend to refinish but I need to figure out how they make these, I'm sure they're robotic welds but there's got to be a way to get close manually tig welding them.





My main reason for asking about this is I'm constructing some stainless exhausts using 304 material and the welds just aren't up to par with the kind of work I like to put out.

The welds I'm getting now are just discolored and look like ****, they don't have any luster to them, just gray and rough which i know is from too much heat but i like to take my time when I'm welding so there has to be some trick that I'm missing out on.

Thanks guys!

[mtlmster]

The headers in the pics are nice!

The reason I'm piping in here NPI I'm a welder, and I learned 20 years ago when welding SS I use Solar Flux to back my welds. Makes a big difference.

You can find it in Ebay.

Steve

[Showdog75]

The headers in the pics are nice!

The reason I'm piping in here NPI I'm a welder, and I learned 20 years ago when welding SS I use Solar Flux to back my welds. Makes a big difference.

You can find it in Ebay.

Steve

It's not as good as argon. No clean-up with a argon purge.

[Showdog75]

Patrick those are not robotic welds. I do robotic welding and alot of hand tig welding and can tell from the photo they are nice welds but not robotic. You can get nice clean welds like those if you'll be a stickler for the little details. For one always clip the ends of your wire after each bead.Also always keep the end of the filler under argon coverage at all times while the tip is molten.I think stainless is the easiest of all materials to keep looking pretty but you can't get it to hot. One way to get it to hot is welding it to cold , yes thats right to cold as it put more heat into the piece the longer you hang around in one spot.

[PatrickW]

so i should give it as much power as i feel I can without it dropping out or blowing through.. i havent tried back purging yet and i usually clean everything well but what do you use to prep it to weld area? Im using shop towels with naptha, after going over it with a green scotch-brite pad on a die grinder.

Im aware that I should use a fresh pad for stainless so it doesnt get contaminated with any other metal so i usually get a new pad and new towels when im prepping something like this.

Also I usually keep the tungsten very close to the puddle so im sure that its not outside the gas flow and i have post-flow set to about 8 seconds and always let it there for that amount of time.

Il post some pics up tomorrow of stuff that I have done

[Q@EPM]

First off get you a gas lense for your torch. it will make all the difference in the world as far as looks goes. It will even help on the back side, back purging is the best option, solar flux works but is messy and sometimes hard to get to the spot you are welding. Try the Gas lense, they are very cheap and you will notice a substantial improvement in your coloration and consistency. IDK if your machine has a pulse feature but if it does this too will help but is not neccesary for pretty welds.....As for the picture you posted, that header looks like it came from China. I see it all the time, some poor guy sits all day Tig-ing the same part over and over again. He will get proficient for sure. As I mentioned if you want some info just PM me about sourcing tube/etc...keep at it you will get to where you want to be.