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