Exhaust header flange?

[tubov6cav]

Well I don't have the best welding skills or resources so I wanted to do this with virtually no cutting.

[3400-95-Modified]

Then your only choice is to buy the flanges as is; and the larger pipe and then butt weld the pipe to it... They will not go into the flange itself.

[Superdave]

Like I said in the PM, that's a terrible design. You might as well just use a pair of 3500 front manifolds and a few 2" U bends to feed the turbo. They'll way out-flow that setup and will last.

Welding stainless to mild steel flanges could also be a mistake without a good TIG. You might get lucky or you might get constant cracks.

[tubov6cav]

I didn't know I showed you that design, sorry Superdave. I'll probably just end up using 3500 manifolds then .

[Superdave]

I think it was one like that, it only showed up on tapatalk though. They save space for sure but man do they flow terrible. I'd hate to see you go through all that trouble and then be disappointed.



BCC should sell the flanges for them still, This is kind of how they would work in your application;



It doesn't get much easier than that, just a few 2" U bends to weld together and you're done. Remember to add a flex pipe between the banks though.

[3400-95-Modified]

I'm glad to see someone talking about flow when it comes to a turbo header... I feel that way to many people ignore that factor when designing turbo headers and think the log method is just fine... Flow on a turbo setup is just as important as on a N/A setup... It determines how log you'll be sitting there waiting for it to spool up

[tubov6cav]

Haha you are correct!

[tubov6cav]

What do you guys think of this design?

[caffeine]

Exhaust header flange?

I'm pretty sure those are 3900 manifolds

Do you even have room for a turbo behind the engine?

[tubov6cav]

I measured and I might. Would 3900 manifolds fit 3500 heads?

[caffeine]

Nope. But you can use stock 3400 or 3500 minivan manifolds for pretty much the same downpipe location

[tubov6cav]

Ok I'll check into that.

[geoffinbc]

You can weld mild steel to 304 by using 309 filler. The method of welding does not matter much. With a low restraint joint like a manifold you should not see any cracking. If you do you can butter the mild steel flange grind a flat spot for the pipe to sit on and then weld like normal. However remember that you will negate all the benefits of stainless steel in the area of the weld. All your corrosion resistance will be gone and it will rust.

[1988GTU]

Yes I am limiting myself I know. But I really want to make this work I know someone did it. Just not sure who this guy is.

Its not ideal, but it will work fine. Direction matters for anything for optimum performance with a log header, and it can be accomplished using butt-weld schd piping. It just raises the cost dramatically once you figure out what to use and start making cuts.

[ForcedFirebird]

Log manifolds work, and don't flow as bad as you would think in a turbo situation. You have to remember pressure is building in the manifold - usually 1.5-2x the pressure of the intake side of the system ie if you are running 10psi gauge pressure/boost, then your exhaust side is seeing 15-20psi.

Those weld elbows aren't the dimensions you are thinking, either. That is pipe and not tubing. The dimension is nominal inner dimensions. I have made turbo manifolds (log style) using it and the 1.25" listed is actually approx 1.4" ID and approx .120" wall thickness (again, nominal means at least x.xx" taking account for weld seems).

Yes, it can be a little expensive to use weld el's, but they are strong and will never corrode. Do a little more searching for better deals than Amazon, those prices in the pic are about double what you can find them for with specialty plumbing sites.

I build these for inline 6'ers...