Ok so I'm using some schedule 10 stainless pipe and some 3/8" thick header flanges.
The inside diameter of the pipe is actually 1.625" and outside diameter is 1.90"

So..... The pipe is round and the ports on the head are retangular (I think)..

I'm wondering if I should try to shape the stainless pipe to the port design or just get a round header flange to weld to? Will it affect flow that much??

Probably going to get a 1 3/4 port flange so I can weld from the inside then port match a little

 

Shaping might be hard to do with sch 10. Try if you can but it wont hurt flow much if you made round to square. Exhaust is high pressure fast flow and will expel regardless of shape. Most of the flow comes out the center of the port anyway so minor mismatch doesnt hurt. In fact a small step at the flange to head makes for a nice anti reversion step

 

I'm thinkin' that a wall that thick is gonna' make them heavier than they need to be and a 1.90" OD is gonna' make life miserable when choosing/installing bolts.

 

you better off getting a header kit from speedway it comes with all the bends and flanges

that pipe is way to thick and not much better than stock and the heat soak will be rediculous makeing your whole engine bay hotter

 

Well... The manifold needs to support the weight of a turbo and be able to handle the heat without cracking like egg. I agree the bolts are gonna be a bitch.

 

I didnt even consider bolts. I have 1.75" primaries 16ga and its close to the bolts. Probably need to shape the tubes and grind for clearance at 1.9"

 

regular header kits can support a turbo weight unless you are using S480s and get better flow

 

From what I hear regular header kids will sag and crack eventually from the heat and stress of the weight of the turbo. I do not want to have to make these three times.
I think what I will do is shape a piece of inch and a half pipe to the rectangular port before I make the turn with the 90° elbows

I forgot to mention that I making a long style manifold. An idea I got from an article about eight second Turbo LS1 Camaro. That team used stainless sch10 log manifolds.

 

Yeah, I had to contact Don for a specific ARP PN for his headers and it was still challenging.

 

The ARP 5/16 heads are probably your best option for bolts. Good luck still... Sounds like its gonna be a PITA

 

best solution is to get some stahl pattern adapters, bolt them on and build your headers with the stahl patterned flanges. No more bolt issues

 

That's the ones!