GI: Replacement exhaust manifold

T

thepope540

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2003.5 Yellow Speed - Sold, Spicy - Sold, #639 Black Mica
The manifold will be $475 shipped for a base manifold. O2 is a $25 option. EGR will be a $25 option, and EWG will be a $50 option. For those interested in EWG, I'll also be offering a simple dump tube but I haven't even started looking at that yet.

The manifold is all 304SS, 1/2" flanges, and schedule 10 pipe for a good solid construction. I'll have more pics as the prototype is refined and gets final assembly.

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Good to hear that you are thinking about doing this. I want a cast iron manifold replacement. Mazda should have made ours to last like they did with the old F2T engines. When I sold mine after 16 years, it still was intact and had no cracks or hairline fractures. The Calloway material leaves a lot to be desired.

I want it to fit underneath my polished heat shield.
 
Tubular would certainly be easier to produce - it would just be so much more work to build and I wouldn't be able to guarantee the same level longevity. I feel that my downpipes are lifetime parts. It would be tough to offer that in a tubular manifold - not impossible, just tough. The exhaust mani is second or third on the list. First is getting the downpipes reworked on the site and getting the water neck spacers ready. Second is the intake manifold and then finally the exhaust. Lets keep this thread going with ideas so when the time comes I can get the part going quickly. Thanks Guys!
 
I wouldn't be against a steedspeed type. With just machining one out. It would cut down on the cost of having a casting built. I bet since Steedspeed is no longer offering the manifolds he would prolly sell you the CNC program.
 
The longer the runners the more room the exhaust pulses have to expand before being crammed into the turbine. It allows the engine to spin more freely and adds torque everywhere on the curve. I would vote for tubular for performance, but the fact is, the entire weight of the turbo and exhaust is on the manifold. That little support bracket on the stock S pipe isn't doing much.

It believe it is this weight more than the heat that causes the manifolds to crack. People that put on aftermarket downpipes without it and remove that bracket even more so.

Maybe there is a way to CNC a solid piece between the engine block manifold and the T25 flange, and then run tubular pipes from each port up and out a bit before curving down into the collector. That way you would have long runners but they wouldn't be supporting the weight of the turbo and exhaust.
 
Not that it matters to me( I already have my set up), but it would be wise to see if the manifold can be moved slightly over to help in the placement of a larger downpipe in relation to the waterneck.
 
TURBOJ1 said:
Not that it matters to me( I already have my set up), but it would be wise to see if the manifold can be moved slightly over to help in the placement of a larger downpipe in relation to the waterneck.
Click to expand...

No because you are taking a small market (people who want a aftermarket manifold) and making it smaller (people who want/have both a aftermarket manifold and downpipe.) It would be better to just make a stock replacement.
 
what sort of material are you thinking? If you do tubular I have DXF files that have the t25 layout and the exhaust manifold hole pattern. PM me if you want these. No cost to you. I just want to see these happen. I actually have 1 or each piece cut out if you want those too. 1/2" thick 316 stainless. LMK
 
I would like too see a tubular mani with an external wastegate. Too bad steedspeed went out I just got my tax return now who do I go with??
 
Sounds like its going to be tubular. I'll just have to work on finding ways to make the manifold flow well and still be robust. Some sort of support structure will be part of the package.
 
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