Inconel Exhaust Manifold

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Dropd94Ranger

Forum Member
We're research the idea of fabbing an Inconel exhaust manifold for our Formula SAE car at school. I was wondering if anyone has every done this. It's super light weight and retains heat very well also (perfect for a turbo'd race car). They actually use them in F1 and Indy Cup series cars....
 
Pffttt have you ever tried to machine Inconel????????? Good luck with that. Its used in a ton of stuff on Air planes and Jets. But man its a bitch to work with. We have made a bunch of stuff for the air industry before. But most of it was wire edm or carbon edm. The stuff that I had to nmachine was a bitch. No really goood way to fixture it. I would look in to SS. just my .02
 
Dropd94Ranger said:
We're research the idea of fabbing an Inconel exhaust manifold for our Formula SAE car at school. I was wondering if anyone has every done this. It's super light weight and retains heat very well also (perfect for a turbo'd race car). They actually use them in F1 and Indy Cup series cars....
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They use them in $$ is no object racecars. I might be dating myself, but when I ran FSAE, you were limited to $8500 piece cost for the whole veeeee-hicle. Might be a bit more now (it's been 11 years) but inconel is big $$ compared to other components. Stainless is a better option, but I would only go to stainless if you can't get thin wall tube steel to live. With the tiny restrictor on the engines, it's hard to accidentally run the A/F ratio lean, and unless you are doing some pretty major spark retard, you are not going to cook the headers too bad.

Here's my soapbox.
I know a several FSAE judges. They are not impressed with swoopy parts. They will want to know if a cheaper simpler part was tried.

My recommendation that will impress the judges:
Come up with a design that has the best cost vs. mass. vs. performance tradeoff (hopefully 0 performance tradeoff). If you didn't do your homework, they will know. Unless you are doing turbo, a thin wall header is your best bet.
 
I think you're over thinking this. Make a good flowing mild steel header and call it
a day. You aren't going to save much weight anyway and you WILL struggle with fab and welding.
Put your energy into lightening larger components if that's the goal.
 
This is going to be on a turbo'd Honda F4i (600cc) engine. The reason we are looking at this has a lot to deal with thermal retention. The way the engine is configured in the car leaves the header a couple of inches from the drivers seat (the driver actually got 2nd degree burns from it, despite the $1000 carbon fiber aircraft matrix firewall). The competition frowns upon using things like header wrap (the cheapest way to go).

This was one of our "way out there ideas" and I was just wondering if you guys have worked with this material before. Reid-Washbon Racing quoted around $3000 to get the manifold made, but if we could get the tubing bent (1.5" primary with probably 0.020" wall thickness) we could weld it up in-house. I've heard the technique for welding is the same as stainless just a little "different."

We're still research other ideas, so I think we may just go with a ceramic and thermal barrier coated stainless steel header. Like beertestr said, this whole competition is about keeping the cost of the car down (under $25,000 after completion) while keeping reliability and manufacturability up. Even though last years was around $70K to make, it was costed out at $15,700.
 
Use air gap style tubbing arangement. It will hit both of your targets easily and be the easiet least exspensive thing to build.
 
Dropd94Ranger said:
This is going to be on a turbo'd Honda F4i (600cc) engine. The reason we are looking at this has a lot to deal with thermal retention. The way the engine is configured in the car leaves the header a couple of inches from the drivers seat (the driver actually got 2nd degree burns from it, despite the $1000 carbon fiber aircraft matrix firewall). The competition frowns upon using things like header wrap (the cheapest way to go).
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Put in a double firewall. Put one layer 15-25mm from the next. Extend the rear one down a bit more than the front one so that I catches air, and leave to top of the gap open too. OR put a heatshield ~15mm off the thurbo and manifold.

You'd be amazed at what a little clever design will do for $5 worth of sheet aluminum.

College guys :rolleyes:
 
beertestr said:
Put in a double firewall. Put one layer 15-25mm from the next. Extend the rear one down a bit more than the front one so that I catches air, and leave to top of the gap open too. OR put a heatshield ~15mm off the thurbo and manifold.

You'd be amazed at what a little clever design will do for $5 worth of sheet aluminum.

College guys :rolleyes:
Click to expand...

It's all been done including the addition of an aerospace spec. carbon matrix firewall...The most difficult thing is packaging everything in the tight area. I wish I had a picture of it, that would let you guys know what we're dealing with...I've contacted a company (Reid-Washbon Racing) about sending us some scrap Inconel 625 to see if we'll be able to weld it.
 
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