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I want to build my own manifold. Thoughts/ideas?

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Gamble97

15+ Year Contributor
2,642
63
Jan 3, 2006
small town, Illinois
I want to try building my own dsm turbo manifold. Not really good at stainless so I am thinking of trying some mild steel. A friend of mine is going to give me his junk 1g head. However I don't have a dsm anymore and just going to do it off my head for room and such.
Anyone have any good ideas/designs for a simple/basic build. This is more or less a way for me to test out my skills. When it's done I'm going to try and sell it to a local for whatever I have into it, just so I can do another and another and work my way on up with doing these.
Any tips/tricks/advice/thoughts etc would be helpful.

And when welding on the head flange, should it be bolted down to the table so it doesn't warp? OR should it be snug with a spacer inbetween so it leaves a place for the heat to escape? Or do you do very small sections at a time and let it cool completely before restarting?
Also part of the reason for starting with mild steel is because it's less expensive and more forgiving than stainless when it comes to warping.
 
When I built mine I ran into the same problems you mention. I built mine out of mild steel first as a test of what I wanted. It was before manifolds were available for the Holsets. I didn't bolt it down and it warped bad. I had to get it milled flat and welded another flange on. Bad aspect of MS is that it rusts from the inside out unless you get it coated inside and out.

I just bought a set of tack weld clamps from icengineworks to help with my next build.

My biggest PITA was getting the tubing lined up and meeting when doing the 1-4 2-3 setup for twin scroll setup. I'm thinking of making mockup foam tubing to mock up first.
 
When I built mine I ran into the same problems you mention. I built mine out of mild steel first as a test of what I wanted. It was before manifolds were available for the Holsets. I didn't bolt it down and it warped bad. I had to get it milled flat and welded another flange on. Bad aspect of MS is that it rusts from the inside out unless you get it coated inside and out.

I just bought a set of tack weld clamps from icengineworks to help with my next build.

My biggest PITA was getting the tubing lined up and meeting when doing the 1-4 2-3 setup for twin scroll setup. I'm thinking of making mockup foam tubing to mock up first.

How thick of a plate do you think it should be bolted down to? Would LOVE to find a copper plate at least 1/4" thick for this. That would be awesome.

I think the biggest challenge is welding to the collector. Or if I should just weld all the runners to the flange. That part I haven't though about yet.
 
A couple tips.

Make everything go north and south as much as you can. Fitment is HUGE!. Ill fitment causes stuff to warp. You are filling gaps and that causes the metal to pull all over the place. Merge collector is also huge. It will take you more time to design a jig for a merge collector than actually making the manifold. Try to keep weld els complete. This keeps the amount of welds down.
 
I would suggest doing a Fabrication thread on this. I'd be interested as i'm sure so would others, on obstacles you ran into, as well as ideas you found that worked.
 
I would suggest doing a Fabrication thread on this. I'd be interested as i'm sure so would others, on obstacles you ran into, as well as ideas you found that worked.

I will when I order stuff, but the main issue is that I don't have a dsm anymore. So a friend is going to let me borrow his head.
 
Almost forgot I used a 3/8" header flange. And on that note I suggest you get the CNC flange that goes from the rectangular outlet to the round outlet. Cuts down on the headaches.

Also it should be brought up proper header length. It does matter, and if someone could bring up a valid answer to this it would be greatly appreciated. I made my first one to just fit. I used a header calculator that gave me 37.75" tube length but thinking that's not right.
 
When I built mine I used 1/2" flanges bolted down to another thick piece of steel when welding them. I didnt have any issues with them warping. I used sch 40 pipe and mig welded it together. After I was done I cleaned it up and painted it. It turned out great and is still holding up after over a year of abuse holding a Holset.

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Looks great, but how did you weld around the collector with a mig gun?
 
If it were me, I'd use a stick welder in those tight spots that a mig won't reach. For you Gamble, make a box with a glass top, then fill with argon and you can use a little cup and long tungsten. Also keep in minf there are different torches you can buy.
 
If it were me, I'd use a stick welder in those tight spots that a mig won't reach. For you Gamble, make a box with a glass top, then fill with argon and you can use a little cup and long tungsten. Also keep in minf there are different torches you can buy.

I'm no good with stick welding. I was wondering about different torches, wondering if people really take the time to swap them out for each manifold they build or not. Mig would be great, but I'd have to find tune my mig skills. Maybe I'll do 2. One mig and 1 tig :)
 
Looks great, but how did you weld around the collector with a mig gun?

It was very difficult. I made one of the tubes shorter so I could weld the center of the joint with the mig gun and then added a 1" tube to that tube and welded as much of the outside as possible and did a pass on the inside as well.
 
A couple tips.

Make everything go north and south as much as you can. Fitment is HUGE!. Ill fitment causes stuff to warp. You are filling gaps and that causes the metal to pull all over the place. Merge collector is also huge. It will take you more time to design a jig for a merge collector than actually making the manifold. Try to keep weld els complete. This keeps the amount of welds down.

I agree

here's an informative site

Merge Collector Fabrication 101 - Honda-Tech
 
You'll be fine with mild steel. I would use 1 1/4" sch 40 elbows and pipe. 1 1/2" is unnecessarily big. A belt sander can help a lot getting those flanges to fit perfectly.
 
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