Twin Piping

1

1939dodge

Still Learning
I am going to start fabbing up my twins in the coming weeks. As for the tubing / Pipe I can get sch 40 weld pipe which will be more structural or I can go to the semi truck parts yard and pick up some old exhaust or turbo parts, cut them and weld them together... Which direction would you suggest? I am leaning to steel based material for ease of welding I do not want to deal with aluminum.

The Sch 40 will be heavy but stout, not cheap but not that bad. The place I am looking at does not have SCH 10.

Is there a better cheaper way to get the fittings I need??
 
The set I'm putting together now has a schedule 10 stainless hotpipe, most of them I've built I used schedule 40 three inch for the hot pipe. I've had a 3b hanging off of my 341 for two years now without a brace. Like Ron said mandrel bend exhaust tubing for coldpipe.
 
I used exhaust tubing for everything. I have a support for my bottom turbo, hot pipe takes little to no weight.
 
Thanks for all of the ideas and the link, they do seem to offer a good selection and fair pricing.

I am not really set up for stanless welding (I do not have the tri-gas mix or the wire) so I am leaning to steel and painting or something. Thoughts on that, should I just go for it with the wire and normal gas I have for MIG welding steel? I do not have a tig, I would love for it to all look smooth and clean I guess that is one of the reasons I like SCH40 it gives me more material to sand and make perfect.
 
The inside of the pipe will matter more than the outside appearance. If you MIG it, please make sure you clean out all the weld BB's and slag. I've seen too many turbos come to the shop chewed up wheels from FOD.
 
joefarmer said:
The inside of the pipe will matter more than the outside appearance. If you MIG it, please make sure you clean out all the weld BB's and slag. I've seen too many turbos come to the shop chewed up wheels from FOD.
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Yes, that is one of the reasons I like the thicker material, less potential for burn through and it allows me to go back and really sand the inside smooth and not worry anout thining out the pipes too much.
 
Schedule 40 3" is the ID which works out to 3.5" OD to match your other piping and works out much better for good weld penetration on a thick weld flange. 3" ID is perfect to keep velocity in twins and if you use thin 3" exhaust tubing I think it looks a little strange. Primary turbo bracing is a must if you like your manifold, but there are some running without them.
 
I think I will definately use SCH40 for the exhaust side, but I can get the semi truck exhaust elbows for around $5 each! That is going to save me some serious coin. I am also going to look to see if I can find some tube with the flanges already attached that I can use.
 
I usually build everything but I bought a flange somewhere that had the round on top for the three inch and transitioned to the rectangle on the bottom. Really nice piece. One I built I cut the hole round and cut some angle slut out of the slut to make the transition to the narrower rectangle.
I never seem to build two alike, the one right now out of stainless I've got a jig built to press the end of the tube out to the rectangle.

As to the stainless hot pipe, I just used regular mig wire welding it to the steel flanges, penetration seemed really good and welded fine. The stainless is a little harder to work with but cuts fine with a standard portaband.

It's a lot of fun building something from scratch and trying to save as much money as you can. Amazing what you can do with a little scrap iron and time.

Flanges aren't hard to make if you have a buddy with a lathe. Hole saw the rough circle out and lathe the piece to a flange.
 
"Hole saw the rough circle out and lathe the piece to a flange."

1/2" wall 4" DOM works well to make hx40 flanges on the lathe. No hole saw required.
 
Yeah I wish I had a lathe and wish my bandsaw did not just catch fire. I know flanges are not hard to make they have 5 holes in them, fairly basic. I am thinking it would be easier if I had one with a bit of tube and flange. Also I have been thinking of pressing the rectangle onto the round pipe to make it easier... We will see how it comes out. First I have to figure out where I am going to set the turbos.

Here are some photos of what I have been trying to figure out. I am trying to finalize the location of the turbo, compressor and where to put the compound turbo. I had to take the waste gate off to get the turbo to fit in a few places, if I put the turbo down it is so far back the exhaust is going to be difficult. Forward and up and there is little room for the alternator.


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phoca_thumb_l_Turbo%20Close%20To%20Valve.jpg


phoca_thumb_l_Turbo%20Down%20Close.jpg


phoca_thumb_l_Turbo%20Down%20Front.jpg


phoca_thumb_l_Turbo%20Valve.jpg


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I built mine with a 3" schedule 40 hotpipe and shaped one end into a rectangle by heating it up with a torch. Also I mare my own divided T6 flange out of 1" plate, just torched it out and filed it flat after it was welded up. When you use exhaust pipe on the cold pipes if your worried about slag cut a 1" long piece of exhaust pipe and put a slot in it so it will just barely fit inside of the two ends you want to weld together, it will keep the slag out and help from burning through. If your using a MIG it shouldn't be too bad, I used a stick welder on mine, I had to be very careful.
 
I see many people mentioning 3" I thought I calculated that 3.5" ID was ideal meaning like a 4" SCH40 would be as close as I could get unless I go smaller to 3".

My concerns on thinner wall are two fold, I do not want to burn through and throw slag, but I also do not want to be too careful and miss spots or cold weld losing boost pressure. But as I mentioned I can get 7 used pipe elbows for the price of one SCH40 elbow.

I can not wait to get some tube and get the saw working again so I can have some fun.
 
Schedule 40 elbows should only be $15 or so, that's all I've ever paid. On the exhaust pipe I do one pass just dabbing the rod to the pipe making just very small welds on the first pass, then come back over it with a cap weld.
 
$15 would be better, what size are you talking about? Also the tight radius 90* is more here. At your pricing it may almost make sense for me to have you buy them and ship them to me... there must be a better place to buy them here. Where are you getting yours?

Yeah I planned to tack everything make sure it works then do the full welds.
 
Muddin_dude06 said:
Schedule 40 elbows should only be $15 or so, that's all I've ever paid. On the exhaust pipe I do one pass just dabbing the rod to the pipe making just very small welds on the first pass, then come back over it with a cap weld.
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WHERE? :eek: All the ones Roachie has posted from McMaster Carr are like $30-40
 
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