Cold pipe question

huntduck

huntduck

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Mar 19, 2012
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I'm needing some help. I'm wanting to put together a small set of compounds for my 06. Most of the cold pipes I see have been tig welded. I don't have a tig, but I do have a mig welder. I'm worried about having some debris left over after welding the pieces together. The pipe will be mild steel that I'll have coated afterwards.

Those that mig weld the pieces, do you just adjust your welder with some practice pieces and hope for the best? Or do you grind the inside smooth some how? I can't see how I'd do that with the bends and not seeing inside the pipe.

Thanks for the help!
 
I spot weld them or real short welds. Try to not weld uphill so you have more control over heat.Spend some time mating them with no gap.
 
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I messed around with some 5" exhaust pipe last night. I didn't get the cut perfect, so it had some gaps and I blew thru the pipe there. But, where it was fitted tight, welded nicely with no left over boogers inside. Short spurts worked the best.
 
I welded mine with a mig and it ended up pretty good in my opinion. Just take the time to ensure a tight fit. I would say overall beveling makes the most difference in not blowing through. Generally you can get away with a lower power setting with a nice 45 degree edge that goes halfway through on the pipes, while still getting full penetration of the weld. :Cheer:
 
I learned a tight fit is necessary last night. I didn't think about beveling the pipe.
 
Take a section of the size of the pipe your working with and cut it in a 1" long piece. Then cut the 1" piece in half so you have too cresent moon shapes. Trim each end of one moon shape a 1/8" or so. Then slide the cresent moons half way into on of the pipes you welding. Slide the other pipe over the other half of the cresent moon pieces. Now leave 3/32" gap and you can weld it up this way. You will have a solid back that you won't burn through and a good solid weld.
 
A tight joint is a must and don't bevel as then you're making thin tubing thinner thus harder to control blowing through.

Run a ball style hone through the piping afterwards to get any slag out of the inside of the tubing.
 
Woo hoo!! Great ideas! Whitneyj, a ball hone isn't that flexible? My thought is, that would work for the straight piece to 180* that'll go to the secondary turbo. What about the 90ish* from the straight piece to the primary outlet?
 
It should flex with the bend as long as it's not a solid shaft mounted hone.
 
I have only used 0.035" wire.
-Found out long ago that any gap results in a big hole while welds.
-Too slow of wire feed results in poor penetration, and the weld just piles up on top of the pipe, not in the pipe.
-magnets help to hold the pipe pieces together.
I also use 3" angle iron to hold pieces lined up together. (The "L" or "V" channel)
-take your time...stop and let the pipe cool off every now and then, as I have found that welding too long of a pass will pre heat the pipe too much, and help blow a hole through it.
 
Thanks for the tips. I've ran smaller wire before, just messing around in the garage, didn't like how it behaved. I usually run .030 wire.
 
Ghostman said:
Take a section of the size of the pipe your working with and cut it in a 1" long piece. Then cut the 1" piece in half so you have too cresent moon shapes. Trim each end of one moon shape a 1/8" or so. Then slide the cresent moons half way into on of the pipes you welding. Slide the other pipe over the other half of the cresent moon pieces. Now leave 3/32" gap and you can weld it up this way. You will have a solid back that you won't burn through and a good solid weld.
Click to expand...

This is probably the most sound advice. I'd probably just take a section of maybe 1/2 to 3/4" wide tubing, slit it and trim it down so it will just barley fit to the ID. That will be the backing. If trimmed correctly the spring tension should keep it in place until it is welded in solid.
 
I must of missed that one? Once welded, those backers will come out correct?
 
Nope, the backers are permanent and fused to the outer finished pipe. Small minor bump in the airflow, but not enough to affect flow in a boosted environment. If this was a non forced induction intake pipe, you wouldn't want to add any sort of internal obstruction.
 
Thanks for clarification. I didn't think they would......wanted to make sure!
 
Any progress? Oh yeah on the beveling suggestion I was assuming the use of heavy gauge pipe. Not the thin cheap stuff.
 
Big Blue24 said:
Nope, the backers are permanent and fused to the outer finished pipe. Small minor bump in the airflow, but not enough to affect flow in a boosted environment. If this was a non forced induction intake pipe, you wouldn't want to add any sort of internal obstruction.
Click to expand...

Boosted or not, obstruction has same effect.
 
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