So I'm pretty discouraged right now...I consider myself a good welder, and I have made cages, intake/exhaust mani's, IC end tanks, boost pipes, etc. etc.

At any rate, I can't seem to find a single effective way to making a tubular/equal length mani in a REASONABLE time frame. I learned my lesson that once welding out the runners separately will cause them to basically not fit. So, the next time, I welded as much of the runners as I could before breaking the tacks off to fight the warpage. This doesn't even seem to work either.

I built this manifold last night, welded about 60-70% of the runners with the whole thing tacked together, then broke the runners off to weld the rest. I *literally* spent over 4-5 hours welding these out to fight warpage. I'd weld 1/4 a section, move to the next runner, 1/4 the next, etc etc to stagger heat as much as possible. Not fighting gaps either...Here are the pics of how those runners fit now... If I spend 8 hours to completely fight warpage, then whats the point of even making one to sell? Any advice would be great.
Weld pic to reference decent welding:


mani to be welded:

And results after trying to put it back together in the jig:

 

I usually have a game plan of how im gonna do my whole manifold then do one runner at a time and weld each runner 100% as i go along... i can sometimes knock out a totally custom manifold in 3-5 hours!

 

I'm no expert; hell I don't even weld.. buttttttt.... it looks like you could start and both ends.. tack runner to flange & collector and work your way inward.. that way if there is a little warpage, you can compensate with your positioning of the next runner. badass welds though

 

this may be something simple. are you keeping the tubing at the same spacing and position after you break the tack welds off? this might be your issue.

and no, i'm not a welder, either, but this could easily cause your problem. it's like you're not welding everthing together in the same position it was tack welded in.

 

Are you tacking all the tubes in at least a few different places before you weld them?

On a side note, i've noticed alot of people cutting a straight tube at an angle like you did for #3 on that manifold at the head flange. You realize how bad that is for flow? That's no different than taking a straight tube and cutting a 45deg. angle on it for a downpipe. You'd never do that, would you?

 

You have to have them bolted or tacked to something when you make a full pass. Also to prevent warpage, try searching for a product called cold heat. I posted it not to long ago, works pretty good.

 

Thanx for the replies... Vanillasky, i dont really see what you're saying.

Tony1-thanx for the heads up. I am running at least 4 tacks on the pipe before making a pass.

90blackcrx-do you just smear that stuff everywhere but where youre welding or what?

 

Yep

 

Heat Fence is probably the same thing.

Consider: If you want something to warp, you heat it and cool it and repeat... so by welding a little and then jumping to another runner, you're only making matters worse.

When welding, weld from 12 oclock to 3, then opposite quarter of 6 to 9...then do the remaining quarters. Pay close attention to where the parts will warp when welding, and with practice you can control which direction it will warp and how much....based on where you start and stop the welding.

Also, while it's still hot, you can use compressed air to cool the side of the weld that you want to shrink up (draw). This works better than water and is a lot neater.

 

Great info Engloid! . Question though, why would you want to draw a weld in a certain direction? How would that apply to a runner where you want it to fit just like how you had it tacked up?

Also, I am not really getting "warpage"...more shrinkage than anything. Everything still "lines up", the runner just sits with a 1/2" gap back from the head flange...like the pipe to the head flange literally got shorter. Improperly placing the collector is out of the picture also due to the jig...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ChainbreakR &raquo;</TD></TR><TR><TD CLASS="quote">Great info Engloid! . Question though, why would you want to draw a weld in a certain direction? How would that apply to a runner where you want it to fit just like how you had it tacked up?
</TD></TR></TABLE>

Now that it's drawn up where it doesn't fit, wouldn't it be nice to warp it certain directions to make it fit again?

Wouldn't it have been nice if you had known so well which directions it would warp, based on where you stopped and started, that you could have kept it straight to begin with....by a careful process of pulling on way, then the other?

 

interesting...that sure would be nice! I wish I had time to practice these kinds of things. How do you explain/combat the "shrinkage" though? notice the last pic posted...it didnt warp in any direction...just sucked back. In fact, the 4th pic is the only runner that actually warped.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Engloid &raquo;</TD></TR><TR><TD CLASS="quote">
....by a careful process of pulling on way, then the other?

</TD></TR></TABLE>

Just to clarify, what you're saying is: if you weld the tube in 4 equal quarters, it won't warp at all, or as much?

Assuming you're welding all in the same direction around the tube (clockwise or ccw) do you split it up like 1,3,2,4 ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ChainbreakR &raquo;</TD></TR><TR><TD CLASS="quote">interesting...that sure would be nice! I wish I had time to practice these kinds of things. How do you explain/combat the "shrinkage" though? notice the last pic posted...it didnt warp in any direction...just sucked back. In fact, the 4th pic is the only runner that actually warped.</TD></TR></TABLE>

Some amount of shrinkage is unavoidable. You may find that you have to make the fixture for your runners a bit larger to compensate for the shrinkage. The amount of shrinkage will depend on your welding habits, whether you let it cool between passes, and for how long, amperage, travel speed, etc.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Paul_VR6 &raquo;</TD></TR><TR><TD CLASS="quote">
Just to clarify, what you're saying is: if you weld the tube in 4 equal quarters, it won't warp at all, or as much?</TD></TR></TABLE>
It depends, as written above. With practice, you can learn to warp things back where you want them if they do go the wrong way the first time.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Paul_VR6 &raquo;</TD></TR><TR><TD CLASS="quote">Assuming you're welding all in the same direction around the tube (clockwise or ccw) do you split it up like 1,3,2,4 ?</TD></TR></TABLE>
As long as they're opposite quarters, it's ok... can be 4,2,1,3 if you want....about like how you cross up bolt patterns on a torque sequence.

 

Makes sense..the shrinkage is my main issue. And, of course, I only have this problem with stainless...the thermal expansion of this stuff is a pain. I haven't had much luck with the "do the same to the other side" method...guess I just need some more practice at it.

Here is what I'm thinking- design/build a runner in the fixture. While STILL in the fixture, weld out every pipe to pipe weld, but leave the flange to pipe and collector to pipe weld. Break that runner off and do the next one in the same sequence and so on. Once they are all welded out, put one on at a time an dweld it out. The tacks to the head flange and collector, if stout enough, should hopefully hold the runners in place...

 

also...if your pieces fit together NUT FLUSH. you wont have any warping because there is no where for it to go. try that. jsut remember that when you weld the runners on teh the collector you remember which runner went on which tube on the collector i welded my collector on 180 out...kinda fucked up the fitment. hhahaha

 

You can have two straight 6" sections of stainless steel tube fit up together perfectly and do a single pass butt weld over the joint. I can guarantee you that the resulting tube will be shorter than 12". Stainless shrinks .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by backpurge &raquo;</TD></TR><TR><TD CLASS="quote">You can have two straight 6" sections of stainless steel tube fit up together perfectly and do a single pass butt weld over the joint. I can guarantee you that the resulting tube will be shorter than 12". Stainless shrinks .</TD></TR></TABLE>

I agree. It is unavoidable. Carbon steel will shrink also, but not near what stainless will. If you have 16 ga stainless, it will typically shrink 1/16", depending on the welder (heat, speed, etc).

 

2nd gen 3sgte mani?

 

Dont mean to thread jack but, does that plate that the head flange connects to work well enough to prevent warping? I have had flange warping issues in the past from welding and am not too sure how thick this "plate" should be.

 

RTernie-like I said, the jig eliminates that from happening. I was smart enough to mark the "out" side of the collector. 1 runner did not fit together "nut flush"(but very close), but the rest did..Hence, all but one shrinking and not warping.

Javier- Yes sir..get the flanges from you guys too. Is it just me, or do you rmanifolds come with machined flanges? Here is a complete version of the mani...

CHB- It is 3/8" plate...pretty stout. I do all my manifolds on a 3/8" or 1/2" sheet, and I have never had a single problem with flange warpage. Not enough heat will transfer through the flange to the plate to even phase it...

 

the b series flanges are the only ones cnc milled at the moment. all others are cnc laser/water jet/flame cut etc. they are all machined after fabrication though

 

This completed manifold picture you posted up--is that the final product after welding each runner completely (sans collector and head flange), breaking it off, and then going to the next? If so, nice job!

 

looks good. i gotta build one of these for my buddies MR2 *( that bitch)

 

91tsiguy- No, I did that manifold the same as this...as much welding as I could get to, and the broke them off to finish them up. I spent 2 days(no rush, for a buddy) welding one or two here or there, so there was no problem on that one...here is the one I just finished.