RabbitShit

Mind sharing a little about your setup for those welds? Tungsten, amperage, cup, flow, filler, etc. I'd like to find out how far off I am... outside of the crazy skill.

Engloid

I know nothing about BMW stuff. I just did the piping. The car belongs to a local guy.

The tungsten, gas flow, and all that stuff isn't all that critical, as long as you have them within a workable range. I really pay little attention to it, especially the amperage. I just turn the machine about half way up (400amp machine) and use a pedal or remote finger control.

Argon was probably at about 30cfh. I nearly always use 3/32 2% tungsten. The only time I use larger is when I'm melting the 3/32. I NEVER use 1/16" tungsten unless I'm welding somewhere else and that's all I have available. I don't even keep any of it at home.

RabbitShit

Pretty much exactly what I wanted to know. You use the 3/32 on the thin stuff for the downpipe too? Skillz!! What size filler are you using for the downpipe? That's a super nice, and fairly wide (relative to what is usually done) weld for such thin material.

Engloid

I have used 3/32 tungsten for material as thin as .006" (stainless). It was what I preferred, not a matter of all that was available. The bottom line is that you only use the very tip, and can sharpen it how you want. By using 1/16", you only reduce the diameter of the part that has nothing to do with the weld anyway. Not only that, but the 1/16" doesn't handle as much amperage and will not stay sharp as long.

For filler on the downipe, I use either .035 or .045, adding only a very minimal amount of it. A weld that's flush on the inside and outside is stronger than one that has reinforcement on it. I know it sounds crazy, but it's true. The bead isn't all that wide, but by having a wider bead on the outside, it gives a wider bead inside...which increases the ability to melt the actual seam on the inside. You can actually fuse this type of material with pretty good luck, but the fitup has to be closed up well. Too much heat will push it in where you get underfill. Too little heat can cause you to not break down the inside. And of course speed changes are relevant to this also. What I'm getting at is that you can fuse this material and have a sound weld with good strength, but only if you do it without overheating it.

I'd rather make three downpipes out of tubing than do one manifold out of pipe. Tube is much easier to cut, fit, and weld.

BoosTedZSix

ive only nigged once. but thats all that matters right? :P