Turbo headers: mild steel or stainless

[Matt@RFR]

i dont have the ability to back purge the material to weld stainless...

If that's the only thing holding you back, go to your friendly local hardware store and rig yourself a Y-fitting off of your regulator, with a ball valve in the purge line. That's not the preferred way to go about a purge line, but it works. The correct way, if you're wondering, is with two bottles and two regulators.

[myclone]

Use 347 filler and preferably tri-mix gas and don't look back. As with TIG, you will have to purge the inside of the tube.

Matt,

Ive never tried to do any SS MIG work and was wondering if you have any suggestions on where to start with heat/wire speed/torch speed/sheilding gas CFM/etc.

I cant ever seem to catch a nice TIG in my price range when I have the money and the situation at work has changed in that I cant use their TIG anymore but I already have a nice MIG in the garage I wouldnt mind giving it a shot to see how it turns out. Some input from someone thats already BTDT would be appreciated to maybe help with the learning curve though.

BTW, if you'd rather not hijack the thread with welding info feel free to PM me but I bet the ppl who are reading this thread would be interested in any info as much as I am.

TIA

[Matt@RFR]

I think the biggest problem you'll face is just the fact that you'll be welding 16ga butt welds with a MIG, stainless or not, in a small tube weldment. Your travel speed will have to be up there, and your fitup will have to be near perfect.

Definetely use .023" wire! ER308 for 304 tubing or ER347 for 321 tubing.

If you have a machine that has voltage and wire speed displays, I think I would start at around 13.5V and 135IPM. That's a wild guess, as I don't do much thin stuff with MIG.

You'll be looking to get a setting that obviously doesn't burn through, but that does produce 100% penetration. You'll also be looking for some color in the weld. Any welds that are flat grey, and you've lost all of the material's corrosion resistance, and have a very brittle weld. That condition on a header is a garunteed failure.

Unless you'll be using a spoolgun with a two stage trigger to post-flow the weld, the ends of each weld will turn flat grey. It's just a fact of life with MIG on stainless. (Also one reason that MIG on 4130N isn't recommended.) For the intermidiate stops along the weld, immediately brush the weld with a stainless steel wire brush used for nothing other than stainless, until the weld is silver. Do this while it's still hot! When you start your next weld, be sure to whip back onto the end of the previous weld, then continue regularly. This technique is kind of a band-aid, but in reality I've never had a failure doing it this way. To my knowledge, the city of San Fransisco's stainless drinking water filters that I welded are still doing fine.

Don't be surprised when the filler transfer sounds different than you're used to hearing. Stainless has a softer sound to it by nature, and I have a hunch that with the voltage/wire speed it will require, you'll be in what's called globular transfer. If that's the case, you'll see the end of the wire ball up and then drop into the weld.

[myclone]

Simply awesome...exactly what I was looking for.

Thanks Matt

I think the biggest problem you'll face is just the fact that you'll be welding 16ga butt welds with a MIG, stainless or not, in a small tube weldment. Your travel speed will have to be up there, and your fitup will have to be near perfect.

Definetely use .023" wire! ER308 for 304 tubing or ER347 for 321 tubing.

If you have a machine that has voltage and wire speed displays, I think I would start at around 13.5V and 135IPM. That's a wild guess, as I don't do much thin stuff with MIG.

You'll be looking to get a setting that obviously doesn't burn through, but that does produce 100% penetration. You'll also be looking for some color in the weld. Any welds that are flat grey, and you've lost all of the material's corrosion resistance, and have a very brittle weld. That condition on a header is a garunteed failure.

Unless you'll be using a spoolgun with a two stage trigger to post-flow the weld, the ends of each weld will turn flat grey. It's just a fact of life with MIG on stainless. (Also one reason that MIG on 4130N isn't recommended.) For the intermidiate stops along the weld, immediately brush the weld with a stainless steel wire brush used for nothing other than stainless, until the weld is silver. Do this while it's still hot! When you start your next weld, be sure to whip back onto the end of the previous weld, then continue regularly. This technique is kind of a band-aid, but in reality I've never had a failure doing it this way. To my knowledge, the city of San Fransisco's stainless drinking water filters that I welded are still doing fine.

Don't be surprised when the filler transfer sounds different than you're used to hearing. Stainless has a softer sound to it by nature, and I have a hunch that with the voltage/wire speed it will require, you'll be in what's called globular transfer. If that's the case, you'll see the end of the wire ball up and then drop into the weld.

[Matt@RFR]

Any time.

[shmoov69]

Mild is fine, stainless is better though. HPC (and others) makes a super high heat coating for the pipes that holds up to 2200*. I have had mine at egt's of over 1600* and the coating is just like new. I have also had the EGT's at 1480* from Dallas to Tulsa about the whole way on the PT 2 years ago. The timing slipped and I did not know it. Actually the balancer about came off too!
I went with mild almost 5 years ago because I did not have the extra jack laying around to do stainless. They are still great>(me knocks on wood!!).

[RobM]

did you use any specific header kit for your turbo headers jimmy? im not looking to build turbo headers but i am looking to build some custom headers for a NA motor. I figure if the stuff you used is good enough for a turbo then it will be plenty for what i need.

PS: if you have any other pictures of your set up im very interested in seeing them as i am more fasinated with your build then any of the high dollar high glamor builds that ive seen.

[shmoov69]

Thank you for the compliments! I do appreciate it. The "kit" is a box of 'U' bends that I got from Jeggs and the flanges from an old set of junk headers that I had laying around. A buddy of mine actually made them for me. My mind does not work that way! I don't think that I could start from nothing and end up with anything worth a crap! :rolleyes5
My main reasons for doing what I did with the car is that first, I had not seen any twin turbo'd street cars around at the time that I did it. Not saying that I was the first, but I had not seen any in the mags or anything like that other than a few of the mustang guys. Second, EVERYONE told me that a carb would not work, I must have fuel injection. Granted FI is much better, but carbys still work pretty dang good! Third, I had a goal to do it on the cheap (mainly because I had no dough to do it any other way!). Lots of used and junk parts to get it together and going. And surprising enough, the junk stuff lasted longer than the "good" stuff!.
PM me with Q's you got about my set up.