OEM exhaust shorty "headers" material

[Robottrainer]

Anyone know what material and guage the stock oem headers are made of? I suspect 409 since it rusts. Going to weld a 3/8 flange onto the drivers side. Just getting the fill wire and welder settings sorted out.

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[engineermike]

I believe it to be 4xx ferritic stainless, probably 16 gauge. I’ve welded it to austenitic using 309L wire MIG using tri-mix gas. Technically I think the backside is supposed to be purged as well but I’m not sure that matters that much for what we’re doing.

 

[Robottrainer]

I believe it to be 4xx ferritic stainless, probably 16 gauge. I’ve welded it to austenitic using 309L wire MIG using tri-mix gas. Technically I think the backside is supposed to be purged as well but I’m not sure that matters that much for what we’re doing.

Back purging is desirable, but yes, I don't think it's necessary for something like this. I havent decided If I will just tack it and get my buddy to tig it, or bite the bullet and mig it by welding short sections at a time so I don't overheat/burn through. I can get tri mix but it's Argon/oxygen/CO2.

 

[GregO]

Solar Paste is an option. https://www.harrisproductsgroup.com/en/Products/s0fb01
You didn’t mention the material of your weld flange ?
Machining an aluminum or copper ID plug is another option. It will act as a chill and help reduce weld oxidation by displacing oxygen at the weld joint.

 

[Robottrainer]

Solar Paste is an option. https://www.harrisproductsgroup.com/en/Products/s0fb01
You didn’t mention the material of your weld flange ?
Machining an aluminum or copper ID plug is another option. It will act as a chill and help reduce weld oxidation by displacing oxygen at the weld joint.

Flange is 304. Yes, I thought about the plug route. I'll have to do some weld test to see what setting works best. I don't want to blow away the thin material or have snot hanging down on the I'd of the header

 

[Robottrainer]

Flange is 304. Yes, I thought about the plug route. I'll have to do some weld test to see what setting works best. I don't want to blow away the thin material or have snot hanging down on the I'd of the header

Correction. I just did the magnet test. The flange must be chrome dull chrome plated 4xx stainless or mild steel. Tough to tell with the plating but it is magnetic. I do know the supplier of the exhaust pipe used the same flange on their 304 stainless pipe.

I did have two 304 flanges made but not very happy with how it was made (center hole is off a bit). I could take carbide to it. The stuff is hard.

Opinion: should I use the 304 or the unknown flange that was machined correctly. I'd Image 308L wire would be best for the ferritic stuff.

 

[GregO]

Opinion: should I use the 304 or the unknown flange that was machined correctly. I'd Image 308L wire would be best for the ferritic stuff.

You have some things to sort out.
The Tri-mix gas you mentioned has oxygen which will make a huge mess of alloys containing chrome/nickel/molybdenum.
Your concern for welding 18-16 ga. to a .375” thick flange w/o losing control of the weld puddle has merit. This is where a snug fitting ID aluminum chill is your friend. (Copper chills are to expensive for your application)
As far as flange material I’d choose 304 for two reasons, corrosion resistance and weld puddle wetability. Welding an unknown material is risky.

 

[Robottrainer]

You have some things to sort out.
The Tri-mix gas you mentioned has oxygen which will make a huge mess of alloys containing chrome/nickel/molybdenum.
Your concern for welding 18-16 ga. to a .375” thick flange w/o losing control of the weld puddle has merit. This is where a snug fitting ID aluminum chill is your friend. (Copper chills are to expensive for your application)
As far as flange material I’d choose 304 for two reasons, corrosion resistance and weld puddle wetability. Welding an unknown material is risky.

Finding Helium/Argon/CO2 mix around here is pretty tough not the mention they want you to sign a yearly lease for the bottle.

I found one company that will rent me a bottle on a monthly basis. This is what they said:

The mixture we have is a tri mix
91% argon, 5% CO2, 4% Oxygen
It will work on this stainless

my assumption at the time was 304/409 stainless.

maybe the better option is to tack the flange on using C25 and 309 wire and then having my buddy tig it.

 

[ZeroTX]

Y'all are speaking Chinese to me as a non-welder, but wondering why we're welding a flange onto the stock header? Doesn't the driver's side have a flange? Passenger side flange is after the cat, so I can see fixing that one and would also want a quality weld ,but would have to farm that out and no idea who to go to, because most exhaust shops won't cut a cat off.

 

[Robottrainer]

Y'all are speaking Chinese to me as a non-welder, but wondering why we're welding a flange onto the stock header? Doesn't the driver's side have a flange? Passenger side flange is after the cat, so I can see fixing that one and would also want a quality weld ,but would have to farm that out and no idea who to go to, because most exhaust shops won't cut a cat off.

Nope. 2015 to 2024+ has a flange on the passenger side and the cat welded onto the drivers side. Has to be cut off and a flange welded to it. Why? Your guess is as good as mine.

 

[ZeroTX]

Nope. 2015 to 2024+ has a flange on the passenger side and the cat welded onto the drivers side. Has to be cut off and a flange welded to it. Why? Your guess is as good as mine.

Oh ok, I had it backwards, and it still makes absolutely no sense other than to prevent owners from easily removing the cats. But then they would have done it on both? Weird.

 

[GregO]

no idea who to go to, because most exhaust shops won't cut a cat off.

Pipe fitter, specifically hygienic piping but most fitters have the skills to perform the work we’re discussing.

 

[engineermike]

…it still makes absolutely no sense other than to prevent owners from easily removing the cats. But then they would have done it on both? Weird.

They did it this way because the drivers side header is actually super easy to remove and replace.

 

[Robottrainer]

They did it this way because the drivers side header is actually super easy to remove and replace.

And it forces you to spend more money to buy both when one or the other has to be replaced

 

[engineermike]

My guess is that it saves them the cost of the flange and an assembly step while not significantly making it harder to service later. Most of the replaced ones will be under warranty anyway so they’d just be costing themselves more during every warranty repair. Someone probably did the math and ultimately determined it was lower overall cost by eliminating the flange.

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