#20 CK Cup set up for thin wall tube

adrynalinjunkie · Tue Jan 13, 2015 7:04 pm

I will be TIG welding 16Gauge .65" mild steel 2" pipe for my Turbo charger manifold on my Chevelle.

I ordered the HTP 221 and I also ordered the standard pyrex cup kit....(1/2" Dia cup)

What would be the best cup set up for thin material such as this?

I am thinking this Large pyrex cup kit would work better

http://www.usaweld.com/WP-9-WP-20-Serie ... -s/599.htm

Or does anyone have a better recommendation?

2nd Question.. I will be using 70S6 .035" filler rod, would a .040" Tungsten produce better results than a 1/16" Electrode?

3rd Question.. I am looking for strength (resistance to cracking) as this thing will get glowing red going down the race track... How many passes for butt welds on this .065" tube?

Would if be worth it to purge it?

Superiorwelding · Tue Jan 13, 2015 7:42 pm

I can give you opinion but there are others who will jump in as well.

1) I do not feel for carbon tubing that the pyrex cup set up in a absolute must. It is cool and I have them but you can just as easily use a gas lens and bigger ceramic cup. Just a cost saving thought.

2) I recommend ER70S-2 because of the less silicon content. The S-6 works well for MIG but is not necessary for TIG. It will not hurt in your application though, I don't believe. The .040 tungsten will allow you to focus your arc but will have amperage limits. I personally would use the 1/16" but either will work.

3) Keep in mind your heat input on your turbo piping. More passes does not guarntee more strength. You can actually do more damage by putting to much heat into the material than less. I would go with maybe a fuse pass and maybe one cover pass but I am not a turbo manifold builder either. There are others who can help with this one. I would recommend the purge as it seems most prefer this method and you will eliminate that ugly, restrictive root inside, at least if done correctly.
-Jonathan

brokeitagain · Tue Jan 13, 2015 8:18 pm

I don't believe that mild steel is the material of choice for this kind of project,

Tue Jan 13, 2015 8:33 pm

brokeitagain wrote:I don't believe that mild steel is the material of choice for this kind of project,

I don't believe there's a choice other than replacement, since the stock manifold is apparently carbon steel.

I wouldn't expect a long working life, and a replacement will be coming.

Or, his manifold is 400 series, thus magnetic, and he doesn't realize it's stainless...

Steve S

Oscar · Tue Jan 13, 2015 8:44 pm

how many passes for butt welds on 16 gauge mild steel for the hot side of a turbo manifold???? Am I the only one here face-palm'ing?

GreinTime · Tue Jan 13, 2015 8:55 pm

When talking to a teacher at school, if you pose the "stainless vs carbon" question to him, his answer is always: "How much do you want to spend?" For him, it was never worth the added cost in most cases to make a stainless thin wall header for a dirt car because it was going to get torn up, someone would wreck the car, and so on and so forth. From what he said (I have no personal experience with IndyCar) even in the turbo IndyCar days the manifolds were mild steel, and it wasn't until fairly recently (in the grand scheme of racing) that the upper echelons of racing switched to exotics like Inconel625 and the like.

My question to Adrynalinjunkie would be: Why so thin? Most turbo manifolds that see long term repeated success are made of sch10 or sch40 pipe. Thermal expansion is going to be your enemy, in addition to the weight of the turbo no matter what your manifold is made out of. If you're running a single turbo big enough for a Chevelle, it's likely a large piece of equipment. Make sure to brace it properly. Nothing spells a short service life for a turbo manifold that sees track use than a turbo just hanging there with the wastegates dangling off the manifold as well.

And to answer your question about welding the pipe, no, I don't believe back purge would hurt anything, but you are not welding a reactive metal, so frankly it would be unnecessary as far as I would be concerned. I prefer to weld with the large cups over regular ones, but I like to run as much stickout as feasibly possible. If you are making your own collector, it would likely be beneficial to have at least one large gas lens (FurickCup or Jumbo CK) to allow the stickout necessary to get into the center of the collector to weld it shut.

adrynalinjunkie · Tue Jan 13, 2015 9:33 pm

Otto Nobedder wrote:
brokeitagain wrote:I don't believe that mild steel is the material of choice for this kind of project,
I don't believe there's a choice other than replacement, since the stock manifold is apparently carbon steel.

I wouldn't expect a long working life, and a replacement will be coming.

Or, his manifold is 400 series, thus magnetic, and he doesn't realize it's stainless...

Steve S

There are alot of guys that run stainless...but alot of them have it crack

There are many, many, many guys that use mild steel, especialy in a case such as mine where the Turbo is hard mounted to the frame and the engine is solid mounted... I could post threads of guys that have MIG welded the mild steel (and not the best welds at that) and have been making major HP and doing fine...

The danger of MIG though is that some guys get welding splatter in the pipe, and then when it comes loose the (welding berry) locks up the Turbo compressor when it is spinning at 100,000 RPM ...and you can guess what happens after that. lol
Since turbo's are oil cooled you can end up oiling down the track, and potentaily your own tires (which is never good)

The beauty of Mild steel is that it does flex a little and is not prone to cracking the way stainless does..

You are correct though this system will most likely be torn up and modified for a bigger set up.

Cost is another factor of coarse, 321 stainless works best...

2 passes doesn't seam unreasonable, especialy if the 1st is just a fusion pass, but I am a rookie TIG welder!

GreinTime · Wed Jan 14, 2015 12:15 am

I guess what we're getting at man is that in no way shape or form is a second pass necessary on .065 wall tubing. You can easily achieve full penetration with a TIG welder and still have it be aesthetically pleasing.

Also, 321 stainless is sweeeeeeet if you can afford it. Burns is really proud of theirs if you've ever priced it out... ACE Race has some decent prices on stainless comparatively, as does Vibrant (don't remember if Vibrant stocks 321 or not)

brokeitagain · Wed Jan 14, 2015 12:48 am

turbo+ mild steel = wasted time. not starting a war but I have many people that think the ''lean is mean'' principle works for them. they never buy exhaust systems, turbos or manifolds. but changing pistons is like changing oil to them

Oscar · Wed Jan 14, 2015 12:59 am

brokeitagain wrote:turbo+ mild steel = wasted time. not starting a war but I have many people that think the ''lean is mean'' principle works for them. they never buy exhaust systems, turbos or manifolds. but changing pistons is like changing oil to them

I agree. Sch10 pipe, purge it, and be done. Not like it's that expensive. Besides, who in their right mind would even sell/build a mild steel turbo flange?