Why not to use cheap 304 stainless

[Dawson Performance]

When mine cracked I took to my uncles welding shop and teh guy that does his tig work said it was a bitch to weld back cause the metal was ranging from .045 to .050 thick. So the answer to how thick the steel is THIN

[Torqued]

It's always easy to post up a success story and not so fun to post up problems.  This is good information, a lot can be learned from failures.  Thanks for sharing your experience.

[Blue]

Interesting and thanks for the review.

[my8950]

So when you sold it to another guy looking for a turbo kit, did you tell him how much of a pile of shit it was? 

[domn8rx]

Yes i did.. that is why he got three headers and two crossovers. I also told him how much i paid to fix them the last time. He was sold on it when he knew it made 577rwhp on a 130k short block.

john

[lowdeuce]

What are peoples opinion on 304 schedule 10 which has a wall thickness of .109"?

Jared

[blacksaleen95]

What are peoples opinion on 304 schedule 10 which has a wall thickness of .109"?

Jared

Thicker 304 will probably do fine... schd 10 is very thick and should be ok....

Like it's been mentioned, you're better off sticking to mild steel unless you have the cash to do it with some good 321 SS.

On a stainless kit you can expect over time to have cracks show up here and there simply because of the material properties vs mild. SS is brittle and is prone to cracking, whereas mild has some flex and forgiveness to it.  I've used a few mild kits, and fabbed some mild kits and haven't had any issues.  A lot has to do with the construction of the pipes too...anyone can just weld some pipe together, but if the pipes are welded together already in a tensioned state you can expect for cracks and breaks to occur. That's why you're better off spending the $ on a reputable place if you can't do the stuff correctly yourself.

[Kerrdogg]

I'm not a welder but I'll argue against the use of 321 in a turbo kit especially when applied to a drag race type situation. My customers that build turbo kits for drag radial and 10.5 outlaw cars have told us repeatedly that the 321 is far to brittle and cracks very easily especially on any car that see's tire shake. My opinion is that 321 especially 18ga is useful for N?A cars that are looking for the lighest most durable exhaust material wihout getting into inconal. I would say the best alternative would be to stick with 304 SS with a decent .065 wall thickness, use bracing and proper welding techniques. The kits that I have seen built this way have lasted several years and performed well, mild steel unless coated inside an out can have rust issues especially if race or other exotic fuel types are used. I have seen a kit that looks fine on the outside have a pile of scale and rust fall out of it, just offering my views, been around this stuff for along time, heck even my factory Turbo Buick headers cracked back in 1989.

[Gen1SVE]

I'm not a welder but I'll argue against the use of 321 in a turbo kit especially when applied to a drag race type situation. My customers that build turbo kits for drag radial and 10.5 outlaw cars have told us repeatedly that the 321 is far to brittle and cracks very easily especially on any car that see's tire shake. My opinion is that 321 especially 18ga is useful for N?A cars that are looking for the lighest most durable exhaust material wihout getting into inconal. I would say the best alternative would be to stick with 304 SS with a decent .065 wall thickness, use bracing and proper welding techniques. The kits that I have seen built this way have lasted several years and performed well, mild steel unless coated inside an out can have rust issues especially if race or other exotic fuel types are used. I have seen a kit that looks fine on the outside have a pile of scale and rust fall out of it, just offering my views, been around this stuff for along time, heck even my factory Turbo Buick headers cracked back in 1989.

+1  All 3 of my .065" wall 304 turbo systems are doing well, 5 years on one, 50k on another, no cracks or repairs. It is all in the thickness (not the grade) of the material, the welding technique, and viabration isolation (includes the brackets) used to assemble the kits.    Ever wounder what filler material is used tio weld the chineese kits?   

[sceric]

i am sooooooooooooooo glad someone with first had experience took the time to break this down for me esp. you always hear the stories about things like this but to actually see the pics really makes everything else believable.

[Stangguy]

Corrosion Resistance

Equivalent to Grade 304 in the annealed condition, and superior if a weldment in these grades has not been post-weld annealed or if the application involves service in the 425-900°C range. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C. Considered resistant to potable water with up to about 200mg/L chlorides at ambient temperatures, reducing to about 150mg/L at 60°C.
Heat Resistance

Good oxidation resistance in intermittent service to 900°C and in continuous service to 925°C. These grades perform well in the 425-900°C range, and particularly where subsequent aqueous corrosive conditions are present. 321H has higher hot strength, and is particularly suitable for high temperature structural applications.

[Stangguy]

go here for more info

http://www.azom.com/details.asp?ArticleID=967

[CarolinaCat]

Im with Kerrdog I wont have a mild steel kit.  The last kit I had ate it self up from the inside out.  It was Not coated on the inside.  You could take any piece of the hot side and tap it on the ground and scale would fall out.  It looked like the piping had been in the ocean.  I ONLY ran 110 fuel in the car no pump gas and only drove the car once or twice a month.  I believe if the piping had been heat cycled / driven more that would of help keep the rust down.  In a matter of three years I had holes thru the bends and I totaly redid the whole hot side before i sold it.  I would say mild steel Needs to be coated inside and out and pretty much no race fuel ran thru it.  Stainless needs to be the thicker the better and i would use header wrap to help hold the heat in it or have it ceramic coated as well.

[jayson]

same headers... same problem.


I would post pic but right now its about -2*F and there is 3 ft of snow ontop of the car lol

[wildcardfox]

304 stainless I've never had a problem with it in any of my kits. Design is key... Stainless expands in the design of the kit and where the turbo is mounted it looks to me like a crack do to stainless expansion and the fact that the turbo bracket restricted any growth thereby ending in a stress crack. Swages should have been used in the design. That is what I notice in that kit.. Problems in design.

[ShaneH]

304ss is not the problem here. It's the choice of 304ss and the welding. I've seen those same headers crack before and when I took a look at them, even though they were advertised as 16 gauge, they were closer to 20 gauge.  Plus, they were not backpurged or solar flux'd. Those two things right there are what causes the issue. With the application we're talking about here, any header material would have cracked had the gauge been that thin with no backpurging. 

[livefast1]

wouldn't the fact that the majority of the cracks are on the welds. this one point the issue that the welds weren't back gassed.

[mustangcobra438]

they dont use the correct filler metal either in the cheaper kits and that as well as the metal being too thin would cause the cracking in the high heat enviroment. Either way ill build my own before i would buy any ss ''kit''. Thanks a lot for the thread, i think it will be vary useful so people can be aware. What sucks is that is was at your expense.

[domn8rx]

It sucked from start to finish, the money was the easy part, it was just all of the wasted time. I have less money in my kit now, no cracks and we have fun driving it. Thats all any of us want to do, spend our hard earned money and drive our car....why is that so hard sometimes.

john

[NWJason]

is this the same steel that pny down uses on their kits?

[domn8rx]

I didn't think pony down used stainless??

john

[mustangcobra438]

i thought pony used 16gauge mild steel?

[10secgoal]

the thickness is a big role it in. There is another though. Jon may be able to take a closer pic. All this over seas stuff is a dead give away, and not because it's shiny. they pulse weld it, and they get it too hot. They always undercut the shit out of the material they are welding. pretty much means they are drawing material from what they are welding into the puddle, and the adding rod after it gets hots. That makes the edge of the weld VERY thin, it's already weaken because it was welded, then when 304 expands as much it does, crack. The 321 does better than the 304 because it's expansion rate is much closer to mild steel.

[1BadV6ThirdGen]

im surprised with all this talk that noone has mentioned 316L stainless

when i reasearched a few years ago on what to build my headers out of its come down to 321 stainless or mild steel.

i wanted to do stainless so it wouldnt rust up and stainless holds the heat inside the tubes better.
well i couldnt afford 321 stainless so i looked into 316 stainless

316 is a lil iffy to use but is still better then 304, then i cam across 316L which has better properties and can withstand higher heat

i built my headers 2 years ago out of 316L stainless and 321 stainless flanges. its all .065 wall stuff,

316L is fairly inexpsensive and it works great, i havent had any issues with cracking, and i dont even run a flex pipe on my crossover.
what i did is make the headers/flanges out of stainless and used a mild steel crossover

opps forgot to add i belive i welded it all together with 308 wire but id have to dbl check on that

[gotageta5oh]

you get what you pay for.........