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Lau Christophersen · Joined: 17 May 2013 Posts: 123 Location: Denmark/Copenhagen

Simple question; which kind of stainless steel do i have to use for a new downpipe from the turbo?
Is 304 stainless steel hard enough for the heat coming from the engine or?
My local smith do not know it and asked me to find out before he starts on my new exhaust he was talking about some kind of "tempered stainless steel".

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Surely gets 1000+...
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Paul · Posted: Wed Sep 10, 2014 10:31 am Post subject:

Based on this and the fact I've seen our turbos glow red in daylight, I agree.

http://www.hearth.com/talk/wiki/know-temperature-when-metal-glows-red/
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

304 is the cheaper stainless used for exhausts, 321 is better. Inconel is what Porsche used, its more expensive though.

Lau Christophersen · Joined: 17 May 2013 Posts: 123 Location: Denmark/Copenhagen

Thanks for your answers. Do you guys know if there are any places where I can buy a 3" downpipe(76mm) for the 931?
It is just for checking the prices it dont need to be stainless steel but the custom one i was asking my Smith to make will be around 1200$ for pipes and Work so i want to check some alternatives before i order it.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Is there a reason you don't like the factory piece? Surely one of the nicest you could get.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Lau Christophersen · Joined: 17 May 2013 Posts: 123 Location: Denmark/Copenhagen

Just because the rest of the exhaust system is in 76 mm pipes, and i thought that it would be best to make it the same size directly from the turbo.

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Downpipe ends prior to the cat. J-pipe may very well be the same material. . .sorta has that feel.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

The down, j, and dump are inconel. The flanges are steel. You should use a 625 rod to weld inconel to dissimilar metals (stainless, carbon & low alloy steel). Using regular steel wire will likely crack. The next best thing to inconel for turbocharged & high heat applications is 321 stainless. 304 stainless is better than plain steel but not great for high heat.