DanaT

I have found my exhaust leak. It is s cracked header.

Has anyone ever had chemical analysis (i.e. OES) done on a 951 header to determine what type of stainless the factory used when making the header? I would guess it is a 321 stainless, but that is just a guess.

Does anyone have any really trashed (i.e. non repairable) header (or section of header) that they would be willing to have tested to determine the metal?

I am thinking of having my header re-welded and just want to use the proper filler metal. I guess it doesn't matter that much, as a 347SS rod can always be used if it is a 321 or 304. Just finding a welding shop that has 347 can be much harder than having to use a cheaper grade of SS filler metal.

My other options are 1) find a good used 1-4 header or 2) buy a SFR header. I am just not convinced that the SFR headers are really worth the $$. Really, what will aI get with the stage 1 header? 10HP on a good day? Maybe a little quicker spool-up? Maybe slower spool-up? I would bet just fixing the exhaust leak on a stock header will help me out a lot.

-Dana

95ONE

I think i actually read somewhere it was INCONEL (Did I even spell that right? - funny, i used to sell it when I sold pipes and valves) It did weld up kinda funny. It did have sort of an aluminum type glaze over it. (the way inconel is suppose to weld) None - the - less. I doubt it, but I know I read it .....somewhere.

Sorry, almost a worthless post, but I haven't seen any other responses either!

And, don't worry about the filler rod. MINIMAL difference it price. or cost to the welder. If they are any type of decent company, they will have the proper one. I even have inconel filler rod!

I would just fix it. (If its the bellows type)

Ben Z.

I can take a look if anybody wants to send me a piece. Don't need much, just a few filings, stay away from any really oxidized regions.

aventari

My header is cracked on my 89 also.

I have a MIG welder with just regular wire in it, I'm planning on welding it up and seeing what happens. Would I *really* notice a difference with different filler wire?

ross255

Aventari

I have also welded the exhaust with regular mig wire, and so far no problems.

azmi951

Yes, the PO did that on my cross over. It fell apart.

951_RS

lol.... the stock headers are inconel, and you have to weld that differently. I would not use anything less due to the difference in cooling characteristics. Send it to SFR and they'll weld it for like 50 bucks (that's what they quoted me)

z3bra

It's not inconel it's 321 or whatever the DIN equivalent to 321 is. The flanges are 409 or the like since they're magnetic, but the tubes are definitely some kind of austenictic stainless with 321 being the most likely choice. I've welded mine with 347 filler rod just fine (well fine other than my welding skills leave a lot to be desired).

Welding inconel isn't all that different anyway, it's actually pretty similar to welding stainless, back purge with argon and TIG away to your heart's content. (Same goes for the factory 321 stainless tubes).

Also, if the factory parts were inconel, they probably wouldn't have cracked in the first place, but given the price of inconel at about $100/linear foot, for tubing nowadays let alone 20 years ago, I just can't see Porsche using it as the material for the header when on a factory car in the price range and market segment of the 951, 321 is more than good enough for the job for 10+ years of use.

Edit:

The original poster is right, 347 filler rod isn't something most places keep on hand because the need to use it isn't all that common. I've bought mine locally here from GHL exhaust, but they're about the only place in Phoenix that keeps it in stock and doesn't mind selling it in smaller quantities. If I want to buy 5+ lbs of it at a time, then I can get it, but that's more than I think I could ever have a need for.

I honestly think you could probably get away with using 316 filler if you absolutely can't find any 347 on the crossover pipe, but for the headers themselves, I'd stay stick with 347 rod.

hosrom_951

I had a small hole in the spring on header runner #1, the machine shop used some kind of copper filler to fill the hole. It was a very small hole though, they did not use the filler rod(s) used in welding, i can find out tomorrow what it is exactly if anyone cares .

No leaks after 3,000kms IIRC

z3bra

Hosrom, on the bellows you're talking about, you can probably get away with something lower temp, it's not directly in the path of the hot exhaust gasses. (There's a tube inside the bellows and they're more like a secondary cover of sorts). If I were to guess, it almost sounds like they might have brazed it and not welded it. Then again, sometimes stainless filler will look somewhat gold colored for a while when it's relatively new.

z3bra

Oh and I forgot, DanaT, if you can get it analyzed, I think I'd be willing to cut off a piece, I've got a so-so 1-4 I'm going to cut the bellows out of and put it on the #2 runner since that one seems to like to crack where the tubes meet. Actually I'm getting tempted to just buy some 321 tubing and build an new header using slip fit connections and ditch the bellows setup entirely. The "y" section of the 1-4 is really pretty nasty when you look at it w/o the insulative covers, it's two stampings welded together and seems like it's inclined to induce a lot of turbulence into the exhaust flow (or it certainly has the potential to do so at least). It's also a pretty wide angle for the merge, I've been told that 14 degrees is the optimal angle, and that thing's more like 60 degrees if not even more than that. It's almost as though the #4 enters the exhaust stream from #1 almost perpendicularly when it should merge in smoothly and as close to parallel as possible.

hosrom_951

Right, i just got off the phone with the shop, they said that they used a brass rod. They informed me that the technic is called brass bracing (or brazing as you said).

sm

z3bra:

As usualy, another knowledge-filled post from you. Thanks.