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308 Factory Exhaust Header Alloy

Discussion in '308/328' started by chipkent, Nov 29, 2009.

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  1. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #1 chipkent, Nov 29, 2009
    While pulling the engine from my 308, I found a nice hole in one of the exhaust headers. Some previous mechanic seems to have done a terrible job with a wire fed welder filling in the thin spot. I'm tired of bleeding cash with the engine rebuild so I'm probably just going to weld up the headers I have. They are magnetic so I assume they are either steel or a 400 series stainless alloy. So that I use the right filler and patch material, does anyone know roughly what alloy was used to construct the headers?

    Before charging ahead welding up the stock headers, are there any after market headers that are reasonably priced?

    Thanks for the help.
     
  2. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #2 chipkent, Nov 29, 2009
    In case it matters, my headers are the euro version which are not wrapped.
     
  3. CliffBeer

    CliffBeer Formula 3

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    #3 CliffBeer, Nov 30, 2009
    Chip, Superformance in the UK has about the most reasonably priced headers available. Very nice quality. http://www.superformance.co.uk/a-308/exhausts.htm
     
  4. AZDoug

    AZDoug Formula 3

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    #4 AZDoug, Nov 30, 2009
    312 stainless Tig rod is a good choice for welding about anything so as not to get unwanted hardening of the weld on unknown steels.

    Doug
     
  5. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #5 chipkent, Nov 30, 2009
    Thanks for the filler rod suggestion. I also have to make a small patch. Do you have any recommendations for the patch material?
     
  6. AZDoug

    AZDoug Formula 3

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    #6 AZDoug, Nov 30, 2009
    304 stainless sheet.

    I use the 312 rod a lot when I have to weld 300 series to 4130 steel or steel of unknown origin, especially if it needs to be machined later, as usually welding stainless to mild steel or high carbon steel results in some nasty hard weld grain precipitation if you use 308 rod or E70S2, the 312 minimizes this. The factory pipes are probably 400 series, so the 312 should work fine here also.

    The 312 is also a good filler rod for welding mild steel to mild steel, if a proper mild steel rod can't be found.

    Doug
     
  7. BigTex

    BigTex Seven Time F1 World Champ
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    #7 BigTex, Nov 30, 2009
    Be sure to inspect them carefully, if they blow apart it sets your fan belts on fire...:rolleyes:
     
  8. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #8 chipkent, Nov 30, 2009
    So that all of FC will know what the actual factory header alloy is, I'm going to send a piece that I removed to a friend with access to a magical x-ray fluorescence device that can give the elemental composition.

    Anyone know what alloy the superformance headers are? Are they an alloy that will stay looking good without ceramic coating or paint, or will they start rusting like the factory ones?

    In addition to the hole I need to weld up, about half of the heat shield bolts broke off on me. I had the guy at the machine shop take a look at it when dropping off the seals for my heads, and he thought it would be $250-$350 in labor to fix them (At $88/hr). He also felt that ceramic coating alone wouldn't be enough to keep the under hood temps down properly. I have my own milling machine so I could fix the heat shield bolt holes. ...so it looks like there will be some balance between shelling out more cash for new headers and getting off my butt and doing some milling and welding to fix the old ones.

    Has anyone put a lot of miles on a car with ceramic coated headers and no heat shields to comment on the machinists comment about ceramic coating not being enough?

    The machine shop should get to my heads this week. At that point, I'll know how much green I've had to bleed for them. If they aren't too bad, I may just order the new headers.
     
  9. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #9 chipkent, Nov 30, 2009
    BigTex, any idea where things start going bad before the headers self destruct?
     
  10. PhilB

    PhilB Formula 3
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    #10 PhilB, Nov 30, 2009
    Re: the Superperformance headers, I spoke with the guys at Superperformance about 4 weeks ago and they advised that for US cars with exhaust analyzers, their headers don't come setup to receive the analyzer pipes.

    This may be a problem for some folks who have the stock emissions equipment, certainly on QV cars, not sure about injected..

    Phil
     
  11. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #11 chipkent, Dec 4, 2009
    My friend did the x-ray fluorescence testing on the chunk of euro header I sent him. It is 98% iron. so it is probably 1018 steel or something similar. Contrary to the rumors, the factory headers are not stainless of any kind.
     
  12. BigTex

    BigTex Seven Time F1 World Champ
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    #12 BigTex, Dec 4, 2009
    I did not think so.......

    Mine blew out at the 4 into one collector, at the horizontal 90 towards the rear, in the front bank.....flame was right into RH fuel tank at that point.

    My engine had been "single bank firing' due to ignition problems, the equivilent of filing it with raw fuel, then the MSD would reset and blow flame about four feet out the tips....

    A running pipe bomb.

    The rears went, not long after the fronts. They would normally last a lot longer of course.

    Ceramic coating will not effect underhood temps much but recall the heat cladding was to TRAP heat, not dissipate it...they were trying to continue to oxygenate the unburned HCs.

    I'd say a repair would be fine, but cracks are cracks and it's so much work to change them 'engine in" I'd give long thought to some fresh ones..

    Front used was $250, rear used, not so lucky $700...this was years ago.

    Mine is a NON CAT car.....
     
  13. BigTex

    BigTex Seven Time F1 World Champ
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    #13 BigTex, Dec 4, 2009
    One night a girl following me could see the aluminum cladding melting and hitting the ground, as I drove...how hot is THAT?????

    Goes bad quickly if fuel mixtures are not right....
     
  14. chipkent

    chipkent Karting

    Jul 16, 2009
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    #14 chipkent, Dec 4, 2009
    The weak area of mine that I'd have to fix is exactly where you describe. The cam covers had a nice exhaust soot covering from the leak. Since the factory headers are not stainless, that gives me another reason to replace them. I should get my heads back next week (3rd "next week" so far). If the damage isn't too bad, I'll just get the new ones.
     
  15. Sean F.

    Sean F. F1 Rookie

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    #15 Sean F., Dec 4, 2009
    I just sent my headers off to Jet Hot to be coated. I used them on my FF2000 car and they do indeed keep things much cooler than the heat sheilding, not to mention things flow a lot better as well.

    The headers are not steel, at least mine are not magnetic so they are some kind of alloy of Stainless. Interestingly, the flanged ends for bolting to the head and muffler are magnetic. They had some light rust on them, but the headers off my car were very clean.
     
  16. ramosel

    ramosel Formula 3

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    #16 ramosel, Dec 4, 2009
    Last edited by a moderator: Sep 7, 2017
    At what area did you do your sampling? On mine, the flanges and collector ends are magnetic where as the tubes are not. The flanges and collector ends have a different spark type when you grind on them than do the tubes. The flanges and collector ends are rusted, the tubes are not. So while I'm inclined to believe parts of my headers are plain steel, the tubes are not.

    I just finished hacking and welding on mine so they can go out for ceramic coating.

    Oh, and THANKS to whoever recommended the 312 rod... worked wonderfully!!!
    Looked back... Thanks DOUG!!!

    Rick
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  17. CliffBeer

    CliffBeer Formula 3

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    #17 CliffBeer, Dec 5, 2009
    Phil, very good point.

    I don't believe my car has the analyzer pipes. But, I seem to recall seeing them before on other 308s - basically it's a small diamater pipe threaded into a port on the header, with all the pipes coming together at a collection point somewhere on the bulkhead wall, is that correct? What are you the analyzer pipes used for?? Checking indivdiual cylinder mixture/emissions???
     
  18. ramosel

    ramosel Formula 3

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    #18 ramosel, Dec 5, 2009
    Not the bulkhead wall but near the dizzys on each head. At some point my car lost its analyzer pipes - Factory/PO/who knows? In their place, someone had crossthreaded coarse thread screws into the tube bungs and snapped them off... If I was ever going to make it right, I was going to need new headers anyway. That's why I just cut the shielding and the bungs off and tigged the holes up.

    Rick
     
  19. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #19 chipkent, Dec 7, 2009
    The metal sample I sent my friend was from near the collector on the bottom end. It was the section with the rusted hole that I removed. My entire header is magnetic. Looking at your picture, I notice a few differences: 1) lack of rust and 2) your plates that mount to the head are joined while mine are not (at least I don't remember them being joined). I'm wondering if the factory changed the headers over time or if things were changed on my car when it was imported to the US. My rear header has a port for an O2 sensor. Did the factory euro headers have an O2 port? Were the ports on the factory headers always joined?
     
  20. PhilB

    PhilB Formula 3
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    #20 PhilB, Dec 7, 2009
    I think these pipes are part of the Air Injection system, in use when the car is cold. When cold, the check valves open and air flows direct into the headers, presumably to reduce emissions as their is more unburnt fuel in the exhaust gasses when the car is cold.

    This is my understanding, I could be mistaken,
    Phil
     
  21. chipkent

    chipkent Karting

    Jul 16, 2009
    115
    #21 chipkent, Dec 7, 2009
    There are air injection ports which I have seen on either the head or the headers (head in my case). There are also measurement ports where some sort of instrumentation can be attached. These are lower on the headers.
     

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