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Thread: 321 Stainless Headers.... Help please!!!

  1. 31st July 2013, 05:36 AM #1
    justfishing Guest

    321 Stainless Headers.... Help please!!!

    Hello,
    Basically looking at building some headers from 321 stainless for my TD5, been looking and found this :
    Primary Header Tube Length and Diameter Calculator

    So stuck on these listed below.
    1. Exhaust valve duration
    2. Exhaust valve center line
    3. Volumetric Efficiency
    4. Exhaust Valve Opening Point is given in degrees before bottom dead center (BBDC)

    Any help would be great as no point building something that is not right. I do have VNT on my TD5. I do know that the power gain might not be great, but in all anything to make the engine flow better and run smother must be good for it lots of little things do add up. I have seen a photo's of Lara's on his Defender also of the IRB one, this would be fairly easy to build, but would prefer equal length
    Not unless somebody knows the dimensions already as in length and diameter.
    Thanks
    Ian
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  2. 31st July 2013, 06:50 AM #2
    rick130's Avatar
    rick130
    rick130 is offline Moderator Gold Subscriber
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    I have Smith's book that those formulas are based on, and his conclusions were cut and try and test on the dyno


    All a formula will do is get you in the general area. (which is great start compared to guessing) but the big problem we have is there is a massive restriction right at the collector outlet called a turbine which along with the different manifold temps I'm guessing may change the frequency the sonic pulses travel at compared to an NA engine.

    I'd have a read here too Burns Stainless LLC - Technical Articles

    and this is interesting
    Fabricators are tempted to run short stubby runners into a log or into a flange rationalizing that the short runners will minimize spool time and turbo-lag. In reality, the short runners are prone to cracking due to thermal expansion and the turbo response is terrible. Longer tube headers (between 15" and 25" runner length) improve turbo spool time, provide better boost and are less prone to cracking. The long tubes can be configured with bends which helps alleviate thermal stress.
    from here Burns Stainless LLC Technology - Turbo Headers
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  3. 31st July 2013, 02:42 PM #3
    Ancient Mariner
    Ancient Mariner is offline Wizard
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    While 321 would be the best grade I think you will have trouble sourcing bends and plate where as 316L will be more than good enough and readly available Duck over to the Isuzu section check out 4bd1 sizing and performance prediction
    Some discussion on manifolds from about page 12

    AM
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  4. 31st July 2013, 09:05 PM #4
    justfishing Guest
    Hello,
    Many thanks had a look but mostly on the turbo's didn't see any dimensions for the header.
    321 bends and pipe is quite good deals Exhaust Components - SPD Home Page B and reasonable freight costs, measuring the exhaust port it is square approx 25 mm by 30 mm so a in between maybe ?? I found a article that square pipe is better, as in gaining HP, as for length will do more research and go from there, getting the answer to the first link would take the guess work out of it. Stainless 316 would crack very quickly and as can not with stand the constant heat anything much over 900 C not good for it.
    Ian
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