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Discussion in 'Engine Building' started by 22crazy, Jun 9, 2004.

  1. 22crazy

    22crazy Senior Member

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    I was just wondering what makes a good header? I dont mean by company, i mean by design. Like the length of the pipe of each port, 4-2-1 design, 4-1 design, diameter of the pipe, size of the collector. Things like that. I see the race header from ericks racing and it have all these bends, what purpose does that serve? i will appreciate any input. thanks.
     
  2. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    There are a few links to very lengthy articles that just barely scratch the surface of header design if you just search some.

    All the bends in the newer race headers allow you to have longer primaries- if that's what you want.
     
  3. radnulb

    radnulb Senior Member

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    a good header flows well. bottom line.

    As for 4-1 vs 4-2-1: 4-1 generally produces more top end, 4-2-1 more low+midrange.

    Most of the difference between a $1200 and $400 header can be summed up by tuning. The more expensive headers pay a lot more attention to the length vs diameter of pipe (and often change diameter of pipe gradually) in order to try to preserve as much exhaust gas velocity and therefore increase exhaust gas flow. "Scavenging headers" are designed to use the velocity from the last exhaust gas pulse to pull exhaust out of the combustion chamber. The precise engineering behind these tricks is over my head.

    Ask all the thermodynamics bitches here for a sermon on promoting flow - they could do it far better than I could. :)
     
  4. 22crazy

    22crazy Senior Member

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    do u know where i can find information about it? i tried to search on the net, no real explaination...just pics of ones u can buy and the company....
     
  5. JDMilan

    JDMilan Senior Member

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  6. K2e2vin

    K2e2vin Senior Member

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  7. K2e2vin

    K2e2vin Senior Member

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  8. nismogod

    nismogod Senior Member

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    also, goto prespeed.com and look at their header. twisty. lol. equal length primaries are, to the best of my knowledge, better then unequal length. they cause less turb in the exhaust itself, hence meaning better flow. same idea as an atmopheric dump for a waste gate, vs. a exhaust dump @ 90degree perp to the exhaust pipe.
     
  9. MikeBergy

    MikeBergy Blah blah blah....

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    LOL. No sermon from me... I am still learning this stuff, although I am sure scavenging has a LOT to do with the dynamic pressure, of which air velocity is a main ingredient. Regarding the tuning of the pipes, it also depends on how much your exhaust ports are capable of flowing. If you have really large primary tubes, but your head is not capable of flowing enough air that your tubes on the header are designed for, you just wasted your money on something that will probably hurt the car performance more often than not. It's the same concept as having a turbo so big that your exhaust gas can barely spool it.

    Oh yeah, you can't really have power everywhere, so make a decision on what you want to get out of the car before you sink a ton of money into random parts. Just giving some food for thought. SMSP is a header designed for top end power, similar to a 4 into 1 header; in fact, if I am not mistaken, it is just a really long and twisty 4 into 1. So it is not the magical cure all header for everyone.
     
  10. nismogod

    nismogod Senior Member

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    i remember thermo in college. i miss all my physics courses. ::sigh:: o well.
     
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