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Long tube headers, which Primary size is 'best'?

Discussion in 'Exhaust' started by [email protected], Apr 7, 2015.

  1. PaleRider

    PaleRider Death Spank Established Member

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    I'm interested in a 1⅞ to 2 inch step header.
     
  2. gt5.0coyote

    gt5.0coyote Well-Known Member Established Member

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    Second this. Never had an issue with the pypes longtubes. Fitment is/was excellent!
     
  3. gt5.0coyote

    gt5.0coyote Well-Known Member Established Member

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    Does pypes make a set of longtubes and shorty mid pipe for the 15+ v6?
     
  4. noldevin

    noldevin Active Member Established Member

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    Did you even read this thread? lol
     
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  5. PaleRider

    PaleRider Death Spank Established Member

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    Yes, of course. I had waited over a year to even post in this thread. So what did I miss?
     
  6. noldevin

    noldevin Active Member Established Member

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    I just have a hard time figuring out why anyone would want 2 inch headers, stepped or not, after reading this.
     
  7. Weather Man

    Weather Man Persistance Is A Bitch Premium Member Established Member Top Shelf Gentlemen

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    If they thought they might go F/I over 800 HP later, I could see buying headers once.
     
  8. noldevin

    noldevin Active Member Established Member

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    People in this post are over 1000hp on 1-3/4 headers
     
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  9. beefcake

    beefcake Authorized Vendor Authorized Vendor

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    doesn't mean you can't pickup with more

    on a "blower car", especially over 1000 wheel, and higher, you really almost can't get the air out quick enough

    fastest s/c coyote out there mid 7s with 2 to 2 1/8 to 2 1/4 stepped

    we also have the quickest s/c 2015 car, and it too, has 2" headers
     
  10. PaleRider

    PaleRider Death Spank Established Member

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    Thanks Beefcake.
    For a moment I thought I was going to have an opportunity to unload Exhaust Gas Technology and Header Theory.
     
  11. noldevin

    noldevin Active Member Established Member

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    Apologies, too much time on the Facebook groups. Forgot there are a few legitimate big power builds floating around that might take advantage
     
  12. beefcake

    beefcake Authorized Vendor Authorized Vendor

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    we also ran a 4" collector and 4" exhaust!!!!!
     
  13. Weather Man

    Weather Man Persistance Is A Bitch Premium Member Established Member Top Shelf Gentlemen

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    Jelly! Thought I was boss for going to a 3.5" collector. :)
     
  14. PaleRider

    PaleRider Death Spank Established Member

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    That is awesome. Oval exhaust pipes?
     
  15. assasinator

    assasinator 1 N the head,2 N da chest Established Member

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    sorry to say it man, but your header 'theory' is wrong in every way.

    diameter, length and collector dimension determine rpm band.

    i dont know where to start.

    first, it is always possible to go with too large of a primary tube, but that overkill is determined by exhaust gas flow in pounds per minute.

    if you have two engines....a 400 inch big block making 600 crank hp is going to like the same basic primary tube as a small block making 600hp.

    where there is a difference is rpm tuning exhaust pulses for a supersonic low pressure wave to arrive at the exhaust valve as it is opening.

    a big engine needs a longer lol tube to slow the arrival of the pulse for lower rpm operation. a small high rpm engine needs shorter primary tubes for a faster arriving pulse.

    the tube diameter can change for tuning. a smaller tube shortens the primary length required for pulse arrival at the same rpm.


    it takes too long to explain everything, but simple adding tubing area has nothing to do with primary tube effectiveness.

    there is a venturi effect of primary tubing from exhaust gas inertia also. too large of a tube for the exhaust gas volume negates that advantage. THAT and rpm tuning are the reason a particular tube can be too large.

    and every change in diameter a tube makes send a pulse down the exhaust and back to the valve. THAT is why stepper headers work. they allow multiple rpm sweet spots for diameter changing pulses.

    that is about one percent of header theory.
     
    Last edited: Oct 27, 2016
  16. assasinator

    assasinator 1 N the head,2 N da chest Established Member

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    http://www.onallcylinders.com/2015/...-at-the-science-behind-exhaust-header-tuning/


    Inertial scavenging of gases begins as soon as the exhaust valve opens. Here, exhaust gases move past the valve and exit through the exhaust port into the header primary tube (and eventually working their way into the atmosphere). Hooker says the best power is produced with an exhaust gas speed of approximately 300 feet per second

    This sonic wave is moving quickly—much quicker than the ever-expanding exhaust wave we discussed above. When the sonic wave arrives at the end of the primary tube, a negative shock wave is generated, and this wave travels backward toward the exhaust port (because it is reflected).

    i have been making headers off and on for 30 years more or less. this is old tech. lost it seems on today's bunch.
     
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  17. noldevin

    noldevin Active Member Established Member

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  18. SixPak

    SixPak Member Established Member

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    Well, I monsooned my exhaust in a shopping center parking lot failing to negotiate a damned speed bump properly, and wound up re-orienting everything from the flange at the headers back to the mufflers to the right about an inch or so. Had to spin the header flange and grind it a bit, pry a few places and it still looks like crap out back, so I have decided to replace the whole works.
    I remembered this thread from a while back and dug it up to see what the latest thinking was and have decided 1-3/4" Kooks LT/mid length w/OR-H and to the back is where I am headed. I was considering the 1-5/8" but may supercharge it before all is said and done, so 1-3/4" it is. I will be curiose to see if I gain anything over and above what could be considered normal going from hi-flow cats to catless. I have always felt that I left something on the table with the BBK's and Hi-flow cats.
     
  19. fuelforfire87

    fuelforfire87 Active Member Established Member

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    Kooks are a big step up from BBK headers as as far as quality. I've had both. I had BBK 1-3/4" ceramic headers for the first 2 or 3 years I've had my car and when I took them off they had some surface rust on them. I only drive my car in nice weather too and store it during the winter. I ordered a set of ceramic coated 1-7/8" kooks headers and offroad x-pipe from maryland speed and holy cow you can see why they cost so much when you open the box and look at them. Even with 1-3/4" you should be fine for boosting. I just went with the 1-7/8" size because most people recommend that size if going turbo or supercharger. Also if you need to pass emissions kooks has their green cat mid pipes that won't throw any CELs like most high flow cats.
     
  20. 2012 Boss 302

    2012 Boss 302 Member Established Member

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    Waking this up.

    Shaun, have you looked at these any more? They also seem to go against your previous statement about 1 7/8 primary tubes.

    Not doubting your recommendations, just asking questions.....
     

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