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Split 6 Exhaust - Why ?

Discussion in 'The Hokey Ass Message Board' started by TheMonkey, Jan 28, 2010.

  1. TheMonkey
    Joined: May 11, 2008
    Posts: 310

    TheMonkey
    Member
    from MN

    I searched here and elsewhere... found loads of examples, but haven't really found the 'why'?

    Just for the sound? Or is there some sort of performance theory?
     
  2. James Curl
    Joined: Mar 28, 2006
    Posts: 370

    James Curl
    Member

    I split the manifold on my flathead Plymouth I/6 and added dual exhaust. It seems to increase the power band and the little engines need all the help they can get. I also have dual carbs and a mild cam and milled the head .100 which also helps.
     
  3. 39 All Ford
    Joined: Sep 15, 2008
    Posts: 1,531

    39 All Ford
    Member
    from Benton AR

    IMO the sound alone is enough of a reason.
     
  4. Porter Man
    Joined: Oct 14, 2007
    Posts: 377

    Porter Man
    Alliance Vendor
    from Mound, MN

    Because they sound cool as hell!!!!!!!!!
    Nothing even sounds close to it, it's one of a kind.
     
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  5. jcmarz
    Joined: Jan 10, 2010
    Posts: 4,636

    jcmarz
    Member
    from Chino, Ca

    Mainly for that rapping sound but it also helps the engine breath better so you get a little more pep.
     
  6. belair
    Joined: Jul 10, 2006
    Posts: 8,189

    belair
    Member

    You've obiously never heard one go by.
     
  7. Have you ever heard the sound of a split manifold on an old six? A sweeter noise you will never experience. :)
     
  8. thewishartkid
    Joined: Jun 23, 2006
    Posts: 873

    thewishartkid
    Member

    If you have to ask!!!
     
  9. MERC 55
    Joined: Mar 26, 2007
    Posts: 277

    MERC 55
    Member

    He's from MN they never get to open their windows
     
  10. TheMonkey
    Joined: May 11, 2008
    Posts: 310

    TheMonkey
    Member
    from MN

    i've heard it... just wondering if it was the sound alone is why people do it.
     
  11. HealeyRick
    Joined: May 5, 2009
    Posts: 553

    HealeyRick
    Member
    from Mass.

    To better control exhaust manifold pulses. My Dad's 1967 Pontiac LeMans Sprint with the OHC-6 4 bbl had splits, sure sounded good:

    [​IMG]
     
  12. 52HardTop
    Joined: Jun 21, 2007
    Posts: 837

    52HardTop
    Member

    Well, why not? If it's good enough for the first Vettes it's should be good enough for Dads old sedan! Besides, like it's been said, they sound cool.
    Dom
     
  13. waldo53
    Joined: Jan 26, 2010
    Posts: 836

    waldo53
    Member
    from ID

    That's the same question my dad asked me when I was in HS and I wanted to put duals on my '49 Fleetline. I told him it made the engine run cooler, last longer, and get better mileage. He then loaned me the $30 to get a split manifold from Sears and Roebuck (yes, they used to carry lots of hot rod stuff)

    Real reason = you can't beat the sound of an inliner with duals. That was 50 years ago, I still run Fentons and 22" Smittys on my 235. Still love that sound!!!
     
  14. TheMonkey
    Joined: May 11, 2008
    Posts: 310

    TheMonkey
    Member
    from MN

    so - everyone has a traditional 3-3 split front to back? i understand the performance gain from that.

    BUT - i have always thought that the 'rappy' split exhaust was a 2-4 split, which i'm not ever sure what it is (other than 2 out one, 4 out the other) - which seems like it would have some sort of bizarre pulse stream.

    so what split is it that makes the sweet sound? if it's the 3-3 split, then what is a 2-4 split? oh - and why? :)
     
  15. Fingers
    Joined: Feb 23, 2005
    Posts: 105

    Fingers
    Member

    Both, can't beat the sound AND pick up a bit of power as well = win-win
     
  16. 52HardTop
    Joined: Jun 21, 2007
    Posts: 837

    52HardTop
    Member

    I think what your talking about is the way the cylinders are split into the exhaust manifold? The 2 4 split would be the fact that the first cylinder is exhausting out on it's own and the second and third cylinders are sharing the second pipe of the manifold. Three and four share a pipe with the last cylinder on it's own. Right? The six exhaust valves are split up amongst four outlets in the head.
    Dom
     
  17. Rickybop
    Joined: May 23, 2008
    Posts: 5,930

    Rickybop
    Member
    from Michigan

    There is no "2-4" split. A stock exhaust manifold has a common plenum. When it's "split", there's simply another opening for the exhaust to exit. The only time the exhaust is actually split, is when an after-market set of dual manifolds is installed. I honestly can't say that I've heard a six with a modified stock manifold, and knew it. I have heard dual manifolds, and I'll tell you, they rap. Maybe you can find a running car on youtube with the modified stock manifold, and compare it to a video of a car with dual manifolds.
     
  18. Jims35
    Joined: Dec 22, 2009
    Posts: 279

    Jims35
    Member

    I allways used the 2-4 split, I never had to do anything to the heat source under the carb. by staying away from it . The why is , because I can . I liked the sound to.
     
  19. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,592

    HEATHEN
    Member
    from SIDNEY, NY

    Wrong. A stock straight six exhaust manifold has a common plenum IN STOCK FORM. A very important part of splitting it is to, once the second outlet has been added, internally divide the manifold into two separate chambers so that three cylinders dump into the stock outlet and the other three dump into the new outlet. Simply adding a second outlet doesn't make any additional sound at all. A friend added a second outlet to his '54 Chevy truck without dividing the manifold and, even with dual glasspacks, it was still whisper quiet. I cut open the back of the manifold and inserted a steel divider plate-----BIG difference in decibel level!

    The "2-4" split was usually done on manifolds that were difficult or impossible to split evenly; the Ford 223 comes to mind, since its center two exhaust ports both dumped into the stock outlet below the heat riser.
     
  20. Rickybop
    Joined: May 23, 2008
    Posts: 5,930

    Rickybop
    Member
    from Michigan

    I stand corrected, HEATHEN. I wasn't aware that a separator plate was traditionally involved. So without the plate, it is a common plenum, but with the plate, it's a 3-3 split...correct? So there is, in fact, no 4-2 split on the Chey. I like this place. 100,000 heads is better than one.
     
  21. lippy
    Joined: Sep 27, 2006
    Posts: 4,217

    lippy
    Member
    from Ks

    Bingo. Just do it! :D
     
  22. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,592

    HEATHEN
    Member
    from SIDNEY, NY

    Right. Because of the 216/235/261's 1-2-2-1 exhaust port arrangement, it's ideal for an even 3-3 split.
     
  23. fullhouse296
    Joined: Jan 30, 2009
    Posts: 378

    fullhouse296
    Member
    from Australia

    153624 usual firing order .on our old stockcar we made a header flange ,153 ran to a cone and back via 3 feet of 2inch pipi 624 did likewise . sure sounded cool but pulled a tad harder out of the bends when the two 2inch collectors were joined at about half their length and had half what was left welded on . didnt sound as evil but we left it as this .Blueflame six ,destroked to 221 ,600 4bbl dirt track in New Zealand .
     
  24. von Dyck
    Joined: Apr 12, 2007
    Posts: 678

    von Dyck
    Member

    I ran cylinders 1-2-3 into one collector, and 4-5-6 into another collector. What you end up with is equally spaced exhaust pulses in each individual collector 240* apart that are easily tuneable by the length of the collector. The open headers at RPM have the sound of a radial airplane engine. The reason V-8 collectors sound rough have to do with the uneven firing pulses emitted from each collector.
     
  25. blueskies
    Joined: Jan 22, 2003
    Posts: 546

    blueskies
    Member
    from Idaho

    I split my flathead six with tube headers and a crossover just ahead of a pair of smithys. No rapping or rackackack cackling, just smooth music to my ears...


     
  26. greasemonkey060
    Joined: Dec 18, 2005
    Posts: 212

    greasemonkey060
    Member

    You gotta hear it, to "get it".
     
  27. LB+1
    Joined: Sep 28, 2006
    Posts: 569

    LB+1
    Member
    from 71292

    piper cub down the run way right before take off
     
  28. Jims35
    Joined: Dec 22, 2009
    Posts: 279

    Jims35
    Member

    When I had them split we cut the manifold in to two seperate parts . Capping each one off , then making a outlet for the short one that came off of two cylinders. We were not concerned about a good flow of exhaust , just lots of noise . This was back in the 1950s
     
  29. Dynaflash_8
    Joined: Sep 24, 2008
    Posts: 3,012

    Dynaflash_8
    Member
    from Auburn WA

    <object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/smyHCN2DNC8&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/smyHCN2DNC8&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>


    This is why
     
  30. TheMonkey
    Joined: May 11, 2008
    Posts: 310

    TheMonkey
    Member
    from MN

    but, on a chevy 216 or 235, the exhaust ports are set up as 1 - 2 - 2 - 1... not sure that could be cut the way you are describing it.

    it must have been something set up like 1 - 1- 2 - 1 - 1? ford?
     

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