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  1. #1
    Old Ski Insanity w/rpm500's Avatar
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    10=10 rule.. What about ports?

    Most of us know the 10=10 rule ..for .010 head mill, there is an average increase of 10 psi..

    Is there a rule for port height?

    logically, as you go up in port height ,meaning closer to the top, you loose psi...( less time to compress)

    does some sort of RULE apply here too?,that for every .010 up (say an average cut arc across the port opening) is there an approx 1 1/2 lb. psi loss??

    I'm loosly thinking ( #'s stated are from my diameter cylinder and port size..) an exhaust port with a width of 50 degrees radius , for every .070 up (roughly), its a 10 psi drop??

    then a cylinder with more degree percentage of port (size) will change value of height cut...a port of 60 degrees may need a .060 cut to have a 10 psi drop..(once again, #'s bounced against my findings) .

    friggin math..

    May be WATERWOODY will chime in with his porting knowlage and verify this or correct it.... I'm not asking for secrets just general info ,to verify something.. thanks guys


  2. #2
    WATER WOODY's Avatar
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    check pm

  3. #3
    Old Ski Insanity w/rpm500's Avatar
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    Quote Originally Posted by WATER WOODY View Post
    check pm
    got ya!! will do, later this evening ! thanks

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