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Thread: hp for mph

  1. #1
    Join Date
    Jul 2002

    hp for mph

    Is there a rule of thumb for how much mph you get when you add x amount of hp? Assume twin engine , 35' deep v boat and current top of 80 mph, if I add 100 total hp (50 per engine) what would mph be, what about 200 total hp?

  2. #2
    Registered rjcardinal's Avatar
    My Boats:
    '99 27 Fountain Fever
    Join Date
    Jan 2001
    Baton Rouge, LA
    On a single engine V it takes between 12 and 20 hp to gain 1 mph. This is assuming you are not near the limits of the hull.


  3. #3
    Registered Rambunctious's Avatar
    My Boats:
    95 Formula 336 SR1 525SC's
    Join Date
    Jul 2001
    Holland, Mich
    the typical, approximate behavior of a v bottom follows a squared law

    we need to know your current horsepower at the 80 mph

    but, if i take a guess and say 2x500= 1000
    then adding 100 hp total might give you:

    80^2 / 1000 = x^2/1100

    x = new speed = 83.9

    for 200 hp increase:

    80^2/1000 = x^2/1200

    x = 87.6

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