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  1. #1
    Join Date
    Jun 2015
    Location
    Perth WA
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    118

    Rear wheel to flywheel conversion.

    How do you figure out flywheel conversions. I have 649 rwhp and 825 nm at the tread. What would flywheel be? Roughly obviously.
    VF GTS, 22.5% overdrive pulley, 2" primary 4-1 extractors on to twin 3" exhaust, Cold Air, 160 deg thermostat, Cam, double valve springs, 65lbs injectors. 649 rwhp.

  2. #2
    Join Date
    Jan 2004
    Location
    Perth, WA
    Posts
    6,920
    I've always said rwhp is close to flywheel kW. If you run up a car in standard form, it's generally pretty close

  3. #3
    Join Date
    Feb 2016
    Posts
    519
    Quote Originally Posted by white_lie View Post
    I've always said rwhp is close to flywheel kW. If you run up a car in standard form, it's generally pretty close

    I am not sure I get that.
    Are you are saying he has 649fwkw?
    or
    870fwhp?
    Smitty
    Member PIARC VICV8s Old Fart Racing
    GEN-F R8 340 Clubsport Tourer VK race car Kwaka ZX12R

  4. #4
    Join Date
    Feb 2014
    Posts
    4,595
    It's going to vary dyno to dyno.
    With dyno numbers you always want to be on the same dyno strapped into both rollers for consistency.
    Use the dyno purely for tuning.

    If you drag race the car the track will tell you your engine HP with your MPH versus weight.
    There are plenty of cars that claim big HP numbers but can't back them up at the track and mph never lies.

    I'd rather use a low reading dyno that's consistent than some of the Disney dynos out there.

    2014 HSV GenF-GTS fitted with a Forced Induction Interchiller
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  5. #5
    Join Date
    Jan 2004
    Location
    Perth, WA
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    6,920
    Quote Originally Posted by Smitty View Post
    I am not sure I get that.
    Are you are saying he has 649fwkw?
    or
    870fwhp?
    Yup.
    Some will say the drivetrain loss isn't a constant percentage (34% when converting HP to kW) but if you take a 100kw 4 cylinder and it makes 100rwhp then compare it to a 400kw V8 that makes 400rwhp, they're generally pretty similar, give or take for dynos, freak engines, some engines being constantly under rated, etc etc

  6. #6
    Join Date
    Jun 2015
    Location
    Perth WA
    Posts
    118
    Cheers for the replies but was only looking for a rough estimation, all dynos vary. My driving on the strip might no pay homage to the car.

    Kind of want to know the torque figure
    VF GTS, 22.5% overdrive pulley, 2" primary 4-1 extractors on to twin 3" exhaust, Cold Air, 160 deg thermostat, Cam, double valve springs, 65lbs injectors. 649 rwhp.

  7. #7
    Join Date
    Apr 2016
    Location
    Liverpool Sydney
    Posts
    472
    Quote Originally Posted by Remdogg View Post
    How do you figure out flywheel conversions. I have 649 rwhp and 825 nm at the tread. What would flywheel be? Roughly obviously.
    Roughly speaking - 649rwhp = 791hp at the flywheel ( 791fwhp ).

    LS2 V3 Vortech Supercharged
    607rwhp

  8. #8
    Join Date
    Jun 2015
    Posts
    180
    Another way to look at it is this,

    Modified rwhp figure minus 100% stock rwhp figure added to the manufactures claimed standard flywheel figure to find new flywheel HP.

  9. #9
    Join Date
    Jun 2015
    Location
    Perth WA
    Posts
    118
    Quote Originally Posted by GenF-GTS View Post
    It's going to vary dyno to dyno.
    With dyno numbers you always want to be on the same dyno strapped into both rollers for consistency.
    Use the dyno purely for tuning.

    If you drag race the car the track will tell you your engine HP with your MPH versus weight.
    There are plenty of cars that claim big HP numbers but can't back them up at the track and mph never lies.

    I'd rather use a low reading dyno that's consistent than some of the Disney dynos out there.

    So if I take it down the 1/4 what's your formula to work out jp from my 1/4 mile time.
    VF GTS, 22.5% overdrive pulley, 2" primary 4-1 extractors on to twin 3" exhaust, Cold Air, 160 deg thermostat, Cam, double valve springs, 65lbs injectors. 649 rwhp.

  10. #10
    Join Date
    Jan 2004
    Location
    Perth, WA
    Posts
    6,920
    Quote Originally Posted by Remdogg View Post
    So if I take it down the 1/4 what's your formula to work out jp from my 1/4 mile time.
    This has been the tried and true method used for years and years and comes in pretty close

    http://m.ebay.com.au/itm/MOROSO-POWE...-/131453967576

    There are plenty of online calculators you plug ET, MPH and weight in to and they'll tell you what hp is required to run that.







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