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  1. #21
    Join Date
    Mar 2009
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    Quote Originally Posted by 67-LS1 View Post
    OK! Figured out how to attach the curve!

    I clearly don’t understand this, hence my OP and I do appreciate you guys trying to explain it. I know this formula is tried and true and has been since the invention of the horse.

    But then I see a curve like the attached and hopefully you can see why I ask the question. The HP curve rises as the torque curve remains flat.
    Thanks for posting the chart. The 5252.113 unit conversion is specific to ft-lbf and horsepower.

    For Newton-meters and kilowatts, the formula would be as follows:

    KW = Tq (Nm) * RPM / 9549.3
    Brett H.

    1979 Pontiac Firebird Trans Am
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    2005 Ford Mustang GT

    1987 Ford Mustang GT - Sold 06-29-2014
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    1992 Chevrolet Corvette - Sold 10-12-2017

  2. #22
    Join Date
    Sep 2008
    Location
    Jacksonville, Florida
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    Quote Originally Posted by 67-LS1 View Post
    OK! Figured out how to attach the curve!

    I clearly don’t understand this, hence my OP and I do appreciate you guys trying to explain it. I know this formula is tried and true and has been since the invention of the horse.

    But then I see a curve like the attached and hopefully you can see why I ask the question. The HP curve rises as the torque curve remains flat.
    Lets just pick an RPM from the graph, say 1800 RPM. It's making roughly 350 Nm of torque, convert that to Lb. ft. and you get roughly 258 Lb. Ft.

    258 x 1800/5252 = 88 hp. At the same 1800 RPM on the graph, it shows 65 KW's of power, convert that to HP and guess what, 88 HP.

    Try it at any RPM point on the graph and you will get the same results. The formula with always be correct!!
    Craig Scholl
    CJD Automotive, LLC
    Jacksonville, Florida
    904-400-1802
    www.cjdautomotive.com

    "I own a Mopar, I already know it won't be in stock, won't ship tomorrow, and won't fit without modification."

  3. #23
    Join Date
    Jun 2001
    Location
    Orlando, FL
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    Right -- just piling on here, but the relationship between HP, torque, and RPM isn't "tried and true". It's true by definition:

    1 horsepower is a unit of power equal to 550 foot-pounds per second (745.7 watts).
    John Parsons



    II Much Fabrication's Blog -- New products, Fabrication sequences, etc.

    II Much Fabrication's Current Build -- LS9-powered 69 Camaro

  4. #24
    Join Date
    Jun 2012
    Location
    South Lyon, MI
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    Quote Originally Posted by parsonsj View Post
    Right -- just piling on here, but the relationship between HP, torque, and RPM isn't "tried and true". It's true by definition:

    1 horsepower is a unit of power equal to 550 foot-pounds per second (745.7 watts).
    What he said!

  5. #25
    Join Date
    Jun 2001
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    Los Angeles
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    Getting the units right in any engineering exercise may just save a life.

    Just sayin....
    VaporWorx. We Give You Gas http://www.vaporworx.com

  6. #26
    Join Date
    Jun 2012
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    South Lyon, MI
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    Quote Originally Posted by CarlC View Post
    Getting the units right in any engineering exercise may just save a life.

    Just sayin....
    I always wonder why by doctor and lawyer friends just "practice", when as an engineer I have to get it right every time.

  7. #27
    Join Date
    Nov 2016
    Location
    Sulphur, La
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    407
    Quote Originally Posted by cornfedbill View Post
    I always wonder why by doctor and lawyer friends just "practice", when as an engineer I have to get it right every time.
    Right every time... that's what the safety multiplier is for!

  8. #28
    Join Date
    Jun 2012
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    South Lyon, MI
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    Quote Originally Posted by CSG View Post
    Right every time... that's what the safety multiplier is for!
    Yup!

  9. #29
    Join Date
    Sep 2006
    Location
    Southern Indiana
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    4,663
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    All engines power is measured by torque, we get HP by an equation. Physics isn't hard if you understand what hat there are some constants in the world.

    Lee Abel
    AFTERMARKET PERFORMANCE

    1977 Chevy Monza 2+2:Project "Cheap Trick"
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