Does My Rwhp and Crank Horse power make sense??
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This is a discussion on Does My Rwhp and Crank Horse power make sense?? within the Comparison: WRX vs World forums, part of the Community - Meet other Enthusiasts category; sorry I know this is the racing forum but This is the forum were Ifind the people are most knowledgable.. ...

  1. #1
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    Does My Rwhp and Crank Horse power make sense??

    sorry I know this is the racing forum but This is the forum were Ifind the people are most knowledgable.. LOL. seriously..

    ok here try to stick with me here
    Most STI's dyno stock between 225-230 at wheels right. that equals 300 HP at the crank (25% drivetrains loss) so this is the math. 300 Multiply(x) 0.25 equals 75 and u add 75 to 225-230 u get 300 HP make sense? Or u take 230 devide that by 0.75 u get exactly 306 which is crank HP


    Now my STI dynod exactly 230 2 times when it was stock.
    After My Dowpipe , full exhaust , ecutek and boost set to 19.5 psi

    I dynod at 273 at wheels..NOW U take 273 devide that by 0.75 which equals 364 which is my crank HP. or I take 364 Multiply(x) that by 0.25 which equals 91 ADD 91 to 273 and that equals 364!!
    which is my final HP # at the Crank!!
    Not bad huh... lol I hope u can follow this and correct me if I'm wrong.. but i did include the 25% drivetrain loss

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    Registered User hellafastWRX's Avatar
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    lol i see what you're saying, but what's the point you're trying to make!?

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    that I have a **** load of HP

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    Registered User 1fastsubie's Avatar
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    You can't always go by a flat % loss. If you were making 1000hp at the wheels would your flywheel hp be 1250? I wouldn't think so. See what I mean?

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    Registered User 2004NeonSRT4's Avatar
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    Re: Does My Rwhp and Crank Horse power make sense??

    Originally posted by Tailspin
    sorry I know this is the racing forum but This is the forum were Ifind the people are most knowledgable.. LOL. seriously..

    ok here try to stick with me here
    Most STI's dyno stock between 225-230 at wheels right. that equals 300 HP at the crank (25% drivetrains loss) so this is the math. 300 Multiply(x) 0.25 equals 75 and u add 75 to 225-230 u get 300 HP make sense? Or u take 230 devide that by 0.75 u get exactly 306 which is crank HP


    Now my STI dynod exactly 230 2 times when it was stock.
    After My Dowpipe , full exhaust , ecutek and boost set to 19.5 psi

    I dynod at 273 at wheels..NOW U take 273 devide that by 0.75 which equals 364 which is my crank HP. or I take 364 Multiply(x) that by 0.25 which equals 91 ADD 91 to 273 and that equals 364!!
    which is my final HP # at the Crank!!
    Not bad huh... lol I hope u can follow this and correct me if I'm wrong.. but i did include the 25% drivetrain loss



    that was a big waste of time doing all that work. who cares what it is a the crank it's whats gets to the wheels the mater.
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    Registered User silverscooby's Avatar
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    Originally posted by Tailspin
    that I have a **** load of HP
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    Registered User OffRoadWagon's Avatar
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    The engine's output counts more on a technical/engineering standpoint. They get into sophistication factors and crap like that, based on how much hp/liter an engine is making. You could hook up a 800 crank hp 2.0L four cylinder engine to a drivetrain made of cast iron, and end up with like 15whp, but you still have one hell of a high performance engine on your hands.

    And driveline % loss seems to be the way to go. By using a %, it does increase proportionally with the amount of power you're making, so really it isn't a "flat" loss at all, it is a moving number. 1250 crank hp with a 25% loss is 937.5hp, actually, so I think you meant 1333hp with a 25% loss would be 1000hp at the wheels. If it really would be or not, I don't know. I'm not an auto engineer, and I don't know if things would start getting weird at those power levels. But from the basic rules that I've picked up, it should be that way.

    Check out this thread, it has a link in it that should help clear things up.
    -ORW


    Quote Originally Posted by Integra96
    I'll get under there this weekend and see if I can loosen things up and maybe shoot some lube juice up in there.

    Oh sht, please don't sig that.

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    Shouldn't the drivetrain loss max out at some point or another? There has to be a point where you really don't need to factor in the drivetrain loss any longer. Let's say that you're making 4,000 horsepower, are you telling me that you'd lose 1,000 horsepower due to powertrain loss? Just a thought

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    Registered User DenverWRX's Avatar
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    RWHP? Rear Wheel Horsepower? What the hell is all that power doing just back there?
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    Registered User silverscooby's Avatar
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    There's always been a debate on where the percentage of drivetrain loss becomes static. Surely at 1000hp you can't be losing 250hp through the drivetrain. With that sort of energy it would surely melt the drivetrain parts.

    25% loss is a huge amount. That would mean my 350whp WRX was making 437hp. I dont think so.....
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    Re: Does My Rwhp and Crank Horse power make sense??

    Originally posted by Tailspin
    sorry I know this is the racing forum but This is the forum were Ifind the people are most knowledgable.. LOL. seriously..

    ok here try to stick with me here
    Most STI's dyno stock between 225-230 at wheels right. that equals 300 HP at the crank (25% drivetrains loss) so this is the math. 300 Multiply(x) 0.25 equals 75 and u add 75 to 225-230 u get 300 HP make sense? Or u take 230 devide that by 0.75 u get exactly 306 which is crank HP


    Now my STI dynod exactly 230 2 times when it was stock.
    After My Dowpipe , full exhaust , ecutek and boost set to 19.5 psi

    I dynod at 273 at wheels..NOW U take 273 devide that by 0.75 which equals 364 which is my crank HP. or I take 364 Multiply(x) that by 0.25 which equals 91 ADD 91 to 273 and that equals 364!!
    which is my final HP # at the Crank!!
    Not bad huh... lol I hope u can follow this and correct me if I'm wrong.. but i did include the 25% drivetrain loss

    dude this is the 2nd time.well 3rd someone else already said it on this thread STOP SAYING RWHP...u have a fawkn AWD car..its AWHP...got it?? ..u dont drive a vette or supra, viper etc etc..u drive a subaru wrx sti AWHP! ..damn it...sorry had 2 rant
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    Originally posted by Tailspin
    that I have a **** load of HP
    what are you a comedian?

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    Registered User 2004NeonSRT4's Avatar
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    Originally posted by SLOW4EAT
    what are you a comedian?

    i was going to mention something of that sort. but i'm an outsider and didn't wanna start anything. glad someone else did it.
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    Registered User OffRoadWagon's Avatar
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    Originally posted by silverscooby
    There's always been a debate on where the percentage of drivetrain loss becomes static. Surely at 1000hp you can't be losing 250hp through the drivetrain. With that sort of energy it would surely melt the drivetrain parts.

    25% loss is a huge amount. That would mean my 350whp WRX was making 437hp. I dont think so.....

    I'm guessing if you put a 1000hp ej20 into an otherwise stock wrx, it would indeed wreak havoc on the drivetrain components. My best guess is that it won't continue to be a 25% drivetrain loss, cause the entire drivetrain is going to be differenct. I'm sure you'd replace it all with light weight, high strength stuff, all carbon fiber and titanium and stuff.
    -ORW


    Quote Originally Posted by Integra96
    I'll get under there this weekend and see if I can loosen things up and maybe shoot some lube juice up in there.

    Oh sht, please don't sig that.

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