Conversion factor between rwhp and crank?
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From: Huntsville AL
Conversion factor between rwhp and crank?
The car is a 2010 Grand Sport convertible, automatic transmission, and supercharged. I'm told it has 630 hp at the crank. How much would this convert into at the wheels? I do not have the dyno sheet and I assume they converted it.
I've heard some general conversion factors, but I'm wondering if anyone has actual numbers on a similar car. It seems like the manual car is pretty efficient but I do not know about the automatic.
I've heard some general conversion factors, but I'm wondering if anyone has actual numbers on a similar car. It seems like the manual car is pretty efficient but I do not know about the automatic.
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From: Apache Junction AZ
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Every Dyno is different. The most common Dynos lose 60HP flywheel to rear wheels for a standard trans and 70HP flywheel to rear wheels for an automatic.
I.E.;
An LS2 would be 400HP flywheel down to 340HP stick and 400 down to 330HP Auto.
An LS3 would be 430HP flywheel down to 370HP stick and 360HP auto.
I.E.;
An LS2 would be 400HP flywheel down to 340HP stick and 400 down to 330HP Auto.
An LS3 would be 430HP flywheel down to 370HP stick and 360HP auto.
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From: Fort Worth, Texas
It's a fixed/percentage imo and hard to put an exact number on it, but make sure you are comparing the same correction factors as many chassis dyno numbers are SAE and engine dyno numbers are STD.
Melting Slicks
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From: On the east coast we drive until we die
I've always leaned towards this theory myself. If a 400 hp LS2 loses 60hp through the drivetrain, which is 15%. Why wouldn't a 500hp LS2 lose 60hp through the same drivetrain and not 75hp(15%)? Why does the percentage stay the same with the power increase?
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Thread Starter
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From: Huntsville AL
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All other things equal its a fixed HP loss, NOT a percentage.
The A6 takes 10 HP to run, whether it's 10HP from a 400HP LS2 or a 436HP LS3. Same with the rear gears, a fixed amount of HP, NOT a percentage.
The A6 takes 10 HP to run, whether it's 10HP from a 400HP LS2 or a 436HP LS3. Same with the rear gears, a fixed amount of HP, NOT a percentage.
Melting Slicks
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There will be parasitic drag as the engine tries to turn itself and the transmission over faster.
Just like how doubling horsepower doesn't mean top speed is doubled. That is an extreme example, but the transmission and gearing is spinning through fluids. The faster you want to spin it, the more effort and power it will use.
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Melting Slicks
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Has to be a percentage, example, if a 400 crank horsepower motor looses 60 horse thru the driveline, a 100 horsepower car looses 15 horsepower not 60, cannot be fixed
Melting Slicks
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From: On the east coast we drive until we die
Personally I believe it starts off at, lets say 15% (60hp), and then the percentage starts to drop slightly as the power increases but not at the same ratio to sustain the original 60hp loss.
Rudimentary example:
400hp LS2 loses 60hp (15%)
500hp LS2 loses 70hp (14%)
600hp LS2 loses 78hp (13%)
These are just examples of my theory based on almost nothing. Kinda thinking out loud.
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I think he means it's fixed for a certain engine and drivetrain combo. Could you even make a 400 hp LS2 only make 100 hp?
Personally I believe it starts off at, lets say 15% (60hp), and then the percentage starts to drop slightly as the power increases but not at the same ratio to sustain the original 60hp loss.
Rudimentary example:
400hp LS2 loses 60hp (15%)
500hp LS2 loses 70hp (14%)
600hp LS2 loses 78hp (13%)
These are just examples of my theory based on almost nothing. Kinda thinking out loud.
Personally I believe it starts off at, lets say 15% (60hp), and then the percentage starts to drop slightly as the power increases but not at the same ratio to sustain the original 60hp loss.
Rudimentary example:
400hp LS2 loses 60hp (15%)
500hp LS2 loses 70hp (14%)
600hp LS2 loses 78hp (13%)
These are just examples of my theory based on almost nothing. Kinda thinking out loud.
Tech Contributor
Joined: Oct 1999
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From: Charlotte, NC (formerly Endicott, NY)
I think he means it's fixed for a certain engine and drivetrain combo. Could you even make a 400 hp LS2 only make 100 hp?
Personally I believe it starts off at, lets say 15% (60hp), and then the percentage starts to drop slightly as the power increases but not at the same ratio to sustain the original 60hp loss.
Rudimentary example:
400hp LS2 loses 60hp (15%)
500hp LS2 loses 70hp (14%)
600hp LS2 loses 78hp (13%)
These are just examples of my theory based on almost nothing. Kinda thinking out loud.
Personally I believe it starts off at, lets say 15% (60hp), and then the percentage starts to drop slightly as the power increases but not at the same ratio to sustain the original 60hp loss.
Rudimentary example:
400hp LS2 loses 60hp (15%)
500hp LS2 loses 70hp (14%)
600hp LS2 loses 78hp (13%)
These are just examples of my theory based on almost nothing. Kinda thinking out loud.
Bill
Melting Slicks
Joined: Jan 2013
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From: Dallas Tejas
Every Dyno is different. The most common Dynos lose 60HP flywheel to rear wheels for a standard trans and 70HP flywheel to rear wheels for an automatic.
I.E.;
An LS2 would be 400HP flywheel down to 340HP stick and 400 down to 330HP Auto.
An LS3 would be 430HP flywheel down to 370HP stick and 360HP auto.
I.E.;
An LS2 would be 400HP flywheel down to 340HP stick and 400 down to 330HP Auto.
An LS3 would be 430HP flywheel down to 370HP stick and 360HP auto.
Race Director
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From: Austin Texas
Remember that a supercharged engine is developing much more HP than what is measured at the flywheel. That belt driven blower takes HP to turn.
Read somewhere that a 426 Hemi Supercharger needed 70HP to develop 8 pounds of boost.
Read somewhere that a 426 Hemi Supercharger needed 70HP to develop 8 pounds of boost.