calculating flywheel from rearwheel HP
04-09-2006, 03:37 PM
#1
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Posts: 117
calculating flywheel from rearwheel HP
RWHP Flywheel
276.6 359.6 76.9240% +1z
251.8 327.3 76.9217% -1z
12.42253022 16.15195737 1.13133E-05 Dyno RWHP Flywheel
264.2 343.5 76.922822% 279 362.7
257.98 335.37 76.9240% 278.192 361.7
260.32 338.42 76.9222%
274.16 356.41 76.9226% 272.3861 354.1
279.07 362.79 76.9233% 267.5 347.8
277.87 361.24 76.9212% 267 347.1
262.91 341.79 76.9215%
259.31 337.1 76.9238%
241.98 314.57 76.9241%
Rear Wheel HP (RWHP) / 76.922822 % = flywheel HP
i got it from http://www.onlineconversion.com/horsepower.htm caculations done w Gtech pro competition provided 1/4 mi times ( NOT Gtech pro competition HP calcs.).
column 1 = RWHP from Online Conversions site; column 2 = flywheel HP from Online Conversions site; col. 3 = % calculated from former; column 4 = dyno measured HP; col. 5 = calc flywheel HP
My question is does the 76.922822 % seem reasonable?
04-09-2006, 05:40 PM
#2
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Join Date: Apr 2005
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Posts: 475
RE: calculating flywheel from rearwheel HP
That thing is way off for flywheel #'s
Manual: BHP = RWHP X 1+(Altitude X .00003) X 1.15
Automatic: BHP = RWHP X 1+(Altitude X .00003) X 1.22
So no, that does not seem reasonable, too many variables, that calculator is crap.
04-09-2006, 06:11 PM
#5
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Join Date: Apr 2005
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RE: calculating flywheel from rearwheel HP
ORIGINAL: V8 Aggie
Hey GTRacing... were you out at TWS the other weekend? If so I am the college guy that came up to you and said I had the 05 mineral grey. You looking to come back?
btw- what was your best time? mine was a 2.16, but that was with an instructor driving it. She said the car had more but she didn't want to push a car that she didn't know the limits of.
Hey GTRacing... were you out at TWS the other weekend? If so I am the college guy that came up to you and said I had the 05 mineral grey. You looking to come back?
btw- what was your best time? mine was a 2.16, but that was with an instructor driving it. She said the car had more but she didn't want to push a car that she didn't know the limits of.
04-18-2006, 10:02 PM
#6
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Join Date: Mar 2006
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Posts: 117
RE: calculating flywheel from rearwheel HP
ok, Tic_Tok and GTRacing are more right.
I called Chris at Dynojet and explained the situation. I asked if there was a mathematical formula they used to calculate BHP (Flywheel) from measured RWHP on Dynojet. He said emphatically NO. He went on to say there are just too many variables (e.g., torque of drive shaft, etc. etc.) to realistically measure. He said I could pull the engine and put it on an engine dyno and get pretty close.
we went on to discuss and he suggested a very rough rule of thumb would be a very efficient engine/drive train would lose 12% a less efficient Mustang would lose 20%. He believes that the 2005+ automatic transmission probably is in the 15%-17% range of loss of HP BHP to RWHP.
therefore:
%------- BHP------ RWHP
88%---- 316.6---- 278.6
85%---- 327.8---- 278.6
83%---- 335.7---- 278.6
80%---- 348.3---- 278.6
I called Chris at Dynojet and explained the situation. I asked if there was a mathematical formula they used to calculate BHP (Flywheel) from measured RWHP on Dynojet. He said emphatically NO. He went on to say there are just too many variables (e.g., torque of drive shaft, etc. etc.) to realistically measure. He said I could pull the engine and put it on an engine dyno and get pretty close.
we went on to discuss and he suggested a very rough rule of thumb would be a very efficient engine/drive train would lose 12% a less efficient Mustang would lose 20%. He believes that the 2005+ automatic transmission probably is in the 15%-17% range of loss of HP BHP to RWHP.
therefore:
%------- BHP------ RWHP
88%---- 316.6---- 278.6
85%---- 327.8---- 278.6
83%---- 335.7---- 278.6
80%---- 348.3---- 278.6
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