Can anyone explain?
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Tourer
Joined: Mar 2007
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Can anyone explain?
Have seen several posters showing dyno results of 80HP plus on their dyno sheets. All with stock motors. What is the difference between SAE & STD numbers? My bike was dynoed showing the SAE numbers and isnt anywhere near 80HP. Have 96' motor, SERT and hi flow with python staggereds. Bike runs great . Can anyone explain. My dealer says low to mid 70's in the HP range is pretty normal. 07 SB. Not trying to ruffle any feathers, just would like to know which method is correct. Thanks.
Road Captain
Joined: Apr 2007
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From: Chesapeake VA
RE: Can anyone explain?
correction factors:
SAE represents more realistic standard conditions, STD artificially boosts numbers. I do not trust a vendor who uses STD numbers. Found this somewhere on the Web:
"SAE (Society of Automotive Engineers), USA. Power is corrected to reference conditions of 29.23 InHg (99 kPa) of dry air and 77 F (25°C). This SAE standard requires a correction for friction torque. Friction torque can be determined by measurements on special motoring dynamometers (which is only practical in research environments) or can be estimated. When estimates must be used, the SAE standard uses a default Mechanical Efficiency (ME) value of 85%. This is approximately correct at peak torque but not at other engine operating speeds. Some dynamometer systems use the SAE correction factor for atmospheric conditions but do not take mechanical efficiency into consideration at all (i.e. they assume a ME of 100%).
STD or STP. Another power correction standard determined by the SAE. This standard has been stable for a long time and is widely used in the performance industry. Power is corrected to reference conditions of 29.92 InHg (103.3 kPa) of dry air and 60 F (15.5°C). Because the reference conditions include higher pressure and cooler air than the SAE standard, these corrected power numbers will always be about 4 % higher than the SAE power numbers. Friction torque is handled in the same way as in the SAE standard." Found this on-line hope it helps...I go by throttle response and seat of my pants method myself numbers are just numbers
Club Member
Joined: May 2006
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From: the 50s & the 60s
RE: Can anyone explain?
ORIGINAL: dailydriver[align=center]correction factors:[/align]SAE represents more realistic standard conditions, STD artificially boosts numbers. I do not trust a vendor who uses STD numbers. Found this somewhere on the Web:
"SAE (Society of Automotive Engineers), USA. Power is corrected to reference conditions of 29.23 InHg (99 kPa) of dry air and 77 F (25°C). This SAE standard requires a correction for friction torque. Friction torque can be determined by measurements on special motoring dynamometers (which is only practical in research environments) or can be estimated. When estimates must be used, the SAE standard uses a default Mechanical Efficiency (ME) value of 85%. This is approximately correct at peak torque but not at other engine operating speeds. Some dynamometer systems use the SAE correction factor for atmospheric conditions but do not take mechanical efficiency into consideration at all (i.e. they assume a ME of 100%).
STD or STP. Another power correction standard determined by the SAE. This standard has been stable for a long time and is widely used in the performance industry. Power is corrected to reference conditions of 29.92 InHg (103.3 kPa) of dry air and 60 F (15.5°C). Because the reference conditions include higher pressure and cooler air than the SAE standard, these corrected power numbers will always be about 4 % higher than the SAE power numbers. Friction torque is handled in the same way as in the SAE standard."
Found this on-line hope it helps...I go by throttle response and seat of my pants method myself numbers are just numbers
"SAE (Society of Automotive Engineers), USA. Power is corrected to reference conditions of 29.23 InHg (99 kPa) of dry air and 77 F (25°C). This SAE standard requires a correction for friction torque. Friction torque can be determined by measurements on special motoring dynamometers (which is only practical in research environments) or can be estimated. When estimates must be used, the SAE standard uses a default Mechanical Efficiency (ME) value of 85%. This is approximately correct at peak torque but not at other engine operating speeds. Some dynamometer systems use the SAE correction factor for atmospheric conditions but do not take mechanical efficiency into consideration at all (i.e. they assume a ME of 100%).
STD or STP. Another power correction standard determined by the SAE. This standard has been stable for a long time and is widely used in the performance industry. Power is corrected to reference conditions of 29.92 InHg (103.3 kPa) of dry air and 60 F (15.5°C). Because the reference conditions include higher pressure and cooler air than the SAE standard, these corrected power numbers will always be about 4 % higher than the SAE power numbers. Friction torque is handled in the same way as in the SAE standard."
Found this on-line hope it helps...I go by throttle response and seat of my pants method myself numbers are just numbers
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