Dyno results
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Joined: Jul 2001
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From: Hammer Lane
The only worldwide power correction standards at this time are the ones determined by ISO. For internal combustion engines in road vehicles, this is the ISO 1585 standard. The current SAE J 1349 and ECE standards are nearly identical to the ISO 1585 standard.
*SAE -- The SAE standard applied is a modified version of the SAE J1349 standard of June 1990. 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%). SuperFlow uses a more sophisticated algorithm for calculating friction torque, based on a summary of thousands of friction power tests performed by the automotive industry. This proprietary algorithm estimates friction torque as a function of piston speed and engine displacement.
The "SAE corrected" power numbers indicated by your SuperFlow system are thus more accurate estimates of engine power output under reference conditions than what other systems using no ME correction or using a fixed ME of 85% will provide.
NOTE Should you prefer to apply a fixed ME of 85%, you will only need to modify the SAE Correction factor calculation using the channel configuration editor.
*STP -- The STP (also called STD) standard is 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. Once again, this means the STP corrected power displayed by your SuperFlow test system will be more accurate than power numbers obtained using a default Mechanical Efficiency of 100% or 85%.
*ECE -- The ECE standard is based on the European Directives. Power is corrected to reference conditions of 99 kPa (29.23 InHg) of dry air and 25°C (77 F). Friction torque is not taken into consideration at all.
In 1995, a new Directive (95/1/EEC) regarding test methods for motorcycles was published. The CycleDyn uses some of the information provided in this standard as reference for driveline loss calculations.
*DIN -- The DIN standard is determined by the German automotive industry. Power is corrected to reference conditions of 101.3 kPa (29.33 InHg) of dry air and 20°C (68 F). With the advent of European legislation and standards, national standards such as the DIN (formerly widely used) are now less significant.
*SAE -- The SAE standard applied is a modified version of the SAE J1349 standard of June 1990. 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%). SuperFlow uses a more sophisticated algorithm for calculating friction torque, based on a summary of thousands of friction power tests performed by the automotive industry. This proprietary algorithm estimates friction torque as a function of piston speed and engine displacement.
The "SAE corrected" power numbers indicated by your SuperFlow system are thus more accurate estimates of engine power output under reference conditions than what other systems using no ME correction or using a fixed ME of 85% will provide.
NOTE Should you prefer to apply a fixed ME of 85%, you will only need to modify the SAE Correction factor calculation using the channel configuration editor.
*STP -- The STP (also called STD) standard is 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. Once again, this means the STP corrected power displayed by your SuperFlow test system will be more accurate than power numbers obtained using a default Mechanical Efficiency of 100% or 85%.
*ECE -- The ECE standard is based on the European Directives. Power is corrected to reference conditions of 99 kPa (29.23 InHg) of dry air and 25°C (77 F). Friction torque is not taken into consideration at all.
In 1995, a new Directive (95/1/EEC) regarding test methods for motorcycles was published. The CycleDyn uses some of the information provided in this standard as reference for driveline loss calculations.
*DIN -- The DIN standard is determined by the German automotive industry. Power is corrected to reference conditions of 101.3 kPa (29.33 InHg) of dry air and 20°C (68 F). With the advent of European legislation and standards, national standards such as the DIN (formerly widely used) are now less significant.
I've always been told SAE; and, until recently, that's what was most commonly compared here on this site as well. It's hard to compare one vehicle to another, from one area to another, without using the same correction factor. If there is no desire for such a comparison, why not just post a net gain in percentages, from one dyno session to another, and keep the peak numbers to ones self?
With the same parts installed, tuner 1 gets 485 rwhp and tuner 2 gets 504 rwhp? Which number impresses you more? Which tuner, with all other things being equal, gets your business? Which tuner would you pay just a little more to benefit from his 'superior' tuning skills? How upset would you be to find out that the difference in tuners is correction factors and not talent?
I say SAE is the way to go, unless you're trying to sell something.
**Not trying to start a flame war here. This post has not been a shot at anyone in particular. Most of the major performance aftermarket parts suppliers use STD numbers to inflate the benefits of buying their products. It's an industry wide practice. Car enthusiasts and racers, most often use SAE. At least, that's the observation I've made.**