I have noticed alot of people posting SAE and STD numbers alike. When I get my dyno week, should I request SAE numbers or STD numbers? Some of my friends say STD should be used because that is what the car puts down plain and simple. Others say SAE because it gives you an idea of how it compares to other cars across the country. So which one should I use?
SAE or STD when using a dyno??
- Thread starter Juiced-03
- Start date
SAE
ditto, sae.
Thats what I figured. My buddy with his ported h/c/LS6 Intake LS1 with a 150 shot put down 535hp (STD). He had requested STD because he said it is a more accurate number of what the car is capable of?? He said SAE numbers dont matter because he is not comparing his car to others.
What do you think 535 STD hp would be in SAE terms?
What do you think 535 STD hp would be in SAE terms?
SAE uses a standard for temp, humidity, altitude, etc. So when comparing to others all factors are the same. STD is what the car actually makes on that day with all the current conditions. I don't think you can convert the number from STD to SAE unless you are at the dyno.
no , not at all. if he dynoed recently , in this good , cold weather. he can have as low as 500 sae. i dynoed 2 months ago, on a pretty good day my STD #'s were 452 rwhp and 466 rwtq . my SAE #'s were 438 rwhp and 448rwtq.
Something interesting here, for some reason, maybe it has to do with altitude, but my STD numbers are lower than my SAE numbers, go figure!
I hope this clears some confusion up, this info was written by a mamber of Tampa Bay SVTOA, not myself, but rather than put it in my words, I will use his... Thanx Rob...
1) UNCORRECTED format which measures the Exact power and Torque generated at the wheels as you spin the Dyno rollers at that moment on that day. It is important to know here, This is only measure to determine true RWHP delivered to the wheels that day, all the other formats CORRECT the data based on the environmental (weather) conditions (explained below).
2) CORRECTED using SAE or STD or STP Correction standards which is a Calculated NOT a measured reading for HP and Torque. CORRECTED means what is Actually measured on that day is then passed thru some formulas to CORRECT the readings to match a single Standardized Air Temperature, Barometric Pressure, Humidity, Altitude and Dyno Friction. The purpose being that on one day the Temperature is for example 70 degrees. The next day it is 85 degrees. At 85 degrees the car will make less RWHP than on the day when it was 70 degrees because is was hotter out. The theory here is that, as we put new performance parts on our car, we need a Consistent way to measure any gain (or loss) without confusing the issue with Environmental factors such as temperature and humidity that have a DEFINITE affect on RWHP, so we get more accurate readings for the Net RWHP gain made by a Pulley change or Headers, etc..
The most common correction factor is SAE (explained below). STD and STP (almost identical to each other STD/STP) is very commonly used in the performance industry also. Whatever you pick as a correction factor, you will want to stick with it as you continually Dyno your car over time. That’s because you want to be able to tell over time, a consistent way to measure performance gains made by upgrades you made to your car and this is the only way to do it.
STD and STP generally come out with about 4 % higher numbers than SAE since the temperature in the standard is lower in STD than in SAE. It still makes no difference what you use as long as you are consistent. If you use SAE then always use SAE. If you use STD then always stick to STD.
Power Correction Factors-
The power output of an internal combustion engine is significantly influenced by barometric pressure, ambient air temperature, and air humidity.
· lower ambient barometric pressure reduces the density of the air, thus reduces the amount of oxygen filling the cylinder for each cycle, resulting in lower power output. Conversely, higher barometric pressure increases power.
· lower ambient air temperature results in increased density of the air, thus increases the amount of oxygen filling the cylinder for each cycle, resulting in higher power output.
Conversely, higher air temperature reduces power output.
· lower air humidity (= less water vapor) leaves more room for oxygen per cubic foot of air, thus increases the amount of oxygen filling the cylinder for each cycle, resulting in higher power output. Conversely, higher air humidity reduces power output.
NOTE -- Power correction standards try to estimate what engine power would be under reference conditions. They cannot actually calculate exactly what power output would be. The greater the difference between the ambient conditions during the test and the reference conditions, the greater the error in the estimate. Most power correction standards include limits on their applicability. This limit is typically +/- 7%. This means if the correction factor is greater than (>) 1.07 or less than (<) 0.93, the corrected power numbers are not officially considered to be acceptable, and the test should be performed again under conditions which are closer to the reference conditions.
NOTE -- Power corrections are only valid for Wide Open Throttle (WOT) tests. You should disregard corrected power numbers for any test performed under partial throttle conditions. The default configurations supplied with most Dyno’s include power corrections to the following standards: SAE, STP, ECE, DIN.
· 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%).
· 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.
· 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.
·
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.
NOTE There is a tendency for all those standards to converge. 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.
ROB
Again, I must give credit to Rob_Cooper of TBSVTOA for doing the research and writing the artical, Thanx Rob!!!
For comparison I have my numbers from my dyno, the temp was 55.5* barometer- 30.15 and humidity was 39%. on a DynoJet
UNCORRECTED 482 HP/ 484 TQ
STD CORRECTED 470 HP/ 472 TQ
SAE CORRECTED 455 HP/ 457 TQ
Those are the 3 pull factors on the same pull.
Craiger
1) UNCORRECTED format which measures the Exact power and Torque generated at the wheels as you spin the Dyno rollers at that moment on that day. It is important to know here, This is only measure to determine true RWHP delivered to the wheels that day, all the other formats CORRECT the data based on the environmental (weather) conditions (explained below).
2) CORRECTED using SAE or STD or STP Correction standards which is a Calculated NOT a measured reading for HP and Torque. CORRECTED means what is Actually measured on that day is then passed thru some formulas to CORRECT the readings to match a single Standardized Air Temperature, Barometric Pressure, Humidity, Altitude and Dyno Friction. The purpose being that on one day the Temperature is for example 70 degrees. The next day it is 85 degrees. At 85 degrees the car will make less RWHP than on the day when it was 70 degrees because is was hotter out. The theory here is that, as we put new performance parts on our car, we need a Consistent way to measure any gain (or loss) without confusing the issue with Environmental factors such as temperature and humidity that have a DEFINITE affect on RWHP, so we get more accurate readings for the Net RWHP gain made by a Pulley change or Headers, etc..
The most common correction factor is SAE (explained below). STD and STP (almost identical to each other STD/STP) is very commonly used in the performance industry also. Whatever you pick as a correction factor, you will want to stick with it as you continually Dyno your car over time. That’s because you want to be able to tell over time, a consistent way to measure performance gains made by upgrades you made to your car and this is the only way to do it.
STD and STP generally come out with about 4 % higher numbers than SAE since the temperature in the standard is lower in STD than in SAE. It still makes no difference what you use as long as you are consistent. If you use SAE then always use SAE. If you use STD then always stick to STD.
Power Correction Factors-
The power output of an internal combustion engine is significantly influenced by barometric pressure, ambient air temperature, and air humidity.
· lower ambient barometric pressure reduces the density of the air, thus reduces the amount of oxygen filling the cylinder for each cycle, resulting in lower power output. Conversely, higher barometric pressure increases power.
· lower ambient air temperature results in increased density of the air, thus increases the amount of oxygen filling the cylinder for each cycle, resulting in higher power output.
Conversely, higher air temperature reduces power output.
· lower air humidity (= less water vapor) leaves more room for oxygen per cubic foot of air, thus increases the amount of oxygen filling the cylinder for each cycle, resulting in higher power output. Conversely, higher air humidity reduces power output.
NOTE -- Power correction standards try to estimate what engine power would be under reference conditions. They cannot actually calculate exactly what power output would be. The greater the difference between the ambient conditions during the test and the reference conditions, the greater the error in the estimate. Most power correction standards include limits on their applicability. This limit is typically +/- 7%. This means if the correction factor is greater than (>) 1.07 or less than (<) 0.93, the corrected power numbers are not officially considered to be acceptable, and the test should be performed again under conditions which are closer to the reference conditions.
NOTE -- Power corrections are only valid for Wide Open Throttle (WOT) tests. You should disregard corrected power numbers for any test performed under partial throttle conditions. The default configurations supplied with most Dyno’s include power corrections to the following standards: SAE, STP, ECE, DIN.
· 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%).
· 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.
· 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.
·
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.
NOTE There is a tendency for all those standards to converge. 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.
ROB
Again, I must give credit to Rob_Cooper of TBSVTOA for doing the research and writing the artical, Thanx Rob!!!
For comparison I have my numbers from my dyno, the temp was 55.5* barometer- 30.15 and humidity was 39%. on a DynoJet
UNCORRECTED 482 HP/ 484 TQ
STD CORRECTED 470 HP/ 472 TQ
SAE CORRECTED 455 HP/ 457 TQ
Those are the 3 pull factors on the same pull.
Craiger
Last edited:
scott - you only get 14 # of boost from a 20+ # setup, you run low 12's with a 10 sec setup, and your sae and std #'s are backwards!! your whole state is a$$ backwards!! you have to move man!!! :lol: :lol: :lol:
j/k bro!! :beer:
I think we should all own up here and just post SAE numbers, which are the most widely accepted in this country. Honestly, the only reason people and tuners use STD numbers is that they are usually 2 to 4% higher than SAE.
If all you're doing is comparing your own car before and after a mod, it doesn't make any real difference, but if you want some comparison to other peoples' numbers just use SAE.
If all you're doing is comparing your own car before and after a mod, it doesn't make any real difference, but if you want some comparison to other peoples' numbers just use SAE.
tampaSVT03,
Thanks for the explanation. Lot of typing for you, but very informative....
Thanks for the explanation. Lot of typing for you, but very informative....
PhillyCobra....agreed totally.
Is that JD's dyno? Looks familiar......been there a few times myself!!! :beer:
Is that JD's dyno? Looks familiar......been there a few times myself!!! :beer:
I downloaded Runviewer7 from the dynojet website and am able to view all my dyno runs and change the correction factors from SAE, STD, etc..
I think it takes the initial values inputted by the dyno shop, and uses them as the basis for all the other conversions.
I think it takes the initial values inputted by the dyno shop, and uses them as the basis for all the other conversions.
can someone tell me why my SAE numbers are higher than my uncorrected numbers. is this correct or what. test conditions were 61 deg. 31%humidity 30.29 barometer.
466hp & 455 trq SAE
442hp & 431 trq uncorrected
thanks
brandon
466hp & 455 trq SAE
442hp & 431 trq uncorrected
thanks
brandon
get all three, Actual, so you know what your car is making that day, STD and SAE. SAE if you have to pick one
Users who are viewing this thread
