Foot lbs or Pound ft = torque?
HD EFI Guru
Joined: Jan 2008
Posts: 4,492
Likes: 4,778
Well if your going to get into it, then one needs to know if it's measure in SAE, STD, DIN ect. and on a DynoJet , SuperFlow, Mustang ect as they all use various Fudge factors just like changing the size and shape of the picture screws the way it looks.
Grand HDF Member
Joined: Sep 2017
Posts: 4,359
Likes: 1,219
From: Dubuque, IA
But since you bring it up, there's some misconceptions with the sae/std thing too. The difference isn't always all that much and SOMETIMES sae can be higher than std.
The difference in dynos is out of my league except I know there are differences.
STD for the same run in my case was 130/129. A difference of 3/3.
In dyno class I used to graph the same run in all the different correction factors and ask which was the best. 99.9% of the people looked at lines and didn't read data -hence they didn't realize it was the same run presented in different factors.
Grand HDF Member
Joined: Sep 2017
Posts: 4,359
Likes: 1,219
From: Dubuque, IA
Correction factors are there to actually "level the playing field" so to speak under varying conditions. Unfortunately they can also be used for less legitimate purposes to boost numbers.
I know I'm not telling some of you anything new.
I think the SAE/STD difference is a little more complicated than just a difference of a set % but the 3 - 4% is probably pretty close a lot of times. What conditions would actually make SAE numbers larger than STD I can't really explain either. Not precisely anyway. It was explained to me at one time years ago but I'm not sure how to explain it. It has to do with conditions like temp, humidity, altitude, etc. There are times, conditions, etc. where STD is more of an accurate representation of what's being produced power wise than SAE tho.
The closer actual conditions are to that used by SAE the closer the two will be is how I understand it.
Based on actual conditions at the time, mine was 130/129. But based on a certain set of conditions SAE uses it was 127/126. So which is actually an accurate representation? Not so simple I say. What makes SAE "right" and STD "wrong"?
Came across this explanation.
Simple, SAE is a prediction of what your HP/torque will be at a certain, accepted weather conditon. STD is what your car is actually putting out right at that exact moment.
STD numbers will be higher if the conditions are better than SAE (ie colder, less humid, high pressure), and conversely lower when the conditions are worse than SAE.
I know I'm not telling some of you anything new.
I think the SAE/STD difference is a little more complicated than just a difference of a set % but the 3 - 4% is probably pretty close a lot of times. What conditions would actually make SAE numbers larger than STD I can't really explain either. Not precisely anyway. It was explained to me at one time years ago but I'm not sure how to explain it. It has to do with conditions like temp, humidity, altitude, etc. There are times, conditions, etc. where STD is more of an accurate representation of what's being produced power wise than SAE tho.
The closer actual conditions are to that used by SAE the closer the two will be is how I understand it.
Based on actual conditions at the time, mine was 130/129. But based on a certain set of conditions SAE uses it was 127/126. So which is actually an accurate representation? Not so simple I say. What makes SAE "right" and STD "wrong"?
Came across this explanation.
Simple, SAE is a prediction of what your HP/torque will be at a certain, accepted weather conditon. STD is what your car is actually putting out right at that exact moment.
STD numbers will be higher if the conditions are better than SAE (ie colder, less humid, high pressure), and conversely lower when the conditions are worse than SAE.
Last edited by 60Gunner; Apr 24, 2022 at 08:35 AM.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,930
Likes: 8,033
From: poway
Correction factors are there to actually "level the playing field" so to speak under varying conditions. Unfortunately they can also be used for less legitimate purposes to boost numbers.
I know I'm not telling some of you anything new.
I think the SAE/STD difference is a little more complicated than just a difference of a set % but the 3 - 4% is probably pretty close a lot of times. What conditions would actually make SAE numbers larger than STD I can't really explain either. Not precisely anyway. It was explained to me at one time years ago but I'm not sure how to explain it. It has to do with conditions like temp, humidity, altitude, etc. There are times, conditions, etc. where STD is more of an accurate representation of what's being produced power wise than SAE tho.
The closer actual conditions are to that used by SAE the closer the two will be is how I understand it.
Based on actual conditions at the time, mine was 130/129. But based on a certain set of conditions SAE uses it was 127/126. So which is actually an accurate representation? Not so simple I say. What makes SAE "right" and STD "wrong"?
Came across this explanation.
Simple, SAE is a prediction of what your HP/torque will be at a certain, accepted weather conditon. STD is what your car is actually putting out right at that exact moment.
STD numbers will be higher if the conditions are better than SAE (ie colder, less humid, high pressure), and conversely lower when the conditions are worse than SAE.
I know I'm not telling some of you anything new.
I think the SAE/STD difference is a little more complicated than just a difference of a set % but the 3 - 4% is probably pretty close a lot of times. What conditions would actually make SAE numbers larger than STD I can't really explain either. Not precisely anyway. It was explained to me at one time years ago but I'm not sure how to explain it. It has to do with conditions like temp, humidity, altitude, etc. There are times, conditions, etc. where STD is more of an accurate representation of what's being produced power wise than SAE tho.
The closer actual conditions are to that used by SAE the closer the two will be is how I understand it.
Based on actual conditions at the time, mine was 130/129. But based on a certain set of conditions SAE uses it was 127/126. So which is actually an accurate representation? Not so simple I say. What makes SAE "right" and STD "wrong"?
Came across this explanation.
Simple, SAE is a prediction of what your HP/torque will be at a certain, accepted weather conditon. STD is what your car is actually putting out right at that exact moment.
STD numbers will be higher if the conditions are better than SAE (ie colder, less humid, high pressure), and conversely lower when the conditions are worse than SAE.
This shows little you really know about what they represent..
SAE:
"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.
STD:
STD is Another power correction standard determined by the SAE. Power is corrected to reference conditions of 29.92 InHg (103.3 kPa) of dry air and 60 F (15.5°C)."
"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.
STD:
STD is Another power correction standard determined by the SAE. Power is corrected to reference conditions of 29.92 InHg (103.3 kPa) of dry air and 60 F (15.5°C)."
"STD power" is "not actual" "Actual power" is "actual power" Now actual power can be higher or lower than corrected temps like STD and SAE depending on ambient conditions.
Where do you get this information from?
Last edited by Max Headflow; Apr 24, 2022 at 09:10 AM. Reason: Added some stuff
Grand HDF Member
Joined: Sep 2017
Posts: 4,359
Likes: 1,219
From: Dubuque, IA
I said it's something I just came across for the sake of discussion. How accurate it is I don't know. But what makes one right and one wrong based on actual conditions vs a set of predetermined conditions?
I don't know. That's why I post both. The difference between them was more like 2%.
So one uses a lower temp, humidity, etc. standard than the other? But both use these correction standards?
What's the difference between dynos and what makes one more right than the other?
I don't know. That's why I post both. The difference between them was more like 2%.
So one uses a lower temp, humidity, etc. standard than the other? But both use these correction standards?
What's the difference between dynos and what makes one more right than the other?
Last edited by 60Gunner; Apr 24, 2022 at 10:33 AM.
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Tourer
Joined: May 2006
Posts: 269
Likes: 100
From: Florida
Here are my notes from training days in the outboard motor business. Years back in my younger days I ran dynos while at OMC Engineering, makers of Johnson and Evinrude outboards. Today the industry uses ISO or ICOMIA dyno procedures.
There are two main correction factors used to standardize results with varying
atmospheric conditions: SAE J-1349, which adjusts the prevailing
test conditions to 77 degrees F and 29.92 in-Hg of barometric
pressure; and SAE J-607 (also known as Standard Temperature
and Pressure or STP for short), which corrects the test data to 60
degrees F and 29.23 in-Hg of barometric pressure.
Most of the OEM manufacturers use SAE J-1349 to rate engine power output,
measured at the flywheel. Most magazines, race engine builders and
aftermarket companies use SAE J-607 STP correction factors when
quoting dynamometer horsepower figures. The difference between the
two correction factors is generally 5 percent as a result of the STP factor
having a colder air correction factor.
ICOMIA Standard No. 28-83
Power measurements and declarations for
marine propulsion engines and propulsion systems
ISO – International Organization of Standards
• ISO 3046/1 -- Reciprocating Internal Combustion Engines:
o Performance--Part 1: Standard Reference Conditions and Declarations of Power, Fuel Consumption
• ISO 3046/2 -- Reciprocating Internal Combustion Engines:
o Performance--Part 2: Test Methods
• ISO 3046/3 -- Reciprocating Internal Combustion Engines:
o Performance--Part 3: Test Measurements
There are two main correction factors used to standardize results with varying
atmospheric conditions: SAE J-1349, which adjusts the prevailing
test conditions to 77 degrees F and 29.92 in-Hg of barometric
pressure; and SAE J-607 (also known as Standard Temperature
and Pressure or STP for short), which corrects the test data to 60
degrees F and 29.23 in-Hg of barometric pressure.
Most of the OEM manufacturers use SAE J-1349 to rate engine power output,
measured at the flywheel. Most magazines, race engine builders and
aftermarket companies use SAE J-607 STP correction factors when
quoting dynamometer horsepower figures. The difference between the
two correction factors is generally 5 percent as a result of the STP factor
having a colder air correction factor.
ICOMIA Standard No. 28-83
Power measurements and declarations for
marine propulsion engines and propulsion systems
ISO – International Organization of Standards
• ISO 3046/1 -- Reciprocating Internal Combustion Engines:
o Performance--Part 1: Standard Reference Conditions and Declarations of Power, Fuel Consumption
• ISO 3046/2 -- Reciprocating Internal Combustion Engines:
o Performance--Part 2: Test Methods
• ISO 3046/3 -- Reciprocating Internal Combustion Engines:
o Performance--Part 3: Test Measurements
Last edited by billgran; Apr 24, 2022 at 11:41 AM.
Grand HDF Member
Joined: Sep 2017
Posts: 4,359
Likes: 1,219
From: Dubuque, IA
Here are my notes from training days in the outboard motor business. Years back in my younger days I ran dynos while at OMC Engineering, makers of Johnson and Evinrude outboards. Today the industry uses ISO or ICOMIA dyno procedures.
There are two main correction factors used to standardize results with varying
atmospheric conditions: SAE J-1349, which adjusts the prevailing
test conditions to 77 degrees F and 29.92 in-Hg of barometric
pressure; and SAE J-607 (also known as Standard Temperature
and Pressure or STP for short), which corrects the test data to 60
degrees F and 29.23 in-Hg of barometric pressure.
Most of the OEM manufacturers use SAE J-1349 to rate engine power output,
measured at the flywheel. Most magazines, race engine builders and
aftermarket companies use SAE J-607 STP correction factors when
quoting dynamometer horsepower figures. The difference between the
two correction factors is generally 5 percent as a result of the STP factor
having a colder air correction factor.
There are two main correction factors used to standardize results with varying
atmospheric conditions: SAE J-1349, which adjusts the prevailing
test conditions to 77 degrees F and 29.92 in-Hg of barometric
pressure; and SAE J-607 (also known as Standard Temperature
and Pressure or STP for short), which corrects the test data to 60
degrees F and 29.23 in-Hg of barometric pressure.
Most of the OEM manufacturers use SAE J-1349 to rate engine power output,
measured at the flywheel. Most magazines, race engine builders and
aftermarket companies use SAE J-607 STP correction factors when
quoting dynamometer horsepower figures. The difference between the
two correction factors is generally 5 percent as a result of the STP factor
having a colder air correction factor.
I had a difference of 2.3%.
is it true uncorrected is never accepted? If so, why? Does it result in higher or lower numbers?
Thanks. I'm trying to understand why one is considered more accurate in ALL circumstances.
Last edited by 60Gunner; Apr 24, 2022 at 10:53 AM.