SAE J1349 - Corrected Horsepower
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09-27-2006, 12:22 AM
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SAE J1349 - Corrected Horsepower
Corrected Horsepower Link
According to the link all engines and dyno's are corrected to one the described standards. It looks like SAE J1349 is probably the one used by Dodge. Does anyone know? In any case you can correct your power based on a number of factors, and yes there is math involved, sorry Dave.... [just kidding]
Here is a snippet:
According to the link all engines and dyno's are corrected to one the described standards. It looks like SAE J1349 is probably the one used by Dodge. Does anyone know? In any case you can correct your power based on a number of factors, and yes there is math involved, sorry Dave.... [just kidding]
Here is a snippet:
We have all seen and made claims of an engine’s horsepower. However, this stated horsepower is almost never what the engine actually made for power. How can that be? Most of the stated horsepower numbers are “Corrected” values. The correction standards were developed to discount the observed horsepower readings taken at different locations and weather conditions. It is obvious that an engine builder in Colorado could not produce as much horsepower as a shop at sea level. There is just less oxygen for the engine to burn at the higher altitude. What are less obvious are the other weather condition effects on the engine. So in order to compensate for this all advertised horsepower is “corrected” to several different industry standards.
Most of you know about Atmospheric Correction Factors that are used to compare an engines power output for one day or location to another. However, these factors can be rather confusing and even deceptive. Everybody seems to declare there engine’s horsepower as “etched in stone” number, however we also know that the engine will make very different power on different days. Excluding other factors like engine temperature and quality of fuel used, the engine output is very dependant on the amount of oxygen in the air. So the only way to compare an engine’s horsepower is to correct the output on a given day to some standard.
The most common are the SAE standards. The older J607 standard considers that the engine was run on a 60°F day with 0% humidity and a barometric pressure of 29.92 in-Hg or the newer SAE J1349 standard of 77°F (25°C) day with 0% humidity and a barometric pressure of 29.234 in-Hg (99 KPa). Also the ECE standard is the same as the SAE J1349, but does not use mechanical efficiency in the calculations. The DIN standard which corrects to 68°F (20° C) day with 0% humidity and a barometric pressure of 29.92 in-Hg (101.3 KPa) and the JIS standard corrects 77°F (25° C) day with 0% humidity and a barometric pressure of 29.234 in-Hg (99 KPa), but uses different correction curves than the others (as a substitution for using mechanical efficiency factors). Further, we have the J1995 corrects 77°F (25° C) day with 0% humidity and a barometric pressure of 29.53 in-Hg (100 KPa).
Most of you know about Atmospheric Correction Factors that are used to compare an engines power output for one day or location to another. However, these factors can be rather confusing and even deceptive. Everybody seems to declare there engine’s horsepower as “etched in stone” number, however we also know that the engine will make very different power on different days. Excluding other factors like engine temperature and quality of fuel used, the engine output is very dependant on the amount of oxygen in the air. So the only way to compare an engine’s horsepower is to correct the output on a given day to some standard.
The most common are the SAE standards. The older J607 standard considers that the engine was run on a 60°F day with 0% humidity and a barometric pressure of 29.92 in-Hg or the newer SAE J1349 standard of 77°F (25°C) day with 0% humidity and a barometric pressure of 29.234 in-Hg (99 KPa). Also the ECE standard is the same as the SAE J1349, but does not use mechanical efficiency in the calculations. The DIN standard which corrects to 68°F (20° C) day with 0% humidity and a barometric pressure of 29.92 in-Hg (101.3 KPa) and the JIS standard corrects 77°F (25° C) day with 0% humidity and a barometric pressure of 29.234 in-Hg (99 KPa), but uses different correction curves than the others (as a substitution for using mechanical efficiency factors). Further, we have the J1995 corrects 77°F (25° C) day with 0% humidity and a barometric pressure of 29.53 in-Hg (100 KPa).
