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Old 12-20-2004, 07:05 PM   #46
Finnattic
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Post Lowdown On Dyno's

Differences of "SAE" and "Standard Corrected"

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It seems I've answered my own question. Long story short:

"SAE" : This standard makes it seem that the test was conducted at 77oF, 29.23 in. of Hg pressure, and a humidity of zero.

"Standard Corrected" : is popular with aftermarket manufacturers because it uses a higher pressure and a lower temperature (denser air), thus inflating the horsepower numbers.


I found a little more info that seems consistent from what has been noted in this discussion...

This is a really informative good read...

It seems SAE is more for naturally aspirated engines and not for say a engine with a turbo. Learning more and more. That's what's it's all about...

"Once the test is complete, the computer "corrects" the data. Environmental conditions such as temperature and atmospheric pressure have a significant effect on the horsepower that an internal combustion engine produces. Fortunately, this effect is well understood and easy for a computer to account for. In order to make useful horsepower comparisons, most test results are tweaked so that it appears that the test was conducted at a specific temperature, pressure, and humidity. In the United States, the most common correction factor is SAE J1349. This standard makes it seem that the test was conducted at 77oF, 29.23 in. of Hg pressure, and a humidity of zero. If you want your horsepower corrected to a different standard, such as EEC (popular in Japan), DIN (popular in Germany), or "standard corrected," you must let me know before I print the results. Remember, the standards use different atmospheric conditions and they will all return different horsepower values. "Standard corrected" is popular with aftermarket manufacturers because it uses a higher pressure and a lower temperature (denser air), thus inflating the horsepower numbers. If you want bragging rights over your peers, make sure all of you use the same standard. You certainly don't want to be seen whipping out your calculators before you go street racing.

You will receive a printout of your vehicle's test results which will consist of a graph plotting horsepower and torque vs. engine rpm (or speed, if you choose.) You will receive a graph plotting your air / fuel ratio vs. rpm if you elected to do such a run, and you will also receive a text printout of the hp and torque vs. rpm or speed for each run."


http://www.bristoldyno.com/info/procedure.htm

http://www.sdsefi.com/techdynojet.htm
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