Dyno Correction Factors etc.

[NAH]

Chaps, this might be a little off topic, but I am trying to establish the many & sublte differences between chassis dyno's (correction factors, calibration etc).

Does anyone know what is used in Oz (e.g. DIN 70020, SAE etc)?

Also, I have heard that the value of DIN is different in Oz to that in the rest of the world (Aus DIN = 2.333% higher) - is this correct?

Finally, is there any info on the calcualtion methods employed by the various dyno manufacturers? I have spoken to one who suggest that such info was privileged.

Any help gratefully received.

Neil.

[MCG]

The older SAE J607 (STD) 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 (SAE) of 77°F (25°C) day with 0% humidity and a barometric pressure of 29.234 in-Hg (99 KPa). Also the EEC 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).

[TAQuickness]

good thing they standardized it....

[SSpdDmon]

...and we wonder why government f**ks up all of the time. We can't even agree on a dyno standard. LOL

[dfe1]

...and we wonder why government f**ks up all of the time. We can't even agree on a dyno standard. LOL You should be ashamed of yourself, talking that way about the government-- don't you know it's not polite to pick on the handicapped??

As for the dyno "standards", the 29.92, 60-degree, dry air correction is generally known as SAE standard correction and was commonly used universally, "back in the day". Since those numbers don't accurately reflect the power an engine makes when actually installed in a vehicle, the SAE net standard was developed. In addition to a different set of arometric/temperature standards, SAE net also specifies that the engine be tested with normal accessories installed. Apparently, not everyone agrees with the SAE net factors, so there are a number of others (DIN, JIS, etc). The SAE standards typically apply to power measurements made on an engine dyno. I'm not sure what the "standard" is for chassis dyno testing.

[NAH]

Thanks chaps. Anyone know why Oz HP is higher than Rest of World?

[TAQuickness]

They do some crazy $hit down under ;)

[Redline Motorsports]

Not for nothing but..........I have learned to not get to interested in the numbers but rather the gains. The dyno comparison debate is a never ending circle jerk.

I do a have this link to this site that has some cool calculations for correction factors and DA;

http://wahiduddin.net/calc/cf.htm

Howard

[NAH]

The numbers game is definitely a hot debate, but as an engineer (electrical not mechancial), I am intrigued to know how a calcualtion or measurement of power can be different depending upon which side of the equator one heralds.

Oh well, I'm off to measure some inches of mercury.