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View Full Version : HP Rating Criteria?


Riley7
10-09-2007, 10:28 AM
With all of the new big power outboards hitting the market, a question arose that I found to be very interesting: What are the criteria these engines are dyno'ed under, in terms of ambient air temp, coolant temp, air density, altitude, etc? All of these factors can have a huge impact on an engine's power output. I know for a fact I lose several MPH on a humid, 90 degree day in comparison to a cool, dry, 70 degree day. It would be VERY interesting to know if there is an industry standard for HP testing, and if not, under what conditions these engines are tested?
Stinky
10-09-2007, 10:39 AM
The industry standard is ISO 3046-1.:cool:
Riley7
10-09-2007, 10:49 AM
Stinky, could you please elaborate? Or provide a link where I can look up the specifics for myself?
Stinky
10-09-2007, 11:07 AM
Stinky, could you please elaborate? Or provide a link where I can look up the specifics for myself?

Will this do???

http://continuouswave.com/whaler/reference/ICOMIA28-83.html

:cool:
Riley7
10-09-2007, 12:30 PM
Yes, thank you. Very good info!
pyro
10-09-2007, 12:39 PM
Good info, includes everything BUT ambient air temp. It specifies how the ambient temp should be measured, but it does not specify a temperature for testing. WTF?
Stinky
10-09-2007, 03:28 PM
Good info, includes everything BUT ambient air temp. It specifies how the ambient temp should be measured, but it does not specify a temperature for testing. WTF?

Carb air as it used to be called is part of the ISO correction factor.

Basicly, you can run a motor on any day, any baro, any temp, any humidity, and the ISO correction factor will bring the HP numbers back to Standard Day.

Like right now its Baro 97.30, cell temp 25.8 C, RH 30.8, which gives a correction factor of 1.036.

So observed HP x 1.036 gives you a HP on a Standard Day.

:cool:
150aintenuff
10-09-2007, 08:07 PM
if i read this right the tests today are producing actually les HP than "standard day" as the multiplyer is above 1... belowe 1 its making more..
racer
10-09-2007, 08:40 PM
On occassion I have seen observed hp to be greater than the corrected power, not the norm but it does happen.
Stinky
10-10-2007, 07:09 AM
if i read this right the tests today are producing actually les HP than "standard day" as the multiplyer is above 1... belowe 1 its making more..

Yes, 3.6% less.

:cool:
Stinky
10-10-2007, 07:11 AM
On occassion I have seen observed hp to be greater than the corrected power, not the norm but it does happen.

Yep, I'll see a few weeks of negative correction in the winter. High baro, cold and dry.

:cool: