Thread: Verifying Actual Horsepower
02-27-2006, 12:11 PM #1
Verifying Actual Horsepower
With the reflashed ECU's, Les' B kits, Vortech S/C impellers, and all of the other bolt on mods, how does one check where the actual Horsepower of their ski lies? I am sure it is not as simple as just adding the "claimed" numbers that each mod gives. Just as I am pretty sure my GTX did not come out of the factory with the full 185 hp.
02-27-2006, 01:37 PM #2
i wish there was a way to dyno test our skis also
02-27-2006, 02:00 PM #3
02-27-2006, 02:01 PM #4
02-27-2006, 02:18 PM #5Originally Posted by BOATADDICT
02-27-2006, 02:20 PM #6
I think that someone on here has one. I forget who though.
02-27-2006, 02:27 PM #7
02-27-2006, 02:28 PM #8
If it bolts to the pump would the RXP rip it off the hull?
02-27-2006, 03:38 PM #9
This curve will get you going.
Your ski has a built in dyno of sorts. The cool part with the ski dyno, is you can measure actual horsepower that is transferred into the water.
Horsepower is a function of RPMxTorque.
HP Primer: http://www.epi-eng.com/BAS-PwrTrq.htm
If you increase RPM in that equation, assuming torque stays the same, you make more HP. Theres no way around it.
In your jet pump, torque does not stay the same for a given RPM, torque increases as well with the RPM, so its not as simple as increasing the RPM value in that equation. However, by modeling the pump torque curve, you can get a good approximation of HP change over an RPM change.
Anyway, you plug in the numbers into the magic formula, assuming 208.9hp at 8100 RPM with a stock prop, you get:
This is a rough estimate, but should be rather close. These numbers are only good for a stock prop. If you run a less steep pitch prop, then your HP is lower for a given RPM. If you run a steeper than stock prop, then your HP is higher.
02-28-2006, 04:18 AM #10
How are you attributing hull drag, associated with weight, not to mention engine placement, and a whole host of other issues such as pump liner condition, efficiency of pump inlet tract (riva,r/d,stock,etc)???
Then, let's just throw in the fact that hulls and friction are NOT LINEAR, neither is pump efficiency.
God forbid we start talking things like rider weight. That one always leaves me with less horsepower.
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