HP Formula

Hey is there a formula that i can use to determine my engine's HP based upon the gps reading and impeller size?

Young grasshopper, you can use the Berk Impeller Charts and cross reference your impeller cut and RPM. If your impeller has been reworked by Jack or one of the other pump guys, the Berk Chart becomes more inacurate.
You can also use the Jet Performance Calculator which can be downloaded here by clicking on the "standalone JPC" graphic.
Both this tool and the Berk charts are ballpark figures, your results will vary somewhat. If you want, I can run a desktop dyno on your engine, plot that curve against the corresponding impeller curve from the Berk charts and email you that in an excell file. Just email me the particulars on your motor and I can get you the rest.
Chris
[ September 19, 2002, 10:00 AM: Message edited by: flat broke ]

i dont have all the particulars on the motor so i'll have to try the chart.

Mike,
To a certain extent you can get the HP# correct.
The pump will hold back the engine at the max HP the engine will make at a given RPM.
If there are any inefficiencies in the pump (wear, looseness and/or air ingestion) the RPM you are now turning is going to be higher and will not be a true reading of the given HP/MPH that you are running.
The more efficient your pump is the more HP you can put to use to increase the speed/acceleration of the boat!
There is a balance that has to be found to make the most of any combination.
That is why I said "Damn?" when I heard 7100RPM and 96mph on RevnDave's Spectra. Seemed a little inefficient. Got some work to do, but I'm sure he will find it! Got alot of HP there!
Mike :)

That is right, a pump is a poor mans dyno.
[ September 19, 2002, 02:37 PM: Message edited by: Bense468 ]