Speed/RPM ?

[miller19j]

All this stuff about Cyclone and HBÂ’s HP figures got me thinking about this. Can you accurately derive speed from a RPM number knowing what Impeller a jet is running assuming that the pump is in proper working order?
Lets say you have a new pump with a Berkeley A impeller turning 5100 rpm on a 19 ft boat can you estimate the speed?

[BK]

I would think there would be too many variables? How heavy and how much hook if any being two of them.

[clownpuncher]

All this has me thinking too. What about guesstamating Hp with the same info? For instance, 4300 rpm's turning an AA?

[pops1]

miller19j:
All this stuff about Cyclone and HBÂ’s HP figures got me thinking about this. Can you accurately derive speed from a RPM number knowing what Impeller a jet is running assuming that the pump is in proper working order?
Lets say you have a new pump with a Berkeley A impeller turning 5100 rpm on a 19 ft boat can you estimate the speed? 53MPH- "I like that one" give me an "A" (Thats how todays builders test them)

[Hal]

Check it out... (http://www.cpperformance.com/TechTips/dyno.htm)
This is with a stock pump/impeller. If were a tricked out pump/impeller it would take a lot more horsepower to turn that same RPM, but the pump would be doing a lot more work = speed (maybe)
There is no way you can compare Horsepower / RPM with the speed of a boat, unless each boat was exactly the same. Kinda like IROC cars were. :D
[ June 23, 2003, 08:24 PM: Message edited by: Hal ]