Pump Pressure

I know nothing.
The little I think I know about hydraulics is
Say we are pushing 90 gallons per second
Dose a 750SX have 72HP?
If so then the pump is 110% efficient?
Since you used my Numbers...

Evidently you read right past my "very rough ballpark guesstimation" statement.

The 750 SX is rated at 63 Hp @ 6000 rpm by Kawasaki. And Kawasaki also specs 551 lb Thrust. I used 550 lbs in the calcs :oops:

The 701 Superjet is rated at 73 hp @ 6300 rpm per Yamaha. Used SJ Pump dimensions since I had that Pump handy to measure.

But Axial Flow Jet Pumps generally have efficiencies in the 90+% range anyway...o_O

Since you know "nothing", how 'bout you research how the Dynamic Water Pressure at the Pump Inlet affects the Pump Efficiency? Then comeback and explain it to us with EXACT numbers. What is the SJ 144mm Pump efficiency exactly? Or the KAW 750 SX Pump efficiency?

Some Pump Curves would be nice...

Homework due on Monday ;)
Positive pressure at the inlet is very important since water boils in a vacuum. The inlet pressure is limited by the weight and footprint of a planed hull. Any more pressure than that means water will be pushed back into the slipstream causing drag. Water won’t compress, it just gets accelerated at the outside portions of the impeller. The benefits of a larger diameter impeller are mainly seen at low hull speeds. A larger inlet equals higher pressure. A larger diameter impeller gives higher tip velocity that is needed to make pressure. The extra capacity let’s the impeller run flatter pitch and that allows better pump priming through better boundary layer formation over the front of the blades. The advantages of relatively large pumps diminish as the hulls speed and weight increase.

WFO Speedracer

A lifetime ban is like a lifetime warranty !
not sure what you are saying by posting this link. I did try to search the forum! I came up with nothing. I supposed i could have spent hours searching, but why? It's ok tho. I DON'T want this thread turning into drama!

If you are upset that i asked this question, I apologize.
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