Pump Pressure

503701

503701

Location
Oregon City Oregon
I know nothing.
The little I think I know about hydraulics is
GPMxPSI÷1714=HP
Say we are pushing 90 gallons per second
90GPSx60SEC=5400gpm
5400GPMx23PSI=124200
124100÷1714=72HP
Dose a 750SX have 72HP?
If so then the pump is 110% efficient?
 
JC-SuperJet

JC-SuperJet

Location
Texas
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 ;)
 
kevbo

kevbo

Location
dfw
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

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama

What killed the forum? How can it be revived?

to start out with and be clear although people compete and have so called " sponsors " , its stays an expensive hobby limited to the few that can afford it and furthermore live close enough to a suitable waterway..... Cost a fuel, cost of parts, cost of skis, cost of travel and lodging for...
www.x-h2o.com
 
Dorny119

Dorny119

Location
Connecticut
WFO Speedracer said:

What killed the forum? How can it be revived?

to start out with and be clear although people compete and have so called " sponsors " , its stays an expensive hobby limited to the few that can afford it and furthermore live close enough to a suitable waterway..... Cost a fuel, cost of parts, cost of skis, cost of travel and lodging for...
www.x-h2o.com
Click to expand...
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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