How Impeller pitch works?

[RustySeaRustyDoo]

Does anyone have a link or illustration how the pitch works on an impeller and some explanation on what each pitch gives???

I would really like to have some more knowledge in this area..and I know some others would too...

Thanks in advance.

[RustySeaRustyDoo]

So....nobody knows??? Maybe there are more people that dont know then I thought. Someone has to know something....

[Yuji]

Leading Edge: This is the part of the blade facing toward the front of the ski and first contacts the incoming flow, it's also the first number when describing an impeller pitch ie. 14/20.
Trailing Edge: This is the part of the blade where the water exits and is the second number in pitch description ie 14/20

If you increase pitch you increase the load on the pump and generate more water flow, this results in a decrease in RPM's.
If you decrease pitch you reduce load thus allowing the motor to rev and increase RPM's

A 14/20 impeller pitch is what they call progressive pitch and this is what gives you the best of both worlds, maximum thrust and pump flow from a dead start to wide open throttle. You have to take into account that the pump/motor demands change as you accelerate. As vehicle speed increases the pump naturally flows more water and the motor doesn't work as hard to maintain momentum. This allows you to add pitch to the trailing edge and gain mph, keeping in mind that you can only add so much pitch before you rpms begin to drop (flowing more water then the motor is capable of). The same applies to the leading edge...you want maximum thrust out of the hole without cavitation (need more pitch) or bogging the motor by overloading it (too much pitch)

The goal is to load the pump as much as possible generating maximum thrust without inducing cavitation and then maintain optimum max rpm for a given motor ie/ stock RXP = 8100rpm.

Does that make sense?

This is my take on it...If there's something I've got wrong in the description please post

Here's the "how to impeller pitching" thread...check it out
http://greenhulk.net/forum/viewtopic.php?t=3088

[RustySeaRustyDoo]

Thanks for taking the time to respond Yugi ...Im getting a better understanding now...

[jawz]

That's one of the most complicated Questions you can ask... And anyone that answers you will not know 100 percent of the mastery of pitching. I can tell you the pumps we presently have are VERY ineffiecient( 50%) and small changes can add several mph. And sending them out to get speed is a year long process. Look at it from an effieciency stand point. Your always limited by how much water you can process.

[North49]

Thanks for that answer....this is not a topic I have much knowledge about and your answer definitely helps.