Please explain.....

Fox

Fox

God im so pants at skiing
Location
Isle of Skye, Scotland.
Can anybody please clearly explain exactly what the numbers mean when looking at an impeller? 12/17. Is that somit to do with pitch and diameter of the impeller? Plus if so, the higher the pitch number does that mean better acceleration or better top speed?

Thank you.
 
keefer

keefer

T1
Location
Tennessee
The numbers refer to the pitch angle of the blades. The first number 12 is the degree angle of the leading edges. The last number 17 is the degree angle of the trailing edges. This type of progressive pitch impeller has been popular for quite some time. The thinking is that you can get the benefits of both low end performance without sacrificing too much top end performance. Like the best of both worlds scenario. Diameter of the impeller is determined by what size pump you have. I.E. 144mm for SJ, 140 for FX/1 etc. The inner hub diameter varies by prop model and manufacturer. The leading edge of the blade, overlap, & inner hub shape & size determine how the impeller will work. As you can imagine there are many possibilites and you need to decide what type of riding you are doing along with engine HP and other setup factors before you choose the right one.
 
Shonuff

Shonuff

I've got the glow
Site Supporter
Location
Memphis
The first number is the leading edge pitch. This indicates the amount of water being scooped into the pump. A lower number means a bigger scoop, which means more water goes into the pump. The second number is the trailing edge. This is the edge that accelerates the water, a higher number means more top end. (if your motor can pull it)

The "spread" is the difference between the 2 numbers. The bigger the difference between the numbers, the greater the amount of water that gets processed thru the pump. The bigger the spread (or window) however, the more torque you need to be making to pull the prop through this greater volume of water.
 
Mouthfulloflake

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
dang man.

you are smarter than I thought.



Shonuff said:
The first number is the leading edge pitch. This indicates the amount of water being scooped into the pump. A lower number means a bigger scoop, which means more water goes into the pump. The second number is the trailing edge. This is the edge that accelerates the water, a higher number means more top end. (if your motor can pull it)

The "spread" is the difference between the 2 numbers. The bigger the difference between the numbers, the greater the amount of water that gets processed thru the pump. The bigger the spread (or window) however, the more torque you need to be making to pull the prop through this greater volume of water.
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