Freestyle Impeller pitch guide

[Joker]

Lately i have been seeing a ton of threads about "i have blah blah blah blah, what pitch impeller should i run?" Would it be possible for someone to make an impeller pitch guide that would give a general pitch for certain setups? Maybe even sticky it. I think it would help a lot of people.

Thoughts? Foreseeable problems?

 

[btmboards]

J clicked on this thread because I thought, and was hoping that that's what this was. I would love to read it. I don't I'mw anything about the props stuff but do want to.

 

[john zigler]

problem is, different brands, have different shape blades, hubs, blade over lap ect. all of this will affect pitch numbers.

just a for instance....

in a kawi 750sx, a skat standard 9/17 works well. if you go with a solas, concord, you use an 11/16. if you go with a hooker, or skat mag hub swirl, they hook up much better, and would probably want a 8/16 in the same application.

hope this makes sense.

 

[btmboards]

Could someone give me the quick "props for dummies" explanation of what each of the numbers represents. and maybe a tad of info one the hooker, mag, mag swirl.....
thanks, been trying to understand this stuff

 

[kcmasterpiece]

problem is, different brands, have different shape blades, hubs, blade over lap ect. all of this will affect pitch numbers.

just a for instance....

in a kawi 750sx, a skat standard 9/17 works well. if you go with a solas, concord, you use an 11/16. if you go with a hooker, or skat mag hub swirl, they hook up much better, and would probably want a 8/16 in the same application.

hope this makes sense.

i think youre on the right track. now do that for all of the skis. haha.

 

[Tyler Zane]

Could someone give me the quick "props for dummies" explanation of what each of the numbers represents. and maybe a tad of info one the hooker, mag, mag swirl.....
thanks, been trying to understand this stuff

The number represents how far the prop would travel in one rotation, in inches, with zero slip.

 

[dbattersby20]

there are sort of some charts on various websites. im blanking out on where it is, but there's a chart that says "stock" "mod" "limited" and then suggests what prop to use for that set up. the problem is there's so many different set ups. Maybe ill start keeping track of all the suggested props i see.

 

[Joker]

i think youre on the right track. now do that for all of the skis. haha.

X2 lol. A nice big book of props would be nice

 

[JamesG]

there are sort of some charts on various websites. im blanking out on where it is, but there's a chart that says "stock" "mod" "limited" and then suggests what prop to use for that set up. the problem is there's so many different set ups. Maybe ill start keeping track of all the suggested props i see.

http://www.solas.com/newweb/pwcproduct/search/default.asp

 

[motoman96]

The number represents how far the prop would travel in one rotation, in inches, with zero slip.

Wrong! Were not talking about boat impellers. The #'s are the degrees of pitch in the prop. How can you say a 9/16 is going to move you? What's it gonna go, between 9 and 16" per rotation? Right.... So at 8k rpm I should be airborn if I listen to your theory. Do not listen or try to comprehend anything I quoted, it'll just confuse those who don't understand impellers ten times more.

 

[motoman96]

Impellers and a guide is impossible to do. To many different scenarios as far as setup, hull, weight, ignition, size of pump etc. Basically the lower the pitch, the easier for the motor to turn, steeper the pitch puts more load on the engine. A strait 15* impeller is trying to turn a given amount of water by each blade in the pump, with it being only 15* the engine can still power thru that no problem. You put the same engine setup in a scenario with a 20* impeller, still trying to push the same amount of water on each blade, but at a much steeper angle, and the motor can't power thru the drag of the higher pitch. So people can make recommendations as to what to try, but can't say for sure. A good engine builder should be able to know your setup and get you pretty friggen close, but a bunch of people on a forum saying to run this size isn't gonna cut it.

 

[Joker]

Impellers and a guide is impossible to do. To many different scenarios as far as setup, hull, weight, ignition, size of pump etc. Basically the lower the pitch, the easier for the motor to turn, steeper the pitch puts more load on the engine. A strait 15* impeller is trying to turn a given amount of water by each blade in the pump, with it being only 15* the engine can still power thru that no problem. You put the same engine setup in a scenario with a 20* impeller, still trying to push the same amount of water on each blade, but at a much steeper angle, and the motor can't power thru the drag of the higher pitch. So people can make recommendations as to what to try, but can't say for sure. A good engine builder should be able to know your setup and get you pretty friggen close, but a bunch of people on a forum saying to run this size isn't gonna cut it.

Ya but there are a handful of guys on here that could tell you

 

[227]

I am certainly no expert, but this is what I've learned over the years. Like already mentioned, there are way too many variables to make a chart. Double number rated props (i.e. 13/17) refer to variable pitched impellers while a single number rated prop (i.e. 15) is simply a straight pitch impeller. Single number props are more obsolete as they only worked at their optimum performance at only one rpm range, while the newer variable props perform better through the whole rpm range, hence most props nowadays are double number rated. The first number refers the low or bottom end angle which effects the skis bottom end performance. The second number is the top angle and effects the skis top end performance. IN GENERAL, the lower the pitch, the ski will hit harder on the bottom and suffer on top end while a higher pitch impellor will do the opposite. So for example a 9/15 would be a mostly bottom end prop that would be used by a FLATWATER freestyler or a small wave surf rider. An 11/17 or a 13/18 would be best for a general flat-water free rider or a larger wave surf rider and a 16/21 would be something a racer or buoy chaser would use. I believe (But am not positive) that a stock pitch prop in an OEM ski is around 13/18 to 14/19 which is a pretty good all around pitch.

 

[NorCalSJ]

I have a hooker 9/15 it rips on bottom and top lol especially if i tune my bpipe for topend it goes!!!

 

[zeski25]

Find a reputable builder and order the prop from them, saves you time, money, and energy. There are too many variables to comprehend unless you're a full time builder/tuner. Pitches/brands are something that are learned by trial and error not read.

 

[Pablo]

Couldnt this information be included with either the carb database or something like the Dasa setup thread. We could have it setup in groupings for surf, flatwater, freeride...

Hull brand, mods to hull...maybe overall weight
Engine specs...carbs, compression, ignition, pipe
Pump size, prop, nozzle diameter, intake grate

Not only useful for similar setups among similar builds or as a guide for newbs.

 

[GTLaser]

Couldnt this information be included with either the carb database or something like the Dasa setup thread. We could have it setup in groupings for surf, flatwater, freeride...

Hull brand, mods to hull...maybe overall weight
Engine specs...carbs, compression, ignition, pipe
Pump size, prop, nozzle diameter, intake grate

Not only useful for similar setups among similar builds or as a guide for newbs.

This all would be good information as I just got into a Blaster and have no clue how to pitch it without a tach.... on my couch I can base my leading and trailing edge by the mods/power and go from there with my pitching tools and tach. With the Blaster I wouldn't want to start from no where without a good guide.