superjet impeller change Question

[Speedlaw]

I've had a 14/18 Skat super slim line prop on my sj since 1999. I'm thinking of a replacement Swirl prop. Impros recommends a 13/16 swirl prop.

The ski is lightly modded. Worx intake grate and ride plate. Primer kit, chokes removed, head lightly milled. The ports have been cleaned and matched but not raised or opened. Stock pipe.

UMI steering and bars.

Most of my riding is rough water, and I'm not too into top speed, since I rarely see flat water.

Anyone compare both ? Most guys on this board have skis tweaked to within an inch of their lives, not my lightly modded ride.

The Skat Trak was the recommended prop in 99....has time marched on ?:Eyecrazy:

thanks

See you next year at the Daytona Freeride !!!

 

[Speedfreak]

I like Dave at impros but if you are looking at low end punch and don't give a hoot about topend I would go one step lower that what he recommended. Even though he was suppose to take that into consideration.

I would suggest getting that prop repitched and save your money for a pipe. That will make more of a difference than any prop. And I had that prop on my ski and when the Concord was the thing I switched and maybe if the comparison was back to back I would have felt a difference but I switched over the winter and couldn't tell a difference.

 

[Mouthfulloflake]

you should go lower than a 13/16 especially if you dont care about top end.

Im running a solas concord 12/15 on a 701 ( 61x) powered boat with a pipe, and it has good bottom end.

I ran a 13/16 it was too tall for my engines power output.

In my opinion, its best to always err on the side of lower pitch, then as you increase your engines power output you can adjust from there.

a too tall impeller will make the boat damnm nearly UN-fun to ride in my opinion.

 

[Mouthfulloflake]

Oh yeah...

I had a slim line 14/18 or 14.5/18.5, EXTREMELY too tall for my set up.

drop down to something 13/16 ( lower even) concord, or 12/17 swirl ( skat) and feel a WORLD of difference in throttle response.

 

[Speedlaw]

I think I'm getting this, but not sure

Thank you for the replies. Since I'm normally the ONLY standup in my area, this board is essential to making me feel like "im NOT all alone out there".

I'm not totally understanding this. the 14/18 prop on my boat is "tall", and I assume that like a higher gear in a car, I get top speed and less torque. The 13/16 or 12/15 is a "lower" gear, with more torque and less top end.

All the highly modded skis I see are running "Lower gear" impellers, so combined with a higher output and peakier motor, you run a lower "gear" to get the ski up on the powerband sooner, correct ? Since most freeride skis are all about 0-30 mph up the side of a wave, top end is not very important, unlike, say a flat water grudge racer on a sit down, where possibly you'd go the "higher gear" to get that top speed, whereas the "off the line" might not be 1st priority.

I ride in the Hudson river, which is normally choppy with 1-4 foot waves. When the wind kicks up, I get these very consistent 4 foot waves, which are perfect "moguls" to jump off, and I'm normally looking for squirt from zero to the next wave. Flat water is quite rare in my world. I also get out into real water (Long Beach Island, NJ) and (Matansans Inlet, FL) a few lucky times a year. (even ridden with a few "names", but that's another story-great thing about this non-sport, is that most folks are cool)

I've left my ski mostly unmodded, as power is adequate for my use, and I'm usually alone out there, so a cranky ski is not a good idea. I do have a marine radio and a membership in a local boat club, so I do have "friends" in case of emergency.

Swirl props didn't exist when I got the 14/18, which appears to be (now) the ideal prop for a waveblaster.

Thanks...any further ideas would be appreciated before I bust loose the 250.00.

 

[Mouthfulloflake]

I think you can get a new skat swirl for under $250, someone on this board was talking about it last year or so.

i would try that, and if you want an even lower 'gear" have it it repitched lower.

one reason modded engines can run the lower gears is that they also turn more RPMS than stock boats.

and since the impeller pitch is basically FIXED, more rpms with a given pitch = more speed.

I think you have it though, and your description of riding sounds much like my own style, I like to be able to just put put up to a wave, and then hammer it in the trough.

 

[IMPROS]

I think you can get a new skat swirl for under $250, someone on this board was talking about it last year or so.

i would try that, and if you want an even lower 'gear" have it it repitched lower.

one reason modded engines can run the lower gears is that they also turn more RPMS than stock boats.

and since the impeller pitch is basically FIXED, more rpms with a given pitch = more speed.

I think you have it though, and your description of riding sounds much like my own style, I like to be able to just put put up to a wave, and then hammer it in the trough.

That's the key. Along with a pipe is typically an enhancer or rpm removal to let the r's go up. I don't remember this call, but I usually don't recommend too low of impeller pitch with the stock ignition, or you'll be beating the rev limiter. Either way, a 13/16 Concord or Freeride Swirl is a better bottom end impeller than the 14/18 SSL that he has.
If you're planning on changing the limiter, then go to a 12/15.
David