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  1. #1
    Vern's Avatar
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    3 blade vs 4 blade on Stage 3?

    I have a 15/20 4 blade and a 15/19 3 blade and am going Riva Stage 3 for next year. I am curious if people have tried both impellers with the Stage 3 ECU setup ... My 3 blade has a little pitch added and was trued up by Carl at Island, but if the 4 blade works well with this setup, I really should send it out for a touch up and truing over this winter, as it has 2+ seasons on it. Anybody try both impellers with their Stage 3 setups?


  2. #2
    Vern

    Use the 3 blade Skat Trak. It will hook up better out of the hole & it is also lighter. This is very important to run a lighter prop when spinning the RPM that a Stage 3 will produce. The 4 blade Solas at high RPM (above 8200+) can lead to vibration, causing problems with the carbon seal & possibly even bigger problems. (because it is heavier) Also, make sure your running the stage 3 reduction nozzle so you can control RPM and hook up etc. by stuffing the pump or less restriction...depending upon its behavior...by changing the reduction rings.

    Have fun....good luck!

  3. #3
    DaveC's Avatar
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    Do you have any more info on the 15/20 and the vibration problem ? I have not had any problems with it, but would like info from those that have. Jerry have you heard of the 15/20 impellers being a problem above 8200 RPM ?









    Quote Originally Posted by bamf View Post
    Vern

    Use the 3 blade Skat Trak. It will hook up better out of the hole & it is also lighter. This is very important to run a lighter prop when spinning the RPM that a Stage 3 will produce. The 4 blade Solas at high RPM (above 8200+) can lead to vibration, causing problems with the carbon seal & possibly even bigger problems. (because it is heavier) Also, make sure your running the stage 3 reduction nozzle so you can control RPM and hook up etc. by stuffing the pump or less restriction...depending upon its behavior...by changing the reduction rings.

    Have fun....good luck!

  4. #4

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    Quote Originally Posted by Vern View Post
    I have a 15/20 4 blade and a 15/19 3 blade and am going Riva Stage 3 for next year. I am curious if people have tried both impellers with the Stage 3 ECU setup ... My 3 blade has a little pitch added and was trued up by Carl at Island, but if the 4 blade works well with this setup, I really should send it out for a touch up and truing over this winter, as it has 2+ seasons on it. Anybody try both impellers with their Stage 3 setups?
    i put a 14/19 on my set up when my 15/19 3 blade broke, and i had more top end, ie 2mph

  5. #5
    sleeplessnMS's Avatar
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    We all use 4 blade. In our tests using pace boats the holeshot wasnt enuff to make up for topend loss with the 3 blade. I've tried it all and a 4 blade is whats in my rxp.. the 3 blade was maybe 1/2 boat on the hit but the 4 blade just drives right on by once on plane good. Both ski were setup for 8560 rpm's.

  6. #6
    HORSEPOWER JUNKIE 9secZO6's Avatar
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    Quote Originally Posted by sleeplessnMS View Post
    We all use 4 blade. In our tests using pace boats the holeshot wasnt enuff to make up for topend loss with the 3 blade. I've tried it all and a 4 blade is whats in my rxp.. the 3 blade was maybe 1/2 boat on the hit but the 4 blade just drives right on by once on plane good. Both ski were setup for 8560 rpm's.
    Well said my confederate brother.....and as far as the weight goes, I would think as long as no imbalance, no issue. I just posted about the 4 blade on the turbo thread........

  7. #7
    Dave Sharp dav_dman's Avatar
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    i would think in a CC race the three blade would end up giving you a nice advantage then.

    For rec riding it looks like the 4 blade would let you pull away from your friend in glass..... but what about chop? Skat is usually a really good chop prop...

  8. #8

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    You can pitch the 3- blade to .5mph of the 4-blade BUT it is a pain in the prop. The water will stall on the blade if you have too much arch in the pitch.

  9. #9
    Vern's Avatar
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    Thanks guys, I appreciate the input. Funny, when Dan and I tested the 3 blade vs 4 blade on our Stage 2+ skis, it seemed similar ... slight advantage to the 3 blade out of the hole, but 4 blade was a little better on top. I was not sure if that carried over to the higher rpm setups too, but it sounds like it does. Dan did like the 'hit' of the 3 blade though and it did seem to have a holeshot advantage ...

    Do most of you run the 15/20 4 blade 'straight up' on the Stg 3 setups, or add or remove a mm or two on the trailing edge (not running a Rude charger, just the standard Stg 3 SC)? Nozzle size? I have 3 nozzles and lots of rings ...

  10. #10
    El Tartaro luismendez25's Avatar
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    I was amazed last week while doing back to back tests with a 15/20 -4 blade and a 15/19-3 blade with a little bit of pitch and at the same rpm's i was getting the same speeds which in prior ocassions i would get more speed with the 4 blade. Any reasons for this?

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