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  1. #1
    JFizzleJR's Avatar
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    DIGGS, Speedy, Vern, Dan etc.

    What are you guys doing as far as tweaking the prop for your setups? I have the same setup as you guys but am hitting the limiter with a 15/20r with 2 mm added to it. I have the 81mm ring as well. I was going to put the 80 in but it's way too loose in my nozzle. I'll have to drill holes in it first for some set screws.


  2. #2

    prop

    i have an untouched 15/20 with the 81 ring in mine right now.

    the temp here last time i rode was 83 and lake was 83.
    elevation is 820 feet.
    you will probably need an 79 or 80 ring for your temps.

    speedy has the same as me.


    is your prop bent to take away rpm or add?

  3. #3
    JFizzleJR's Avatar
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    I guess I'm not really sure anymore. I could've swore it was 2mm added so it would turn lower rpms. Maybe it's the other way around
    I'll try an out of the box 15/20 tomorrow.

  4. #4

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    Out of the box will work right NOW for our temps. Should see great numbers. (WINK!)

  5. #5

    15/20

    cool let us know James how it does...............trust me if you can stay off the limiter the air is good right now....

  6. #6
    RXP'in in MI's Avatar
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    15/20R and 80 mm nozzle ring

    All the 80 mm rings I have seen (Vern has one as well as I) fit loose in the bored nozzle. What I did was grind (dremel or small hand air grinder) three divots/recesses in the ring where the set screws contact the ring for locking it in place. Without doing this the ring will get pushed back out of the nozzle due to the thrust, the small retaining groove in ring (inadequate in my book) and the loose fitting ring making it difficult to keep the ring in place even when secured w/the set screws. OU812 had posted a thread before about blowing the 80 mm ring right out of the nozzle after a short time of use (loose fitting ring?). And yes I did add a third set screw for ring retention. I left one @ the 3 o'clock mark (0*) and placed the other two 120* apart from the original one left in location. I did this last winter as I did not think two set screws could provide enough holding force and had noticed last year that the ring was getting forced out of the nozzle. The two set screws relocated @ 120* and 240* do not pose a problem for steer nozzle clearance. Note, when tightening the set screws do not overtighten as to collapse the ring and force it into the water's path of exit. Just evenly tighten the three set screws while watching the inside of the nozzle. This is especially critical when putting the loose fitting 80 mm ring in the nozzle.
    I was using an untweaked 15/20R impeller w/a 80mm ring. I recently bent the trailing edges back (towards the pump housing vanes) so I would be able to use a 81 mm ring and have some adjustablity with nozzle rings in cooler spring/fall weather. I bent the trailing edges so they were all @ the same height. Two blades required 0.040" (1 mm) and two required 0.020" (1/2 mm) to get their trailing edges even. I improvised a small layout table and did my measuring on the impeller from the inner hub/mounting surface of the impeller since this orientated the impeller in its true mounting setup. With this tweak it brought my RPMs to 8070-8090 w/the 81 mm ring in upper 70'/low 80's air temps w/mid 70's water temps ... where I wanted to be RPMwise.
    Last edited by RXP'in in MI; 09-28-2007 at 09:26 AM.

  7. #7
    JFizzleJR's Avatar
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    good info, thanks a lot dan

  8. #8
    JFizzleJR's Avatar
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    Lake temp is high 60s, Air is low 60s. 78.0 mph at 8100-8150 w/ 81mm ring. I still need to make the 80mm ring fit and fill the intake grate holes +1 rideplate hole. This is with the out of the box 15/20r. Thanks for the advice guys.

    On a side note, I did see 12.1 psi of boost today. All I have to say is..Damn

  9. #9
    sleeplessnMS's Avatar
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    Remember that all otb 15/20's are not the same

  10. #10
    JFizzleJR's Avatar
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    yeah but mine and theirs are acting pretty much the same

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