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  1. #1
    '02GPRider's Avatar
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    Dynafly Suggestion

    I'm finally going to make the move to the '05 pump. Currently, I'm spinning a Concord 15/23 @ 7150-7240 RPM, depending on the conditions. What pitch would you recommend for the Dynafly?


  2. #2
    Dan, On the lowell motors weve been bending the DF's anywhere between 14/24 to 15/25 on average. Some less some more. Being your at slight elevation Id lean toward the light side at first, get some rpm readings and then you can adjust accordingly.

  3. #3
    '02GPRider's Avatar
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    Of course, I respect Carl's opinion. But, I'd like to get a better picture of how the pitch correlates from one pump to another. Can you guys give me a plus or minus figure without giving away your pitch? I'm not trying to steal any secrets, here.

  4. #4
    '02GPRider's Avatar
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    It's amazing how you a lot of you knowledgable guys have time to bicker, but can't actually post anything informative. I asked a valid question here and only heard from Carl. That's what is wrong with this forum. Nobody is willing to share any info unless you're in with a certain click.
    Last edited by '02GPRider; 02-17-2007 at 06:20 PM.

  5. #5
    Happily Self-Employed WFO's Avatar
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    I totally missed this thread, and have been sick the last few days, but I am not much of a prop guy anyways. Also I have no experience with tuning for altitude, and I dont have much use for carbs either.

    I think Carl answered the question properly. For questions like yours, I personally would seek out the info I needed, whether it be searching the forums, looking at Phillips speed chart for ideas, or calling tuners and/or guys that specialize in props when asking for prop recomendations.

    I really dont think it has anything to do with "clicks", but I could be wrong. I will usually go outa my way to help... but thats me.

    Oh and I did a little search, and the most common prop for your mods was a DF 14/24 with an 85mm nozzle.

  6. #6
    philip_gpr's Avatar
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    simply take Carl's suggestion and pitch higher. I don't know how the 2 different pumps relate. But a higher pitch will get you more speed. Get your rpms down lower and go faster.

    so maybe try 14.5/24.5

    I would have said use the 87 mm with no siphon tube (though I know a lot of people use the 85, on my ski which is very similar to yours I saw no difference in top speed between the 85 and 87)
    Last edited by philip_gpr; 02-17-2007 at 12:33 PM.

  7. #7
    Duke's Avatar
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    Your portsmith will know the target rpm you need to be at for you desired application. Example, dragracing, topspeed runs, pulling 7 innertubes etc..

    After getting that desired rpm that should be your new goal. Do some searches and find out what pitches achieve that with your setup.

    Someone can now try to get you close. Carl is very good at it and so are a few others but most of us do it ourself because it usually takes 3 to 4 times to get it right.

    My suggestion would be to get a pitch gauge and a file and learn how to do it yourself. There are tips on how to do this in the facts section. When you pitch up the outside diameter gets bigger and will no longer fit in the wear ring.

    Also you will probably get better results if you just bring your post back to the top by posting ttt. Alot of us work all day without internet access.

  8. #8
    '02GPRider's Avatar
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    Thanks, WFO, I've looked around for prop references, too. Because many guys are at or near Sea Level, it's difficult to know if a 14/24 would be right for me. I was hoping a couple of real-world examples from people who switched pumps without switching power would help nail down the difference in pitch from one pump to another, not necessarily the actual pitch.

    Carl suggested that I start with a 14/23, stating that it's much easier to pitch up on the Dynafly than down. I will probably start there. I will also have both nozzles to work with.

    Philip, I see that you are spinning a 15/25 to 7060. What temp was that at? I believe you're at a similar elevation.

    Duke, that's a good idea. But, not for me. I'd be afraid to mess up an expensive prop. I'll let Carl do the tweaking.
    Last edited by '02GPRider; 02-17-2007 at 06:33 PM.

  9. #9
    Happily Self-Employed WFO's Avatar
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    If it helps any, my non-ported set-up was spinning a DF14/23 @ 7150-7180 mid 77 mph.

    IMO go with Carl's recomendation, and you can pitch up if you need more.

  10. #10
    mtrager's Avatar
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    Gp Rider,

    I have a 14/23 that has gone 79.0 Its a great place to start.

    I would keep it at 14 untill you spin it on bottom . I do not spin it.

    You sure are going fast for having an old pump.

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