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  1. #1
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    Help from the experts, or the one's runnin them

    Fellas new here, looking for some knowledge from those who know Props, and step hulls. I am going to add a link to Q&A Posted on OSO. I could really use some conformation or other advice. Appreciate all the help.

    2000 ZX with the 377's. I have a set of 3bl 25p lab mirage boat runs 72 gps 5000 rpm.
    Also have a set of 4bl 26p lab Bravo I 74 gps 5000 rpm.

    What am I doing wrong? Thought this should be an 82 mph boat with the twin step hull? Fuel levels were approx half. 1-4 persons did not matter.

    2nd question. I have been getting a lot of cavitation when getting to plane. I have backed up on the K planes and has since helped. Thanks for any and all help.


    http://www.offshoreonly.com/forums/s...d.php?t=194036

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    are you using non-ethanol, premium fuel?
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    Let me say this first. That boat won't run 82 with stock Scorpion power And I don't care if Don himself says it will, It is too big!!! I personally think if you have to run a labbed prop to get that extra 1 to 3 mph your wasting money. I believe Trueser Tried some other props at Cumberland that handled better. Since I sell and test props as most know, I can tell you this. You need to try other props. Every labbing guy will tell you his are the best. I have an 86 mph 22 and can say that the only labbed props I have on my boat were labbed Merc racing and two Throttle up props( not their CNC ) and my stock out of the box Precision props were at least 2 MPH faster. I don't labb props and won't, It isn't worth it to me. Ask Trueser for his opinion, He isn't capable of lying about his boat. He likes me and will tell me to stick it if he doesn't believe me. One thing there is more to a boat then just speed, It id called Handling.
    Randy owner of Donzis since 1966
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    Big Grizz nailed it.

    These boats are all about handling.

    I would take a perfect handling 65 mph boat over a 70 mph skittish boat any day.

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    Boat does 80+ I own one . GPS

    Mine does 80+



    Quote Originally Posted by biggrizzly View Post
    let me say this first. That boat won't run 82 with stock scorpion power and i don't care if don himself says it will, it is too big!!! I personally think if you have to run a labbed prop to get that extra 1 to 3 mph your wasting money. I believe trueser tried some other props at cumberland that handled better. Since i sell and test props as most know, i can tell you this. You need to try other props. Every labbing guy will tell you his are the best. I have an 86 mph 22 and can say that the only labbed props i have on my boat were labbed merc racing and two throttle up props( not their cnc ) and my stock out of the box precision props were at least 2 mph faster. I don't labb props and won't, it isn't worth it to me. Ask trueser for his opinion, he isn't capable of lying about his boat. He likes me and will tell me to stick it if he doesn't believe me. One thing there is more to a boat then just speed, it id called handling.

  6. #6
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    Quote Originally Posted by donzi28zxscorpion View Post
    Mine does 80+
    Yes, mine did it all day long. Sometimes 3-4 over.
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    Quote Originally Posted by Mr X View Post
    Yes, mine did it all day long. Sometimes 3-4 over.

    That is really funny considering your background. When I mentioned that to the guys currently at Donzi they laughed and said a stock 28 ZX scorp would never run over 80. They really don't know the ZX line very well anymore at the factory it seems.

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    Quote Originally Posted by VetteLT193 View Post
    That is really funny considering your background. When I mentioned that to the guys currently at Donzi they laughed and said a stock 28 ZX scorp would never run over 80. They really don't know the ZX line very well anymore at the factory it seems.
    Lol, there were a couple that would not break 80.....but almost all did.
    U.S.C.G. Master Captain
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  9. #9
    mrfixxall Guest

    mrfixxall

    Quote Originally Posted by IUHalls View Post
    Fellas new here, looking for some knowledge from those who know Props, and step hulls. I am going to add a link to Q&A Posted on OSO. I could really use some conformation or other advice. Appreciate all the help.

    2000 ZX with the 377's. I have a set of 3bl 25p lab mirage boat runs 72 gps 5000 rpm.
    Also have a set of 4bl 26p lab Bravo I 74 gps 5000 rpm.

    What am I doing wrong? Thought this should be an 82 mph boat with the twin step hull? Fuel levels were approx half. 1-4 persons did not matter.

    2nd question. I have been getting a lot of cavitation when getting to plane. I have backed up on the K planes and has since helped. Thanks for any and all help.


    http://www.offshoreonly.com/forums/s...d.php?t=194036
    which way are your props spinning? in or out?

  10. #10
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    Your numbers are correct for those pitches based on 10% slip. You might be able to get 1 or 2 MPH more out of a different set of props and some more seat time but the speeds you are seeing are consistent with the pitch and props you are running.

    I don't know what the rev limiter is on the 377's but I suspect they are right around 5000. It's possible you are hitting the limiter and have some more speed with some bigger props, especially since both sets of props, a 3 blade 25P and a 4 blade 26P both turn 5000 rpm. If you have Faria gauges it's entirely possible the tach is as much as 400 RPM off on the high side.

    To do 82 mph you will need to be able to spin a 29P or 30P prop to the indicated 5000 RPM's assuming you have the 1.5:1 ratio drive (which it looks like from your slip numbers).

    Try some bigger props.
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    I talked to Trueuser. He said with some seat time he was able to get high 70's so far. Maybe he will chime in.

    Mr. X also knows this boat well. I think he broke the 80 mark in his. I seem to remember he did the SM exhaust on his scorps.
    2001 35 Fountain Lightning w500 EFI's
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    If it helps the way you feel about the boat you are not alone in your problem with the scorpian not living up to the numbers that Donzi published to market the boat, not surprising considering the boating industry inflates the numbers to sell boats or best the other manufacturer. I have only read about one scorpion running 80 plus on stock power, It was Mr X and his with some exhaust upgrades. As for yours.....well it is a bit slow for a scorpion but in the range to be considered normal....Best you will see is high 70's under ideal conditions. Hate to say it but thats the way it is. You may be able to pick up a bit with some better props but ther is no magic bullet that will give you 8-10 mph to make it to 82 with the current set up and power.
    Now if you want to get srious about it I can point you in the direction of a guy with a pair of procharged small blocks and a bunch of other things, extension boxes and big tabs that runs to 95 with authority and will peel your eyebrows back....all in a 2000 28 ZX, boat hails out of New Orleans.
    Tex
    97 27 zx twin step yep it is the slow boat
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    Tex

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    Quote Originally Posted by The Hedgehog View Post
    I talked to Trueuser. He said with some seat time he was able to get high 70's so far. Maybe he will chime in.
    Mr. X also knows this boat well. I think he broke the 80 mark in his. I seem to remember he did the SM exhaust on his scorps.
    What happened with his motors?
    97 27 zx twin step yep it is the slow boat
    500 EFI .........................with a little Boost and
    a little more boost
    48' Pacemaker Tournament Sportfish twin Detroits

    Yeah... I was.... Kind of a Big Deal.....

    Tex

  14. #14
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    Nice to see someone nows what there talking about

    I agree since I own one that does 80+ at 5100 with lab 27 mirages


    Quote Originally Posted by The Hedgehog View Post
    I talked to Trueuser. He said with some seat time he was able to get high 70's so far. Maybe he will chime in.

    Mr. X also knows this boat well. I think he broke the 80 mark in his. I seem to remember he did the SM exhaust on his scorps.

  15. #15
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    Quote Originally Posted by mrfixxall View Post
    which way are your props spinning? in or out?

    Inward... To answer a few other questions it handles really well, I was dealing with a little chime walk at the higher speeds, but I got that worked out and as for handling the waves I was out in 5-7's (not Swells) and was running 65. I am interested in any small tweaks you are using. All Freshwater it might be 380hrs on motors. Thanks for the help.

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