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Thread: Help from the experts, or the one's runnin them

  1. #16
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    Update on the 28ZX confirmed Scorpion

    He is presently serving in Iraq. He is from Northwest Indiana and we are swapping emails on why he has only seen 74 gps. Sounds like his next boating will be done in the spring.

    Maybe we will have 3 28 ZX Scorpions @ AOTH..

    Welcome to the board Tim and stay safe!
    2000 28ZX Scorpion SOLD
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  2. #17
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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.

  3. #18
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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.

  4. #19
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    Hey there how did you make out with this

    I own a 28zx with 377 stock with headers turning the props inward with 27 mirage labs at 5100 82 mph on gps . Question Im interested in trying some bravo's 4 blade I m guessing 26 pitch anyone try these and do you think I would gain or loose anything


    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

  5. #20
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    great article love those SBC

    I would love to chat with you if you could get back to me. New on here just bought a 28' Scorpion zx with 27 mirages labbed . I am experiencing the same issues at around 76 to 80 with chine my props spin in . Any suggestions on if the 4 blade bravos would work and how fast do you think I would go with 4 blades . Does the boat handle better spinning out and how much speed would I sacrifice. What I m looking for is max speed with safe ride . I would be happy if I could maintain 80 with stability . Any way of finding out or suggestions on where to find out if any combination works better than the current one I have. Thanks


    Quote Originally Posted by Trueser View Post
    Wow I missed this one.

    So far I have hit 79.5 on GPS. One of these days when I donít have my wife on board I will break the 80 MPH. The rev limiters are set @ 5200-5250. I'm running the 25 mirage plus. Tedís old boat that is owned by my friend hit 82-84 on GPS. The boat really loves trim above 7 on the indicator. But it also loves to chine walk. I have a pair of 26 Plus but have not tried them yet. The other problem I hate is getting on plane in ruff water. The props blow out way too easy. I just hit 300 hours and they are still running strong. Griz hit the nail on the head. I would rather have the handling than the speed. The 4 blades I tried got on plane in a heart beat. I could stay on plane @ 1500 RPM. But my top speed was only 71mph. I can always throw the three blades on too whoop Roadtrip. I would also like to swap the props around and see the difference in speed, handling and getting on plane in choppy water.

    The other thing that has limited my speed is my busted up hand. It's finally getting to a point where I can trust it to hold the steering wheel.

    I destroyed a pair of Checkmate's with big block twins. After 10 miles of running we finally stopped and I had to lift my hatch to show that I only had small block Scorpion stock motors. And one of the guys was really pissed that he burned up all his fuel.

    Go easy on the Scorpion comments.

    PM me and we can talk. I have a few questions on Bravo 1's

    Where and when did you get this?

  6. #21
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    Quote Originally Posted by donzi28zxscorpion View Post
    I own a 28zx with 377 stock with headers turning the props inward with 27 mirage labs at 5100 82 mph on gps . Question Im interested in trying some bravo's 4 blade I m guessing 26 pitch anyone try these and do you think I would gain or loose anything
    I run 26" Bravo 1's on mine, but it is a regular 6.2 boat so I'm short a few HP.

    They run great for cruising, handling, planing. But,they aren't good for top end. The boat is super easy to drive with them on and they are super efficient cruising. I think if you did want to try Bravo's I'm not sure if you would need 26" or 28". If we ever meet at a Donzi run we can swap props for a bit so you can try mine out.

  7. #22
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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.
    U.S.C.G. Master Captain
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  8. #23
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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.

  9. #24
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    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 W's. I have a set of 3bl 25p lab mirage boat runs 72 gps 5000 rpm.
    Also have a set of bl 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
    There is an equation for figuring final mph to rpm. I have done it. It requires( calculating rpm to actual turns of the prop "rpm /ratio") X (the pitch =inches per minute)X (60 "converted into inches per hour") / (12" = feet per hour) / ( 5,280 by feet per mile or feet per nautical mile 6,076 )

    so let's see (5000/1.5)=3333 X 26"=86666 x 60= 5200000 /12=433333/5280= 82mph with no slip, 74 with 10 percent slip

    Or 71.3 Knots no slip

    Sounds like you already used a prop calculator Did you factor the slip?

    I notice that there is no change in rpm from either prop. I think your under propped. My guess would be the final RPM is hitting the rev limiter from prop slip . Not the prop topped out ,You want to see a slight drop in rpm when adding more pitch. This is also why it gets blow out getting on plane. Stepped hulls are sensitive to drive trim .In a classic you would start out negative and trim up as it gets on plane. But as I have heard and seen people being ejected with negative trim in stepped hulls. I could not recommend that with confidence.

    With all that said I would say you need to factor the slip ratio in when choosing the the pitch. With both motors peeked out at 5000 rpm and 10 percent slip. I think you have loads of room for more pitch. Your best bet is to try more blade or more pitch. I don't really see anything that your doing wrong, other than" possibly to much positive trim". it is kind of in the allowable, variable the prop can slip.
    machinist ,bore it deeper,ream it bigger, and lap it to a fine finish



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  10. #25
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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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  11. #26
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    Quote Originally Posted by Mr X View Post
    Lol, there were a couple that would not break 80.....but almost all did.
    I looked at a ZXO scorp up in GA and it was a legit low 70's boat (like, under 75 for sure).

    something about the open bow? The advertised weights put the ZXO at 50 pounds lighter than the regular ZX so I don't imagine it's weight. Maybe the engines were built on a Monday.

  12. #27
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    Quote Originally Posted by VetteLT193 View Post
    I looked at a ZXO scorp up in GA and it was a legit low 70's boat (like, under 75 for sure).
    something about the open bow? The advertised weights put the ZXO at 50 pounds lighter than the regular ZX so I don't imagine it's weight. Maybe the engines were built on a Monday.
    Yes, thats exactly correct. Not as aerodynamic.....so as a result, not as fast.
    74 was the best I ever was able to get out of the ZXO Scorpion.
    U.S.C.G. Master Captain
    "Pioneer of insane speed concepts & creations"

  13. #28
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    Quote Originally Posted by Mr X View Post
    Yes, thats exactly correct. Not as aerodynamic.....so as a result, not as fast.
    74 was the best I ever was able to get out of the ZXO Scorpion.
    Thanks, that is great info !!!

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