32 to 34 Prop?
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32 to 34 Prop?

  1. #1
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    Default 32 to 34 Prop?

    Guys

    I have a 25'7 Effect.....a 502 Whipple BBC that throws off 900 HP on the dyno...I am running a 32 P prop and at 5,000 RPM I am in the low 90's. I have the XR Brovo Drive with 1:50 gears

    Question: Can the boat and engine pull a 34 P prop to get more MPH? What are the pros and cons of running the 34 vs the 32?

    Thanks

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    Quote Originally Posted by Zzyzzx View Post
    Guys

    I have a 25'7 Effect.....a 502 Whipple BBC that throws off 900 HP on the dyno...I am running a 32 P prop and at 5,000 RPM I am in the low 90's. I have the XR Brovo Drive with 1:50 gears

    Question: Can the boat and engine pull a 34 P prop to get more MPH? What are the pros and cons of running the 34 vs the 32?

    Thanks
    What rpm's can they motor turn?
    Don't sweat the "Petty", Pet the Sweaty!

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    The rev limiter is set at 6k

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    Quote Originally Posted by Zzyzzx View Post
    Guys

    I have a 25'7 Effect.....a 502 Whipple BBC that throws off 900 HP on the dyno...I am running a 32 P prop and at 5,000 RPM I am in the low 90's. I have the XR Brovo Drive with 1:50 gears

    Question: Can the boat and engine pull a 34 P prop to get more MPH? What are the pros and cons of running the 34 vs the 32?

    Thanks
    I HAD almost the same setup-stock 502/[email protected] prop, 5400rpm-96mph
    I heard the 34p props are a different animal, and to stay away from them- also means
    more strain on the drive- what exactly are you trying to achieve?


    Out With The Old, In With The New.......Goodbye Blinding Acceleration, Hello Sustained High Speed (in comfort)

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    Senior Member Familycat's Avatar
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    Wouldn't taller gears in the drive be a better choice?
    "Equity at its Best"

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    mud slinger plaster dave's Avatar
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    I say you need to go down in prop till you reach 6k on the tach.
    Don't sweat the "Petty", Pet the Sweaty!

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    Like the most of you, I am looking for a little more speed....you see/hear all the time set-ups with 1/3 less HP than I have and you will hear numbers in the 90 MPH range....I was simply thinking I could put 2 more pitch (to the 34P) and see the mid or upper 90's MPH. I am running 5 lbs of boost on a GT Performance build....not looking to go ape-shit, just want near the 100 MPH benchmark

    I guess I should toss the wifey, kids, all their chit and see what I get

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    mud slinger plaster dave's Avatar
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    Quote Originally Posted by Zzyzzx View Post
    Like the most of you, I am looking for a little more speed....you see/hear all the time set-ups with 1/3 less HP than I have and you will hear numbers in the 90 MPH range....I was simply thinking I could put 2 more pitch (to the 34P) and see the mid or upper 90's MPH. I am running 5 lbs of boost on a GT Performance build....not looking to go ape-shit, just want near the 100 MPH benchmark

    I guess I should toss the wifey, kids, all their chit and see what I get
    You have to big of a prop on it if you cant hit the rev limiter.
    Don't sweat the "Petty", Pet the Sweaty!

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    Quote Originally Posted by plaster dave View Post
    You have to big of a prop on it if you cant hit the rev limiter.
    X2- I'm wanting to try a 30p on mine, for this very reason


    Out With The Old, In With The New.......Goodbye Blinding Acceleration, Hello Sustained High Speed (in comfort)

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    Quote Originally Posted by Familycat View Post
    Wouldn't taller gears in the drive be a better choice?
    good idea, but not very budget friendly for most


    Out With The Old, In With The New.......Goodbye Blinding Acceleration, Hello Sustained High Speed (in comfort)

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    Prop down until you are at the rev limiter if you want more speed. Maybe try a five blade if you can get a loaner. You should easily hit 100 with that much HP and that hull. Good luck. I think you will go slower with a bigger prop.

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    Put a 28p Bravo 1 on that thing. You need more rpm.

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    Comment:

    Well with a 1.50 gear ratio and 900+/- HP you should easily pull this propeller. You probably hit the rev limiter pretty quick.

    In fact at a liberal 18% slip ratio you should be right at 99MPH with this propeller.

    Some of the LIMITED information your providing is not the proper manner for obtaining top speed.

    I do not recommend having people in the boat when your propeller testing. Second, you need to have the boat at WOT and trimmed for speed versus cruising. Typically a hull like yours likes a little chop on the water and into the wind should get you the best top speed.

    Good luck!

    KAP
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    www.dougwrightwest.com Home of X-treme Outboards

  16. #14
    Senior Member Hullshot's Avatar
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    there seems to be a lot of issues here with prop, drive height and RPM's. You should prop the boat to hit max RPM's or at least very close to it. Talk to Robbie Racer about the 257 Carerra. he has done everything to his to obtain the speed he is going. The motor is loaded way heavy now and you need to get it to perform. You are only using about 700-750 HP of your 900Hp that you say it has at 5000 rpm's.

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