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Thread: Propeller Question

  1. #1
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    Propeller Question

    Hey All,

    Quick question looking for your opinions. I have an 18 classic with a 300hp 350 Chevy bolted to a gen 2 alpha. Currently there is a 3 blade 14x24 pitch stainless wheel on the boat and it only turns 4000 id like to get the boat to turn around 5000 what should I get for a propeller? I was thinking a 14 1/2 x 21 would get the job done as well as give me ample bow lift but not sure what do get mirage, Yamaha etc etc? What are your opinion's, I'm sure this question has been asked a million times on here so sorry if that's the case.

    Thank you!

  2. #2
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    21p sounds about right

    2" of pitch is normal worth 300-400rpm but your engine is overloaded if she's only getting to 4000.
    You will want to confirm your drive ratio. If it's a 1.3 you'll probably want a 19p, if 1.5 then 21p.
    I ran a 23p Mirage on my 20' Minx with a small block Alpha and at WOT she was about 4600rpm running light with 270HP and 4800rpm with 300HP.
    Both a Merc Mirage and Turbo 1 work well on my 22' Classic.
    Thank you, Patrick
    1994 18' Classic 350Mag Alpha

    Previously owned Donzis -
    1996 22' Classic, 502Mag Bravo
    1987 20' Minx, 350Mag Alpha
    1975 18' Classic, 350Chevy Volvo 280

  3. #3
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    Quote Originally Posted by Pat McPherson View Post
    2" of pitch is normal worth 300-400rpm but your engine is overloaded if she's only getting to 4000.
    You will want to confirm your drive ratio. If it's a 1.3 you'll probably want a 19p, if 1.5 then 21p.
    I ran a 23p Mirage on my 20' Minx with a small block Alpha and at WOT she was about 4600rpm running light with 270HP and 4800rpm with 300HP.
    Both a Merc Mirage and Turbo 1 work well on my 22' Classic.
    I don't think they make a gen 2 Alpha with 1:3 gear set. Bravo's took over that chore .

    I think that the stock prop for an 350 mag is a 21P. My Mirage Carries the bow well and being a three blade, you can get some slip to break them loose
    machinist ,bore it deeper,ream it bigger, and lap it to a fine finish



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  4. #4
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    Quote Originally Posted by joseph m. hahnl View Post
    I don't think they make a gen 2 Alpha with 1:3 gear set. Bravo's took over that chore .

    I think that the stock prop for an 350 mag is a 21P. My Mirage Carries the bow well and being a three blade, you can get some slip to break them loose

    Do you know the diameter of the propeller that you are running?

  5. #5
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    Pretty sure the Mirage is 14 5/8" and the Turbo 1 is 14 1/4".

  6. #6
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    IMO you are right on a 21 3 blade, that should put you at about 46-4700.
    No matter what your beliefs are "GOD BLESS AMERICA"

    Fully retired marine tech near 60 years in the biz.

  7. #7
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    are you trimming it out ? you should be able to turn a mirage plus 23p with that set up .
    better to die on your feet, than live on your knees

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