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Thread: Alpha Drive HELP

  1. #1
    Havasuhog
    Alpha Gear Ratio Help
    I have a 92 Ultra 350 mag/alpha Gen 2 - 1.5 ratio with a High Five 21p SS prop. I bought a brand new alpha Gen2 - but it has a 1.81
    ratio. The question I have is
    a) Should I re-gear it to a 1.5 (Is the 1.5 stronger)
    b) If I stayed with the 1.81 - Could I just just change to a 23p High Five with about the same results (MPH and WOT RPM)
    c) I'm confused - I think I need another beer!
    Please Help
    Thanks

  2. #2
    Bling Bling
    Originally posted by Havasuhog
    Alpha Gear Ratio Help
    I have a 92 Ultra 350 mag/alpha Gen 2 - 1.5 ratio with a High Five 21p SS prop. I bought a brand new alpha Gen2 - but it has a 1.81
    ratio. The question I have is
    a) Should I re-gear it to a 1.5 (Is the 1.5 stronger)
    b) If I stayed with the 1.81 - Could I just just change to a 23p High Five with about the same results (MPH and WOT RPM)
    c) I'm confused - I think I need another beer!
    Please Help
    Thanks I would have to say a new prop would be less expensive then a gear change, plus, ask the person you bought the drive from and see if there warranty will stand with the gear change. About the prop pitch, call Brian at valley propeller 805-644-5055 he can not only make you a good deal on a new prop, but figure out what pitch you really need. If all else fails, chase that beer with a double shot of grey goose, orange is best.

  3. #3
    5th Horseman
    I'll take a shot at it,
    A) Regearing is up to you in the end, 1.8 might be stronger
    B) 25 pitch would be closer with the 1.8 compared to the 21 at 1.5
    C) have another beer
    The 1.8 is intended for large slow boats. It's knda like the axle ratio in your car, the lower the ratio, the slower you'll go at the same RPM. Big trucks use ratios like 5.13 so they can get the load moving, high speed car would use 2.73. Large boat, 1.8, small fast boat, 1.5, even faster boat, 1.36. Like Mr. Bling said, cheaper to reprop if your stuck with that ratio.
    Paul
    .

  4. #4
    Havasuhog
    Thanks!
    I found another prop calculator from BAM marine in florida
    Here's the link
    http://www.go-fast.com/bam_marine_knowledge_base.htm
    I'm thinkin my motor would'nt have enough torque to spin a 25" pitch and still maintain MPH even though the 1.81 Ratio and 25 pitch match the table for WOT RPM. What I don't see in the calculations is the effects of low end torgue that would be needed
    to turn the prop. (Im probably wrong!)
    The 1.5 gears are fairly cheap. I'll call some prop shops and see what their opinon is.
    Next Boat - Conquest / Viper V-10 motor / Saro drive.
    It's easily to Dream

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