prop is too much work for engine change diam/pitch

Discussion in 'Props' started by gttdnbman, Oct 11, 2009.

  1. gttdnbman
    Joined: Aug 2009
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    Location: michigan

    gttdnbman Junior Member

    I have a twin screw 220 hp engines and a 1-1 ratio with 15x12 federal 3 blade props boat goes good but i can tell that top end just isn't there engines seem to be working to hard should I drop my diam or pitch and how much?
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    What kind of engines and what is your top RPMs
     
  3. gttdnbman
    Joined: Aug 2009
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    gttdnbman Junior Member

    v6 5000 rpm
     
  4. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I assume it is a 4.3 gas engine. The max RPM should be 4300 to 4800. You need more diameter or more pitch. Two inches of pitch should lower the RPM aobut 300 to 4700.
     

  5. Frosty

    Frosty Previous Member

    Well that will make them work harder. I think he meant rev too hard perhaps?

    Mr gtt increasing pitch or diam is like going up a gear, so it will work harder in HP terms but will rev less,--like changing gear on a car --the RPM's come down.

    Its possible you wont see much if any increase in speed.

    Do you normally drive full power all the time?
     
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