Will changing from a 3 prop to a larger 4 prop get better mpg or power?

I have a 1978 26f pacemaker with a 305 crusader engine. I currently have a 13 x 10 prop(3 blades). The 10 means the degree of the angle on the blades if I am not mistaken... Not looking or more speed, just power to get out of the waves and maybe better steering.

3 Answers

  • mark t
    Lv 7
    1 decade ago
    Favorite Answer

    Props are measured by diameter and pitch. In your case its a 13" dia. x 10" pitch. Usually a four blade prop would be used in a more powerful engine and for smoothness. A lower pitch would give you better acceleration but a lower speed for a given rpm and higher pitch would give you more speed and less acceleration (if the engine could pull the load). Instead of investing in a different prop what you could do is have your prop shop put a cup in the blade (its a lip at the end of the blade). You could start off with a moderate cup and go from there. The prop pros will have suggestions.

  • Anonymous
    1 decade ago

    Four blade props usually have better acceleration and a little better handling than three blade props. Props are measured in pitch. If you have a 13 pitch, that means under optimum conditions with no slip, which will never happen, the prop moves forward 13" with each roatation. The other number, 10 in your case usually refers to the diameter of the prop, however 10" diameter would be pretty small for an I/O.

  • 1 decade ago

    4-blade props give better acceleration due to the lower amount of 'slippage' where the water comes off the blades. This because of the way the blades work through the water.

    They are not so good with lower H/P motors, but work well with the rest.

    As for mpg, it always depends on how you use that throttle, and, of course, the power equation comes back to what you have as an engine, with what mods.

  • 1 decade ago

    You have to stay within the manufacturer guidelines for the prop. any more pitch and you cause the motor to have to work too hard, resulting in internal engine problems. The prop won't give you more power, that comes from the motor, it will only give you a faster top end. check into it before you change it.

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