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Old 03-15-2012, 05:53 AM   #15
Dave R
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Quote:
Originally Posted by MAXUM View Post
That's kind of an odd gear ratio, both of mine had/have 1:1.81

Maybe they change it depending on what engine it's mated with although my first boat had the 3.0L 4 banger and my current boat has the 4.3L V6.

Another thing, changing the speed of the impeller itself can only do so much, you can't pump any more water through the block once you hit critical mass, after that you'd be building positive pressure in the impeller housing.
They use different gear ratios and different props for different boat/engine combinations. They range from 1.32 to 2.40. I'm guessing the 2.4 is popular with non-planing hulls like houseboats equipped with twin 3.0s. The 1.32 would work well on a small and light boat with high HP, like a Donzi Sweet 16 equipped with a 350 MAG.
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