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Discussion Starter · #1 ·
I have about 900 hp 496 bbc, 17'10" graph with a 2 inch runner bottom. It currently has 15% gears with a 11 1/4 - 15 prop. What would happen if I went to 12% gears with a 11 3/8 - 16 prop?
 

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Village Idiot
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That is a great question and I do not have an answer. There are a thousand variables when it comes to props. A prop guys would be good to talk to. Get him what you have and talk to him about what you want to do.

Paul
 

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I have about 900 hp 496 bbc, 17'10" graph with a 2 inch runner bottom. It currently has 15% gears with a 11 1/4 - 15 prop. What would happen if I went to 12% gears with a 11 3/8 - 16 prop?
What you need to do is run your boat with what you have and get a good reading on your speed at a given RPM, say 5000, or 6000 rpm then with this information you can calculate the slippage with this info you will know how good your prop is on this boat 15% is ok 10% is grate. You can try the other prop and compare the to. Then when you get a good prop you can gear to that prop. With that much HP you should run a 18 to 25 % gear.
 

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JJ, great post! It made me think of a few things, what RPM does it make that power at? 6500 or 8500? That plays into gearing in a big way! As JJ said, figure out what you have first. You never know, the boat may like the new prop even with the same gears. It may drive better with the new gears and the current prop.

Test, Test, and then test some more. And then when you are done, test a few more things just to make sure. The guys that are really fast have got that speed from trying everything and figuring out what that combo really wants, not just what us internet jockeys tell them.

Paul
 

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I have about 900 hp 496 bbc, 17'10" graph with a 2 inch runner bottom. It currently has 15% gears with a 11 1/4 - 15 prop. What would happen if I went to 12% gears with a 11 3/8 - 16 prop?
You need a 18% min. probably be best with a 22%-26% gear if you really have a 900hp motor
 

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Discussion Starter · #6 ·
I have about 900 hp 496 bbc, 17'10" graph with a 2 inch runner bottom. It currently has 15% gears with a 11 1/4 - 15 prop. What would happen if I went to 12% gears with a 11 3/8 - 16 prop?
Thanks for all your input guys. I just screwed up my prop shaft trying to get prop off. Anyone know where I can buy a new one ?
 

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