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CLAMP ON'S RULE

I lost my 106mph

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My 91 pro comp used to run 106mph at 7600 rpm with a 2.4, 14.5 x 29 omc srx prop, 2 to 1 gears in a cle 2 hole gearcase. Basically a stock motor. Just an aluminum flywheel and some different reeds. The locknut backed out at a 100mph and destroyed the gears and case. Now it's got 187 to 1 gears back in it. The boat now runs 99.8 at 7200rpm. What do you think? 2 to 1's or play with props? I really hate to tear back into a good case. Another thing is now I have a 4 hole on it. It has 22lbs of water pressure atb 99mph. Is that to much?

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Hmm, doing the math, you'd have to have less than 0% slip at that RPM with the 2:1 case to get to 106mph.  Was that GPS speed or speedo speed?

With a 5% slip, your new numbers seem very feasible.  I run a 1.87 geared BP at 7100 and got 97.5mph with my PCS.

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I'm not sure if 6% is feasable, your pitch may not be accurate.  I'm not sure if i'm correct and please inform me if i'm wrong just never heard of 6%

good luck

Craig

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Just turned 108gps yesterday morning with a 26p yamaha drag copy. 1.87 gears. 8700rpms on a 96 euro. Using the prop calculater with 6% slip the mph turned out to be 107.7 on the calculater. Its possible

                                 Kurt

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