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XR...what ratio to run

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Old 10-23-2007 | 05:15 PM
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Default XR...what ratio to run

I'm getting a new XR drive and was trying to figure out whats the best ratio to run. In my head I was thinking the 1.26 with a small prop will make for a happy long life behind 550 hp. I was running a 26 Bravo prop with a 1.5 Bravo 1 @ 5200. So maybe a 22 or 24 Bravo on a 1.26 XR. What do you think?

It will be on a 26' single engine so planing and acceleration should not be a problem.

Last edited by jdub; 10-23-2007 at 05:23 PM.
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Old 10-23-2007 | 05:54 PM
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I've learned that hulls will react differently to certain pitch/geometry changes. So on the surface it might look like the thing to do, to change the gear ratio and prop, but the boat might not like that pitch of prop. I run a 1.5 with a 26 Bravo (summer, 28B winter) and the boat is very happy with that setup. If I remember right, the 27 Fountains worked best with a 28" Bravo and they came with a 1.65 gearset as do Formulas 292's. You might be good where you're at. If you're not leaving the sticks WFO during launches or planing at WFO, then an XR should be ok with that power. Get some slip numbers and talk to other Corsa owners about their setups would be my recommendation.
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Old 10-23-2007 | 06:25 PM
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I changed from a 1.5 to 1.36 and I gained a few mph on the top. The accelleration dropped off and the boat is more sensitive to weight, fuel load, and water conditions. The top end speed is not always consistant. Somedays I run 80-82 and somedays only 77-78 If your not looking for the ultimate top end your better off with 1.5's. Overall it's a better choice. At least for my boat. Good Luck.

Nordic Heat with 525 xr/its now with labbed 26 bravo.
Prior to gear swap stock 28 bravo.

Last edited by raytart; 10-23-2007 at 06:29 PM.
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Old 10-23-2007 | 06:27 PM
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I think you would be better off with the 1.5
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Old 10-23-2007 | 06:34 PM
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I have not ran the Corsa yet with this power so I'm starting off with no real numbers. My plan is to talk with some people who have experience with this hull. Hopefully some will read this thread Thanks guys.
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Old 10-23-2007 | 08:51 PM
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Originally Posted by GPM
I think you would be better off with the 1.5

I second this
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Old 10-23-2007 | 10:47 PM
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I went from 1.5 Bravo with a 32B to a 1.36 bravo with a 28B and am now with a B-Max with a 1.3 and a 26B. The 1.5 by far outperformed the others. I have no other options under my current set-up and am freshning my motor this season anyway. We will make up for the loss with a little tweaking.
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Old 10-24-2007 | 02:40 AM
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If you are only spinning a 26" prop with a 1.5 then stick with a 1.5. When you get into the 30's for pitch, then think about changing gear ratios.
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