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nova2_excalibur

11-05-2019 01:21 PM

Best drive Ratio Bravo 377 Whipple Engine

Hello,

i have one Question for my drives.
I have two Bravo One with Sportmaster drives, with a 1,65 ratio last year.
In the spring i updatet the two engines ( Mercruiser 377 Mpi) with two Blower kits from Whipple. Its now arround 500-550hp.
So i change the ratio from 1,65 down to 1.33 for drive smaller propellers.

But i think this is not the best idea.
All my friends drive boats with big engines and Propellers from 28-32p. I have now 24p Bravo ones.

When i change back to 1,65 and a larger prop, is this better for the speed?
at this moment i runs 76-78 mph.
before my update i runs 65mph..

thanks.

F-2 Speedy

11-05-2019 02:38 PM

I think you're about maxed on speed with the small blocks, if you want to be like your friends buy a big boat with big power.....:ernaehrung004:...good luck

nova2_excalibur

11-05-2019 02:43 PM

Yes, its a big jump.. i have the gears become for a good price.. and now, i can change back to 1.66 for free..
i turn 5100 at wot

Baja Rooster

11-05-2019 03:42 PM

I’ve asked a few times about optimal drive gear ratios with nothing conclusive other than Fountain used 1.65 drives for better top end speed and folks go to the 1.36 ratio on higher horsepower engines to take it easier on the drive with the smaller props and also for better prop selection. Being that you’re under 600hp I’d think the 1.65 should be fine with the bigger props. I have zero real world experience though.

nova2_excalibur

11-05-2019 05:15 PM

Thanks.. thats that, where i often read.. top end is better with 1.65. the stress sor the drives a little lower at 1.36.
but its only smallblock.. yes it have 500hp, but not the torque as a big block..

Griff

11-06-2019 01:25 AM

If you gain 11-13mph with the whipples and gear change, I'd just leave it alone. Your prop slip numbers for a V bottom boat are great at 7-9%.
I doubt you'll see any big gains going back to 1.65. Your drives should be 1.36 ratio not 1.33.

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