Mercury Efficiency Curves?

[Alan454]

Original HP is 330 (flywheel), rebuild Hp is going to be something over 450 Hp with between 550 and 600 ft-lb torque. I assume that the Flo-Torq II hub can handle this right as break-away is advertised as 1000 ft-lb or do I need a solid hub. Boat is a heavy 26' Formula which will weigh about 8250 with 1/2 tank fuel after I replace all my cast with aluminum (except for block).

If 1.5:1 is better is 1.65:1 best? Looks like for 1.5:1 I need 32/27 upper gears, and 1.65:1 would be 30/23. Are these hard to change out or really expensive? Higher P/D ratios can yield higher efficiencies with the higher ratios. What are the real differences between the Bravo I and Revolution props other than the small increase in diameter on Bravo?

thanks
Alan

[Alan454]

The engine torque I gave is flywheel torque, and is multiplied by the Bravo I gears.

600 ft-lbs * 1.36 = 816 ft-lb
600 ft-lbs * 1.5 = 900 ft-lb
600 ft-lbs * 1.65 = 990 ft-lb

Obviously Flo-Torq II can't hande the 1.65:1 ratio. The real question is what is the torque capability of the Bravo I drive?

[Griff]

You need a solid hub. The plastic/delrin hubs are rated for 400hp.