gear ratio change ????? - Maxum Boat Owners Club

jobie · 02-26-2011, 03:20 AM

Now that I have determined that my boat (94 2700 scr) came with a Bravo II with 2:0 gears I have a question! While shopping for a used drive I came across a great deal on a Bravo III drive with 2:20 gears. My boat has a 7.4 motor, is this gear ratio a good swap for this boat and if so what props would you recommend?

seapuppy · 02-26-2011, 03:32 AM

well...with any big block....they are usually geared for a few things...like yours..the b2 drive is geared for a large diameter prop.....if you look at the B2 drive props..and a b3 drive props...you notice that the b3 props are quite a bit smaller...but due to the fact that they are counter-rotating props..they will produce more thrust at higher rpms...the main difference between the 2 is really cost...the drive costs twice as much....the props are outragiously expensive.......

so...it really depends on what type of boating your going to do...personally...my 2700 SCR came with the new 6.2ltr mpi engine/b3 drive...now for me ..it was awesome....it was more manuverable than the a1g2 I had with my 2455 ....got on plane easily...I could turn it within it's own boat length...(I can show you how to do it).....
so....the decision is yours.....either would be a great deal....the b2 has tons of thrust but not as effecient as the b3 drive...but...the cost of the drive and props are higher...
the cool thing is that the lower unit can be mounted to the b2 drive upper....they use the same unit...

SP

jobie · 02-26-2011, 05:08 PM

Thanks Seapuppy, it is really the change in gear ratios that I am not sure about

katsal2k · 03-01-2011, 05:11 AM

Jobie, try calling Mercruiser customer support. they were very insightful to Hull wt, altitude, prop size and rpm's.

i upgraded to the 2.43 gears on my last boat. AKA high altitude gears. (original drive had 2.20 gears).
my previous boat was a bayliner 2855, 7.4 efi, bravo 3. At 5400 ft above sea level, the boat took a while to get on plane and once up, topped out at 4000 rpm's. after the gear change the boat was on plane in 7 seconds and wot'ed at 4600. with the same 24 pitch props.

Just curious, what is the great deal on the b3 drive? does it come with a warranty?