help. fitted 2 high reving Mercedes diesel engines to my boat am on bravo 3 outdrive with 1.5-1 gears 22p props it will only get to 1200 rpm 10 mph
max should be 5500 rpm.?? i can exchange gears to 2.0-1 will this do the trick?? the turbos on the engines spool up around 2800 3000 rpm with a bang.
tested on a rough engine dyno to 250 bhp 5500 rpm. if i go 2.0-1 and stay on 22p props will this do the trick ????? thanks ricky . boat is a 28 ft speedboat fast plaining only 6000 lbs all in.

Ricky

Sounds to me like you are running way too much pitch. Are your engines car engines? The reason for my question, is that sometimes carstuff works poorly on boats. If your props are with cup, try a set without cup, they bite less. Your set would run about 63-66 mph, and that is not realistic. 2.0 gears will get you 48-50 mph, so go from there, and try props with and without cup in 22-26 inches of pitch.
You need those turbo's to spool up.

The gear ratio change is going to be a neccesity. The ratio change is good for about 5-6 inches of pitch. This still won't get you to the 5500 mark. However the turbo is going to play into this situation. I wonder if there is something else going on with the engines here?

Brett