Swap Merc 4.3 for 5.7 ?

[fvshawn]

Hello everyone,
Got my friend into boating, now they want one too. We found a nice Donzi, but owner has swapped the original 4.3 for a 5.7 and retained the original Alpha One leg. My worries is that it may not take the power of this engine for long without failure. Things like lighter components or will it's impeller move enough water for cooling? Please give some advise on Alpa vrs Bravo quickly

 

[Don S]

Re: Swap Merc 4.3 for 5.7 ?

The drive itself will take up to 300 hp, but if it's the original 4.3 gear ratio, it really needs to be changed. Not only is it the wrong gear ratio, but the gears are heavier built on the 1.5 ratio gears.