Is there anything that can be done to my 40 hp Mariner 4cyl to increase power. It seems to struggle under load. I haven't tried switching to an aftermarket prop, but may consider. I'm running the factory aluminum prop now.<br /><br />It's on a 1989 16' Alumacraft tunnel hull. The boat runs great with just myself in it, but if I load it with 3-4 guys, it runs barely above plane.<br /><br />Is the block the same on the 40 hp as the 50 or 60 hp models of the same era?
