cw77cruiser

I have an OS FS-61M engine that I would like to use in a 31" deep-v but do not know what drive unit would be best with a slower turning 4-cycle engine. These engines do not have the horsepower that the 2-cycles have but they make up for it in torque and down lower in the rpm range. I would imagine that a sub-surface drive would work well but have no experience with this setup, mainly surface drive, and that is on a 36" hydro with a 45. What about the jet drive units out there? Also, I can usually figure out the best prop for a 2-cycle, but I do not know where to begin with a 4-cycle. I do not know how heavy the completed boat will be. If anyone could help, I would be grateful

Ron Olson

My Feedback: (1)

Most 4-cycles that have been converted to marine use have used a gearbox or belt drive system to overdrive the prop. The biggest concern to me is that the engine needs water cooling.
A surface drive would help the prop loosen up enabling the engine to rev up higher.

cw77cruiser

This engine was made by OS for marine use. This is one of the rare water cooled 4-cycle engines made. I could take a picture and post it if anyone is interested.
If I don't have to use a gear box, the better.