Power to weight ratio

[Chris in Indiana]

I have an oddball question. I've run inflatable boats which are unique in that the max hp rating is almost secondary to the max weight rating of the outboard itself. Just recently I purchased a 12 ft Achilles boat with a max rating of 25 hp. So the question is: Whats the best bang for the buck regarding hp vs weight in a Johnson/Evinrude 2 stroke? What would be the best motor for the job? I'm open to stock or modified ideas here. For example I used to own a late 60's Evinrude 9.5 that was very light and zippy (loud though.) As I understood it this motor could be hot-rodded to a 15 or so hp just by changing the carb. Any ideas out there? The max weight rating for the boat is 150lb and clearly a 25hp may push those limits. but I would love to find a way to get 25hp out of 100lb Johnson/Evinrude motor. Any thoughts??

 

[1946Zephyr]

Re: Power to weight ratio

Get a 1972 Johny/Rude 25hp. Good and zippy and relatively light weight.

 

[kbait]

Re: Power to weight ratio

Unless you're filling the boat with gold bars, your issue (for any 25hp) will probably be having a high enough pitch'd prop for max rated RPM's. And '74-'76 9.9's were convertible to 15's w/just carb change. 9.5's ('64-'73) were there own critter.. not really upgradable economically for power.

My preferences would be a '74+ 15hp, or a '57-'70's 18-25hp. 15hp's have good power/weight, idle SLOW all day, and very economical on fuel. Those 18-25's are just powerhouses! Great power/weight. More fuel, but your gold shipment will arrive in a timely manner.