Can you modify outboards to increase HP like you can any other engine?

[ShawnQ]

Sorry for the stupid questions guys..I'm a youngster to most of you (19yrs old), and I am new to marine 2 strokes. <br /><br />I am most likely going to rebuild the engine I have (65ESL-72S 65hp johnson 1972), and figured if there was anything I could do, I should do it now!<br /><br />What, if anything, can be done to increase the hp on an outboard without drastically shortening the life of the engine?<br /><br />I used to race 2 stroke karts (kt100 yamahas), and there were a lot of 'tweaks' that could be done to them...but we were rebuilding once a season (6 months)...I realize that this is a whole new ball game, that's why I am asking!<br /><br />Also, the engine I have is old...and it may be too outdated to modify anything. However, I noticed that the other 3 cylinder engines (I believe 50-85hp) have almost all of the same parts. So what makes one more powerful?<br /><br />thanks!<br />Shawn

 

[clanton]

Re: Can you modify outboards to increase HP like you can any other engine?

Try www.screamandfly.com, more Mercury then OMC, but a lot of information.

 

[Chinewalker]

Re: Can you modify outboards to increase HP like you can any other engine?

Hi Shawn,<br /> Is there a lot to be done? Yes. Is it easy? No. Cheap? No. For starters, OMC carried that 50-cubic inche configuration for a generation. It started at 55hp in the late 1960s and evolved to about 75hp in stock trim. The 75hp version had the best of everything in terms of hi-perf. It had bigger carbs, heavier connecting rods, better pistons, etc. than it's predecessors. As the 75 got beefed up, it's slightly detuned twin, the 70, got most of it's improvements (c. late 1970s, early 1980s). The early 3-cylinders would toss a rod at higher revs, which led to the beefier rods on later version. Ignition quality was improved, lower unit configuration was improved. Etc.<br /> Personally, if you like the look and running characteristics of the 65, I'd look for a 70 or 75hp from the late 1970s. The premium one ot look for would be a Johnson Stinger (in 65 or 75hp versions, depending on year), or an Evinrude Hustler. These motors were already tweaked a bit, and besides, they looked cool! The mid-1970s Johnson Stingers were designated the "Mean Machine" and were painted bright orange with black trim! Very cool! The Evinrude Hustler had kind of a Shelby Mustang paint job (all white with blue racing stripes). I've got a 1980 Johnson Stinger 75 with the Checkered flag hood and it's a strong runner on my 15-foot runabout.<br /> Alternatively, you might be able to retrofit a lot of the upgraded parts into your 65hp, foremost being the stronger rods, and related pistons. Might have to look into the port timing, though, as the later pistons might not work in the earlier block. The guys at Scream and Fly can probably give you more tech info on that...<br /> Have fun!<br />- Scott

 

[what200]

Re: Can you modify outboards to increase HP like you can any other engine?

another good place to find knowledgable hot rodders is byuboyz.com or if you like nitrous and smut as a part of your boating experience then havasubarney.com