68evin18hp increase to 20???

[Emerald14]

This question was touched on in another post, but I would like to ask outright.<br /><br />It has been mentioned that the 18hp evin (my model #18803M) was the basic format for the 20 and 25hp models offered later. <br /><br />Simply put, would it be reasonable to assume that I could reproduce what the manufacturer "tweaked" in order to increase the HP on my motor? <br /><br />If so, what were the modifications, specifically.<br /><br />Also, what would be the pros and cons of doing so?<br /><br />Thanks for the input.<br /><br />JR

 

[PastorMikH]

Re: 68evin18hp increase to 20???

I'm interested in the same thing.<br /><br />A step further though. With the fact that I have a title to my OB and a lot of the old ones don't, is it feasable to swap a 25 hp johnson/evinrude powerhead with my 18 hp?

 

[Dhadley]

Re: 68evin18hp increase to 20???

18 to 20? Poof! Done! You're welcome!<br /><br />They were exactly the same motor.<br /><br />The 25 had a "balanced" factory crank, a different piston and head. The 25 was rated at a slighly higher rpm. I've not seen a boat yet, other than a full race boat, that the difference showed up on.

 

[Emerald14]

Re: 68evin18hp increase to 20???

Thanks Dhadley<br /><br />Simple answer to my question. The collective knowledge of you folks makes my life easy.<br /><br />JR