Jet upgade for johnson 90hp??

[spego]

I saw the other posting about a upgrade to increase hp. My dad's 1985 90hp johnson is suppose to be the same motor as a 110 or 120...something like that....don't know too much about johnsons. But anyway he was telling me that with different jets he can get more hp out of it. Does anyone know where to get the jets from? He was not sure and I could not find anything online. Thanks

 

[Dhadley]

Re: Jet upgade for johnson 90hp??

Theres more to it than just changing carb jets. The later 110's have tuned exhaust and better port timing. A 120 is a looper. Youll never get a crossflow to have the power a looper does.<br /><br />Start by figuring out where you are in the efficiency world. Build a map, so to speak. Locate where you are and define where you want to be. Then you can figure out the best route to get where you'd like to be.<br /><br />Post your top rpm with an average load, prop pitch and true top speed. We'll calculate the slip % and then work to reduce that for top efficiency. Also tell us about the boat. What kind of hull design -- V, tri hull, pad bottom, pad and a step, tunnel etc.

 

[JB]

Re: Jet upgade for johnson 90hp??

More mythology, Spego.<br /><br />More fuel without more air will give you nothing but a lousy running engine that sucks your fuel tank 'til it caves in.<br /><br />Bigger jets in the carb WILL NOT increase hp.<br /><br />Good luck.

 

[spego]

Re: Jet upgade for johnson 90hp??

Thats cool guys. Thanks for the info. Just learning more every day.