1992 Johnson/Evinrude EN 2.3 thru 8 outboards Service Manual, Page 34Get this manual
Weather, Altitude, and Engine Performance The horsepower ratings of all engines are those that would be obtained under standard conditionsHowever, changes in weather and altitude will affect the performance of any outboardSome factors that will decrease the output of an engine are: Low barometric pressure High temperature High humidity High altitude
rv on hot, humid daySometimes the weather an altitude is run Performance can decrease noticeably when engine or alone
can cause the engine RPM to drop below the recommended operating range In any case, top boat speed will not be as high as on cool, dry day