1985 Mercury Outboard V-300 V-3.4L Shop Service Manual, Page 21Get this manual
HOW WEATHER AFFECTS ENGINE PERFORMANCE It is known fa ct that weather conditions exert profound effect on power output of internal combustion enginesThereforeestablished horsepower ratings refer to the power thai the engine will produce al it rated RPM under specific combination of weather conditionsThe Engine Test Code of the Society of Au tomot ive Engi neers (SAE) standardizes the computation of horsepower from data obtained on the dynamometer, correcting all values to the power that the engine will produce at sea level in dry air at 60 (l6C) temperature and baromet ric pressure of 29.92 inches of mercurySummer conditions of high temperature, low barometric pressu re and high humidit all combine to reduce the engine powerThisin turnis renected in decreased boat speeds as much as or miles-per-hour in some cases_ (Refer to chart, right Nothing will regain this speed for the boater, but the coming of cool, dry weather
Rated HP
Horsepower ossCondi tions
Due to Atmosphere
Summer HP
}-Secondary loss Due