I have searched the past posts and have found that there is about 15% disparity between the old horsepower ratings (powerhead) and the new ratings (prop). What I was unable to find was when this rating change occurred. Anyone know the year?
I believe in the 70's-80's, the rating was at the powerhead and later on they started rating them at the propshaft. Not sure of the exact year, though. Also, different models were rated differently in different years. Others will know for sure
