"Yes, the 1970, 90 horse was r
"Yes, the 1970, 90 horse was rated in Brake Horse Power (BHP), but they were a little loose with the ratings as well - no EPA looking over their shoulder back then.
A 90 BHP would roughly equate to between 82-85 Shaft Horse Power (SHP) the modern measure.
But if they were off by say 8-10% in the first place, that 90 BHP may have been putting out as much as 99 horses, which when converted to the modern standard would still be a 90-95 horse motor.
A new motor will usually have less than a 5% variance from what the decal says. That way they get the EPA stamp of approval for emissions.
So basically, anything less than 100 horses, whether old or new, would be putting out similar horsepower....
If you look back through the mid 80's you will notice a couple of models that "went away" or changed.
If you look for a 150 Evinrude, you will see the following year they marketed a 135 model - same motor, they just adjusted the rating to reflect the SHP numbers."