Re: HP & Torq. Two questions.
Torque is a measurement of generated energy at a specific RPM at the crankshaft...The reason the Federal government required mandatory measurement in hp, at the propeller, in 1988 was to get away from the completely useless idea that torque or the additional measurement in crankshaft hp, in and of itself, had any validity in comparisons of what an outboards useful power output was. As you do not have variable gear ratios in an outboard the comparison model is based on peak hp developed at that prop shaft as that is the last point in the outboards power delivery system. IE Measurement of power previous to the delivery point serves no purpose other than as a curiosity.
Your question(s) of "How much difference is there between horsepower ratings of the early '80's and those of today for a small outboard?
or
How much HP does a outboard loose between the head and the prop?" cannot be answered except in the most general of ways due to all the variables, but, if you want a WAG... Up to 15% on the first and up to 10% on the second.
Your question "Does a larger displacement motor have more torque than smaller displacement motor of the same HP rating?" is an easy answer...It depends
If you are talking identical engine design systems where every single thing is the same other than CID then the answer is bigger has more torque.
