Interesting.
Had a
Nissan 2.5 and a
Mercury 3.3 concurrently, and sincerely believed that the 3.3 lower unit was geared lower (slower) than the 2.5 based on counting revolutions. Seemed odd to me. Some time after I
sold the 2.5 I recounted this, and someone who said they were a Tohatsu (or clone)
mechanic stated that this was wrong, that they were identical. I still think I was right, but it didn't make sense for Tohatsu to slow the prop with more horsepower available. All I know is that the 3.3 burned noticeably more
fuel, same
inflatable.
If you can, could you count
engine revolutions per propellor rotation? That would be interesting to compare to my 3.3. I'll have to do this again, myself.
One other oddity about these motors (maybe just those with neutral shifters) was discussed in a previous thread which I will soon post. Several of us have had trouble being able to inject lower unit
oil as is typically done. There seems to a blockage that can occur.