Nissan/Tohatsu 4 stroke 8 hp 209cc 5-6k rpm 81 lbs
Nissan/Tohatsu 4 stroke 9.8 hp 209cc 5-6k rpm 81 lbs
Nissan/Tohatsu 4 stroke 9.9 hp 328cc 4.5-5.5k rpm 114 lbs
Honda 4 stroke 8 hp 222cc 5k rpm 92 lbs
Honda 4 stroke 9.9 hp 222cc 5.5k rpm 92 lbs
Suzuki/Mercury 4 stroke 9.9 hp 302cc 5.4-6k rpm 97 lbs
Yamaha/Johnson 4 stroke 8 hp 197cc 5-6k rpm 83 lbs
Yamaha/Johnson 4 stroke 9.9 hp 232cc 4.5-5.5k rpm 91 lbs

Not sure what to make of the Nissan/Tohatsu, but everyone else uses
higher rpms to gain more hp. Says nothing about torque, nor durability.
Price not being an object, I would guess the Honda and the Yamaha 9.9's
would be my preferred engines. The Suzuki is probably not a size issue,
but I don't like the 6k rpm top end of the operating range. If it could
make 9.9 hp @ 5.4k rpm, I'll bet it has more torque than the Honda or
Yamaha.
The 9.9 Nissan is a big engine, guzzles fuel (I know someone pushing a
14' jon boat with one) and is considering the 9.8 hp Nissan as a
replacement. He figures he loses no performance, but probably gains a
bit of fuel economy, while the second may very well be true, I think
he'll lose big time on the performance end.

As a kid we had a 14' Semi-V utility with a mid seventies 5 hp Chryler
that I ran at full throttle whenever I used it. I believe the engine was
too small for the boat. I eventually bent the piston rod, destroying the
motor. My father always blamed it on my over reving the motor. The
replacement motor was an early 1980's vintage 7.5 hp Gamefisher/Eska motor.
This motor was treated a bit more gently the boat and motor were sold
around 5 years ago, still in reasonable shape. Had I beat on it the the
first motor, I doubt we would have gotten 15 years out of it and I
suspect it still runs.
Since those days I've been gentle on my motors and have always thought
it was wise to stay away from the higher hp from smaller displacement
models. I've always thought there's no substitute for displacement.


Clams Canino wrote:
Ummmm................. it's often the other way around.
The lower horsepower / price motor of any given block is often a "crippled"
version of the "bigger" one.

Actually, it's always better to buy the version of the block with the *most*
hp. You get a better power to weight ratio, get better performance, and save
fuel.

-W