Re: WOT speed on a '83 20' SF w/200
"horsepower, it don't matter what color the engine is."
Shame on you Blue Heron; you obviously know better.
For one thing Horsepower ratings are as much marketing hype as engineering (and all indications are that Mercury is more of a sales organization than an engineering one)
Then there is this business of power curves where power and torque vary with engine design for any given RPM.
There are known occurrences of horsepower being overrated 20% or more by marketers so a spread of 40 HP DOWNWARD is certainly possible.
In which event would be inclined to trust Yamaha's (or just about anyone's) veracity over Mercury.
As you can tell, have gotten a pretty low opinion of Mercury Marine.
Oh, and BTW, is the cam on your FrenkenMerc engine in sync with the other volumetric components (valve lift versus area, versus open (or close) time)? Have you checked breathing?
Regards, HBH
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