Tim,
Let's see, 485 ft-lbs @ 6200 rpm, that's 573 HP! Was this where you got
peak torque or peak HP? (Peak HP I assume.) Was that a 350 cu in engine?
I should correct a misunderstanding regarding conclusion #5, which I should
have anticipated. The area referred to is the integrated torque over one
full cycle, i.e., two rotations of the engine. Changing rod length changes
the shape of the curve because of the different rod/crank angles, but the
integral remains constant. This neglects frictional effects, which of
course are greater with the short rods. You talk about running your engine
between 5,500 and 7,400 rpm and maximizing the area under the torque curve.
I think what you need to maximize is the area under the horsepower curve.
Dyno guys like to talk torque, but it's really horsepower that does the
job. The concept of getting the maximum integrated effect is important though.
I'm not sure what to make of the 1 jet size difference. What we'd really
like to know is a comparison of the volumetric efficiency. Generally, a
bigger jet size would suggest better breathing or longer cam duration (but
the cam's the same in this case).
As far a scientific method, yes we'd have trouble publishing your results
as is. One thing not to overlook is the repeatability of the dynamometer.
This can't be taken for granted and, in fact, I understand it's a real
important issue with professional engine builders to keep their dyno
accurately calibrated. Of course, they need a lot better than the ca. 8%
accuracy we're talking about in your case.
OK, back to work now!
Bob
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