Yep, it is strictly VE. Fluid dynamics is complex as you know. But
reversion, the timing of acoustical wave propagation, poppet valve flow
characteristics, and cam overlap all influence the point of maximum cylinder
filling. There is an optimum port velocity affected by all of the above.
However, you will hear numbers ranging from 190 ft/sec up to 650 ft/sec in
magazine articles and blogs. Seeing such a wide range of numbers is more
than suspect! I think the Auto Union Grand Prix had a design port velocity
of about 190-220 ft/sec. It is not all about maximum port velocity or flow
since you have suspended fuel molecules that have to turn corners. The
subject is so complex that Heywood devoted an entire chapter to it. The math
goes beyond me but it is an excellent body of work. Internal Combustion
Engine Fundamentals, John B. Heywood, Chapter 8. -Elon
From: drmayf <drmayf@mayfco.com>
Why does the torque of an engine peak at
some rpm less that what the engine can turn? I am not a motoroligist so
I do not understand. Seems to me that if you can keep the cylinders
filled and then get the compressed air fuel mix lit at the proper time,
then torque should keep going up.
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