Optimal Runner length and port volume have a complete dependency on shape. Best example for "varied CSA for flow" is the funnel-to-nozzle optimized into a venturi.
No intake and head have an optimal venturi. Motorcycle engines come closest.
Dave Vizard shows that an optimized BBC head can make better power by filling the lower 1/4 area to be even better. That data is key to understanding the PMD tall runner shape as a means to make power, while under load.
In other tech:
Still Intrigued that nitro-methane engines make MUCH MORE HP under heavy load than mildly loaded, for same WOT setting.
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