Un-stroked vs Stroked Displacement vs. Crank Angle, etc.

nm9stheham said

No, you're not missing anything..... I just did not know what else to call it besides 'displacement rate'. It's the change in volume in the cylinder as the piston moves down..... in essence, the 'flow rate' if there were were no restrictions in the path of the flow in or out. The peak is the maximal rate of volume change, and is simply the rate of change in the piston position... better known as piston speed!

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Ah, ok. Peak piston speed is not the point of peak cylinder filling - so I would advise that any conclusions brought about by simply looking at that angle will result in huge gains would be a mistake. The rate of acceleration away from TDC is a factor in camshaft design, but the angle of peak piston speed in and of itself isn't a big deal. I use mean piston speed for parts choices but that's it.
It's very well covered in Don Terrill's "The Horsepower Chain". Engine Pro also calculates it easily, although it is a simplified formula according to Don. He breaks the 4 strokes into 7 processes and I think it's a much clearer overall view. Both intake ramming and intake pumping are affected by piston speed, but peak cylinder filling is only distantly influenced by peak piston speed. It's much more complicated than that.