Well put. I like your term "dynamic displacement", it captures the essence of the discussion quite nicely. One of my toys is a '67 GTO that runs a static comp. ratio of 11.31:1, and a DCR of 9.06:1, and all it ever drinks is pump gas. I can pull it off because the cam has very little overlap (read very little scavanging), in fact at .050 lift it is actually -4 deg. overlap.