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"Atkinson cam is bunk.."
Well, since the actual Atkinson cycle engine does not make full use of the cylinder's intake "charge" capability it also sacrifices power in favor of efficiency. And remember that during the period the intake valve is left open is exactly in time with the least force capability (just leaving BDC) of the crankshaft acting to force the piston upward.
Also take note that the Atkinson cycle doesn't come up "on the step" except at something like 70% or more cylinder charge. An elongated power stroke does no good unless there is enough charge to be still producing power at or near the bottom of the power stroke.
An ideal system would leave the compression ratio at 13:1 for light cylinder charging, partial throttle, and only go into Atkinson cycle mode at 70% or more of charge.
And by the by, the Atkinson cycle is at its MOST efficient at or near WOT when there is little of NO vacuum in the intake manifold.
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