Thinking about it - one reduction in this number may be made when reviewing the actuall cylinder pressure just before Inlet Valve closing. I'm not sure how much of an effect it would have, since at valve closing, I've assumed the prs in the cylinder is equal to the inlet plenum pressure (say 14.5psi). It may be marginally less than this 'cause the inlet valve inlet velocity may behigh and hence there may be some losses here.
Having said that if you look at the attached figure - the cylinder may well be on its way back up by the tme the inlet valve is closed.
See attach.
Total Inlet stroke (84mm) at 6200rpm is only 4.8 milliseconds, so that means the cylinder is travelling at an average (sinusoidal) rate of 17.8m/s (100miles/hr!).