operable intake valve 16 is advanced to increase trapped fresh charge mass as needed the reverse transition from region 30 to region 36 is accomplished when the trapped fresh charge could be provided by the selectable intake valve 18 alone it may be found that instead of basing the transition on capacity constraint the combustion harshness is the determining factor that is there may be operating conditions that the selectable intake valve 18 alone can provide sufficient fresh charge but the resulting combustion harshness is beyond a desired level in this case a transition from region 36 to region 30 is accomplished based on combustion harshness region 32 or 34 is preferred over region 36 when the following equation holds true in which pwroiv is the pumping work of the engine with the randomly operable intake valve 16 wroiv is the work extracted from the engine to drive the randomly operable intake valve 16 pwsiv is the pumping work of the engine using only the selectable intake valve 18 fwsiv is the friction work lost in driving the selectable intake valve 18 fw u2032 siv is the friction work lost in driving the camshaft of the actuated intake valve when the selectable intake valve 18 is deactivated fw u2032 siv is considerably less than fwsiv but not negligible due to rotational friction in the camshaft even when the selectable intake valve 18 is deactivated clroiv and clsiv are cycle losses associated with operating the randomly operable and selectable intake valves respectively cycle losses are difference between the ideal cycle work that could obtained for an otto cycle and the actual amount.