a device and method for double actuating , by pressure differential , a valve of a combustion chamber of an internal combustion engine , wherein the double actuating device comprises an actuator piston displaceably arranged in an actuator cylinder between two chambers of inversely varying volume , mechanically attached to the stem of said valve . the actuating forces on said valve are selectively controllable via pressurized manifolds . the valves are double actuated independently of engine operation , the method allowing for variation in timing , duration , and lift under an electronically controlled fluid circuit , using alterable constants to allow for modifiable operating modes , also allowing reprogramming of said electronics to provide for in - place upgrades .