Internal combustion engine with independent control of two or more intake and/or exhaust valves of a cylinder

A valve control system is provided for an internal combustion engine, the engine having at least one cylinder with at least one set of at least two valves, all the valves in the set being either inlet valves or exhaust valves, eg two inlet valves 12, 17 and two exhaust valves 14, 19. One or both of the valves of a set may be controllable independently of the crankshaft, eg by electromagnetic actuators 30, 32. The system is configured to selectively operate the set of valves in a single valve mode of operation over part of the speed/load ranges of the engine during which only one valve of the set is open at any time. The valves of a set may be actuated in a sequence during single valve mode, eg different valves of the set are used for alternate periods of single valve mode operation. Alternatively, the engine may operate for a number of cycles with one valve of a set before a switch is made to the other valve of the set.