Abstract: A system and method to control valve timing and valve lift of an engine is described. The intake valve timing can be retarded while the valve is in a low lift or high lift mode. The method can lower engine friction and reduce fuel consumption, at least under some conditions.

Abstract: A system and method to control valve timing and valve lift of an engine is described. The intake valve timing can be retarded while the valve is in a low lift or high lift mode. The method can lower engine friction and reduce fuel consumption, at least under some conditions.

Abstract: A four-stroke cycle reciprocating internal combustion engine includes a piston mounted for reciprocal movement within a power cylinder and primary and secondary intake valves. The primary valve has a fixed event, in terms of both duration and lift, and the secondary valve has variable duration and lift. Although the timing of the primary and secondary valve events may be retarded from a standard timing value, both valves close at the same time regardless of the presence of timing retard. The dual event strategy, combined with camshaft timing retard for part load conditions, produces excellent charge motion by staggering the respective lifted flow areas of the primary and secondary valve events and by delaying the secondary valve opening.