From Mitsipedia

MIVEC stands for Mitsubishi Innovative Valve timing and lift Electronic Control. It is a form of Variable Valve Timing.

MIVEC varies the lift of valves by using two different camshaft profiles. Instead of having one cam lobe to activate each valve there are two - one is used for low rpm (under 3500rpm) smoothness and the other for high rpm performance. The switch between the two cam lobes is controlled by the engine management computer. As engine RPM increases, a locking pin is pushed by oil pressure to bind the high RPM cam follower for operation.

MIVEC technology is available on vairants of the following engines:

None of the engines fitted to the Magna ever featured MIVEC.