The intake valve opening and closing events are actuated by Nissans VVEL system. This complicated system uses a rotating eccentric activating a rocker arm with a moving fulcrum which can quickly change the motion ratio of the eccentric to the rocker. This gives the ability to steplessly change the duration and lift of the intake valves on the fly. The command authority of this mechanism over valve moment is great enough so that controlling valve opening is the primary means of controlling the throttling of the VQ37VHR, instead of the throttle itself. 370.com
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