Valvetronic

Valvetronic is a variable valve lift system developed by BMW. Introduced in 1999 on the M52TU engine, it is an evolution of their VANOS variable valve timing system. Valvetronic eliminates the need for a conventional throttle body by controlling engine load solely through the intake valves. The system achieves this by using an eccentric shaft that can adjust the lift of the intake valves.

When the engine requires less power, the eccentric shaft is actuated by an electric motor, causing the intake valves to open less. This effectively throttles the intake air without the pressure loss and pumping inefficiencies associated with a traditional throttle plate. Conversely, when more power is demanded, the eccentric shaft adjusts to allow for greater valve lift.

The primary benefits of Valvetronic include improved fuel efficiency, reduced emissions, and enhanced throttle response. By eliminating the throttle body, pumping losses are significantly reduced, especially at lower engine loads, leading to better fuel economy. The more precise control over airflow also allows for finer tuning of the combustion process, contributing to lower emissions. The direct control over intake air via the valves also allows for quicker reactions to throttle inputs. Valvetronic is a key component in BMW's efforts to optimize engine performance and efficiency.