valve timing, at all engine loads or speeds, while maintaining efficient
combustion at all times, even during dead slow running. A similar
freedom in exhaust valve timing allows the RT-flex system to keep the
combustion air excess high by earlier closing as the load/speed is
reduced. Such a facility is not only beneficial for fuel consumption; it
also limits component temperatures, which normally increase at low
load. Lower turbocharger efficiencies at part load normally result in
low excess combustion air with fixed valve timing