An engine control system coordinates control of a pressure regulating mechanism associated with a turbocharger turbine and control of a variable valve actuating (VVA) mechanism for expanding the range of possible exhaust gas recirculation rates over a large portion of an engine operating map to provide EGR rates which are greater than typical present-day levels while mitigating engine pumping losses by causing the turbocharger to operate with better efficiency in some regions of the map where it otherwise would not. Turbocharger efficiency is improved by controlling the VVA mechanism to set the timing of operation of its respective cylinder valves in accordance with a predetermined correlation of operating efficiencies of a compressor to timing of operation of respective engine cylinder valves, causing the compressor to operate at points of better efficiency than it otherwise would without use of VVA.