Hybrid intake system for superatmospheric charging of an engine intake manifold using lowpressure EGR/fresh air blending

An intake manifold (16) of an internal combustion engine (10) is charged to superatmospheric pressure by operating a first compressor (44) to compress fresh air diluted by exhaust gas into the intake manifold while operating a second compressor (24C) to compress undiluted fresh air into the intake manifold through a device (40) that allows flow in a direction from the second compressor into the intake manifold but not in an opposite direction.