Complex sentence: In the meantime, the air charge has been easily pushed out of the cylinder and back upstream in the inlet tract where it meets the pressurized charge from the supercharger head-on, causing the inlet pressure to increase just as the inlet port closes.
Split into simpler sentences: In the meantime, the air charge which has been pushed out of the cylinder and back upstream in the inlet tract. There it meets the pressurized charge from the supercharger headon, causing the inlet pressure to increase just as the inlet port closes.