Abstract: A positive displacement engine with integrated positive displacement rotary fluid compressor has a piston chamber, a piston disposed in the piston chamber, a rotary compressor housing, the rotary compressor housing have first and second interconnected rotary compressor chambers, and first and second rotary compressor elements disposed in the first and second rotary compressor chambers, respectively. The first and second rotary compressor elements each have an elongated arm portion pivotally connected to the piston, and have a generally circular base portion eccentrically pivotally connected to first and second crankshafs. The first and second crankshafts are interconnected to rotate synchronously in opposite directions such that the rotary compressor elements rotate, eccentrically about the crankshafts, within the rotary compressor chambers, synchronously in opposite directions.