An integrated rotary expansible chamber device comprises a compressor and a pneumatic motor housed within a single engine block. The pneumatic motor includes a cylindrical casing having a pressurized gas inlet, an exhaust outlet, and an off-center output shaft with a rotor mounted on it. The rotor have spring-loaded radially sliding vanes. The vanes sealed with the casing wall by pivoted shoes. The pneumatic motor powers the compressor, supplying compressed air to a combustion chamber, which produces pressurized combustion gases to drive the pneumatic motor. The device incorporates a recess for gradual (extended) exhaust gas release, air and fuel storage tanks for rapid starting without a starter motor. In another embodiment, the pneumatic motor consists of cylindrical casing with centrally meshed radial vanes mounted on coaxial shafts, driven by inverted crank slider mechanism in the adjacent drive box. This embodiment feature labyrinth sealing for oil-free operation and versatile functionality.