The engine comprises an outer shell in the shape of a fixed ring with two lids, an internal rotor with an inlaid central shaft and bearings. On the inner surface of the shell, inlet, compression, explosion and escape chambers are positioned. The internal rotor is endowed with drive axle having a cylindrical body endowed with radial slots which house at least one vane pressed radially against a shell by spring. The outer shell of the Otto engine has a carburetor and a feed duct of the air-fuel mixture. At the start of the explosion chamber the spark plug is positioned. At the end of the explosion chamber an escape chamber with an escape duct is positioned. The outer shell of the Diesel engine has a butterfly valve and an air feed duct. At the start of the explosion chamber a fuel injection spout is positioned, and at the end of the explosion chamber an escape chamber with an escape duct is positioned.

A moving wall positive displacement turbine system, or moving wall engine, utilizes the relative rotation of a ring, a central body, and a housing with respect to each other to generate power, where the ring is concentrically positioned in a channel between the central body and the housing. The housing and central body remain stationary while the ring rotates within the channel. The channel has low friction walls on either side to reduce friction between rotating components. The ring has a series of vanes passing through it and pivotally attached on each side to the low friction walls in the housing to compress an air-fuel mixture prior to combustion. The system is able to compress and combust an air-fuel mixture to generate direct rotational energy.

A turbo-compounded engine includes a piston engine connected to drive a propulsor. An outlet of the piston engine is operable to connect products of combustion from the piston engine to pass over a turbine. The turbine is connected to drive a turbine shaft also providing rotation to the propulsor. An outlet of the turbine is connected into an exhaust duct configured to exhaust the products of combustion. The exhaust duct is provided with an exhaust duct outer wall defining an exhaust chamber, and a further cooling air outer wall is positioned outwardly of the exhaust duct. Struts connect a cooling chamber between the cooling air outer wall and the exhaust duct outer wall into a center bullet. The center bullet has a downstream end for directing the cooling air into the exhaust chamber at a location upstream of a downstream end of the exhaust duct outer wall.