Abstract: High-performance internal-combustion engine, particularly of the four-stroke type, including an engine block inside which combustion chambers are formed; each chamber slidingly accommodates a piston and is connected to at least one inlet duct for the air-fuel mixture and to at least one discharge duct for the burnt gases produced by combustion; these ducts are connected to the respective combustion chamber through valves. The internal-combustion engine has the particularity of including a converting-compensating device constituted by at least one pre-chamber mutually connecting at least two inlet ducts and at least one thermal contact chamber which is connected to at least one of the inlet ducts proximate to their outlet leading into the associated combustion chamber. This chamber is formed at the engine head and is in thermal contact with the associated combustion chamber.