Combustion engine (10) comprising a stator (11) provided with a compartment (16), inside which a rotor (20) is mounted rotatable, which comprises two parts (22, 23) each comprising a peripheral surface (47) and articulated one with respect to the other and both mounted rotatable, around the same axis of rotation (21) substantially coaxial with the compartment (16). The combustion engine (10) comprises kinematisms (60) to coordinate cyclically the rotations of the two parts (22, 23) around the axis of rotation (21), so that each of the parts (22, 23) accelerates or decelerates synchronously with respect to the other, while still both rotating in the same direction and at the same average angular velocity. Each part (22, 23) comprises a first radial arm (22a, 23a, 22b, 23b) provided with a first lateral surface (45) orthogonal to the plane of rotation, to cooperate cyclically with a corresponding second lateral surface (46), also substantially orthogonal to the plane of rotation, a second adjacent radial arm (22a, 23a, 22b, 23b) to define a combustion chamber (31, 32, 33, 34). The first lateral surface (45) comprises a bevel (36, 37, 38, 39) oriented in the direction of the rotation, to define, with the second lateral surface (46) of the adjacent radial arm (22a, 23a, 22b, 23b), a combustion pre-chamber (40, 41, 42, 43) continuous with the combustion chamber (31, 32, 33, 34).