Abstract: A cooling system for an internal combustion engine includes a first circuit for cooling the cylinder head and a second circuit for cooling the engine block which are completely separated from each other and make use of a first fluid and a second fluid which are never mixed with each other. The flow of the first fluid circulating in the circuit for cooling the cylinder head is used, totally or partially, for cooling the second fluid which cools the engine block in a heat exchanger. Preferably, the second cooling fluid is the engine lubricating oil.

Abstract: A cooling system for an internal combustion engine of a motor-vehicle has two separate cooling circuits for the cylinder head and the engine block. The cooling fluid which flows through the cylinder head circulates through a radiator in all operating conditions of the cooling system. The cooling fluid which flows through the engine block is instead de-routed so that it does not flow through the radiator and, when it comes out of the engine block, is fed into a conduit at the outlet from the head so that the engine block is kept at a temperature greater than that of the head. An electronic control unit controls the adjustment of a pump for activating the circulation of the cooling fluid, and a flow control valve which de-routes a portion of the cooling fluid at the outlet of the pump towards the engine block. The electronic control unit carries out the above regulations as a function of signals directed thereto from a plurality of sensors which are indicative of a number of engine operating parameters.

Abstract: In a spark ignition internal combustion engine, at least one cylinder is provided in the engine block and a corresponding combustion chamber is formed in the cylinder head for each cylinder. Two intake valves and an exhaust valve are associated with each combustion chamber with the spark-plug for each combustion chamber being arranged in the center between the three valves. The surface of the cavity within the head defining the combustion chamber is roof-shaped with two inclined surface portions in which the two intake ports and the exhaust port are respectively located. In a plane perpendicular to the cylinder axis, the combustion chamber has a pseudo-triangular profile having rounded apices locally following the profile of the three intake and exhaust ports.