Gasoline internal combustion engine, with a combustion pre-chamber and two spark plugs

A gasoline internal combustion engine, comprising:

• an engine block with a plurality of cylinders and a cylinder head defining a combustion chamber associated with each cylinder of the plurality of cylinders, and at least one intake duct and at least one exhaust duct, provided with respective intake and exhaust valves, associated with each combustion chamber,
• a first spark plug associated with each cylinder, mounted within a support element, which is arranged within a seat of said cylinder head and which defines a combustion pre-chamber having a first end facing electrodes of said first spark plug, and a second end communicating with the respective combustion chamber through a plurality of orifices,
• a second spark plug associated with each cylinder, having electrodes directly facing the respective combustion chamber,
• at least one electromagnetically-controlled gasoline injector device, associated with each cylinder of the engine,
• an electronic control unit, configured to control said first spark plug, said second spark plug and said at least one gasoline injector device for each cylinder of the engine,
• wherein:
• said at least one gasoline injector device comprises one gasoline injector device for injecting gasoline directly into the combustion chamber and/or one gasoline injector device for injecting gasoline into the intake duct associated with said combustion chamber,
• an absence of any device, associated with the combustion pre-chambers, for injecting gasoline or air or a mixture of air and gasoline directly into said combustion pre-chamber,
• said electronic control unit is programmed to control said at least one gasoline injector device to produce an air/gas mixture in said combustion chamber, according to a ratio substantially corresponding to a stoichiometric dose, or a richer dosage than the stoichiometric dose,
• said electronic control unit is programmed in such a way that said second ignition spark plug having electrodes directly facing the combustion chamber is only activated at low and medium engine loads to stabilize the combustion, and is inactive, or kept active but without any influence on the combustion by activating it said second ignition spark plug during an expansion or exhaust stage of the cylinder, at higher loads,
• said combustion pre-chamber is dimensioned in order to reduce a tendency of detonation of the engine at high loads, with a volume less than 0.5% of the capacity of the associated single cylinder of the engine.