INTERNAL COMBUSTION ENGINE AND METHOD FOR OPERATING

The present invention relates to an internal combustion engine (10) and to a method for operating a large vessel engine or a stationary engine, which is operable a least in a gas mode. The engine comprises at least one cylinder (11) having an inner diameter (12) of at least 200mm and comprising a pre-chamber, in particular comprising a pilot injection system (13). The engine comprises at least one gas admission valve (14) for supplying fluid fuel to the cylinder (11) , a, preferably low-pressure, exhaust gas recirculation path (16) and a pressure measuring unit (16) with at least one sensor (17) for providing a signal representative of a pressure within the at least one cylinder. The engine comprises a control unit (18) which is configured to receive the signal of the pressure measuring unit, to determine a knock index on basis of the signal, to compare the knock index with a predetermined knock index value or a knock index interval, and to adapt the EGR rate, the time of an ignition event and/or the amount of supplied fluid fuel if the determined knock index is below or above the knock index value or the knock index interval.