Knock in S.I. Engines: A Comparison between Different Techniques for Detection and Control

Several knock-detection methods, based both on cylinder pressure analysis and on engine block vibration analysis, have been carefully scrutinized through a critical review of the knock-detection techniques available in literature. Issues have been discussed regarding the physical meaning of knock intensity measurement indexes, mechanical noise sensitivity, transducer type and location, filtering-frequency bands and crank-angle window selection. An experimental investigation has been carried out on a typical European mass-produced engine, and this has provided criteria for the selection of the most suitable and reliable techniques, and has allowed a comparison between experimental results obtained by means of different knock-detection methods.