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This paper describes the design and performance development of the new Kohler / Lombardini KDI engine range which is a family of 3 and 4 cylinder, in line, water cooled engines covering the power range 37 - 56 kW. The paper covers the following aspects: Performance and economy Exhaust emissions over legislative cycles Deterioration factor test results Effect of fuel quality on emissions

This paper presents the results of an experimental analysis on a multi-cylinder diesel engine, in which in-cylinder pressure and accelerometer transducers are used with the purpose of developing and setting up a methodology able to monitor and optimize the combustion behavior by means of non-intrusive measurements. Previously published results have demonstrated the direct relationship existing between in-cylinder pressure and engine block vibration signals, as well as the sensitivity of the engine surface vibration to variation of injection parameters when the accelerometer is placed in sensitive location of the engine block. Moreover, the accelerometer trace has revealed to be able to locate in the crank-angle domain important phenomena characterizing the combustion process (the start of pre-mixed combustion, the crank angle value corresponding to the beginning of diffusive combustion and to the in-cylinder pressure maximum value).

This work fits into a research program in which the multi-cylinder diesel engine block vibration signal is used with the purpose of developing and setting up a methodology able to monitor and optimize the combustion behavior by means of non-intrusive transducer. Previously published results have demonstrated the direct relationship existing between in-cylinder pressure and engine block vibration signals in a fixed frequency band. It was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, the accelerometer trace has revealed to be able to locate in the crank–angle domain important phenomena characterizing the combustion process.

Many efforts are being currently devoted to the development of diagnostic techniques based on nonintrusive measurements aimed at defining the injection parameters able to optimize the combustion process. Previous papers of the authors have demonstrated a direct relationship between in-cylinder pressure and engine block vibration signals. Besides, it was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, in the accelerometer signal, a frequency band in which such a relationship is very strict has been selected. The aim of the present work is to establish a reliable relation between the main characteristics of the in-cylinder pressure curve and the vibration trend, by means of a deeper insight into the engine block signal. The final objective is to monitor the combustion behavior by means of a non-intrusive transducer.

A methodology has been developed by the authors, in which non-intrusive measurements (engine block vibration) are used for diagnostic purposes of combustion process in Diesel engines. A previous paper of the authors has been devoted to demonstrate the direct relationship between in-cylinder pressure and accelerometer signals, when the vibration transducer is placed in sensitive location. Moreover, in the engine block vibration a frequency band in which such a relationship is very strong has been selected. The aim of this work is to provide a deeper insight into the effects of injection parameters on engine block vibration, in order to investigate the possibility of detecting modification of the in-cylinder pressure evolution by means of the accelerometer signal with the final objective of optimizing the combustion process by means of non-intrusive transducer.

The present work aims at developing and setting up a methodology in which non-intrusive measurements (engine block vibration) are used for monitoring combustion characteristics (combustion diagnosis, combustion development). The engine block vibration appears as a very complex signal in which different sources can be identified, since every moving component or physical process involved in the operation of the engine produces a vibration signal (exhaust valve open/close, inlet valve open/close, fuel injection, combustion, piston slap). Aimed at monitoring the engine running condition, the information carried by the vibration signal has to be broken down into its various contributions and then they have to be related to their respective excitation sources. Concerning combustion-induced vibration, experimental measures has been at first devoted to the selection of the best location where to place the piezoelectric accelerometer.

The paper summarizes the activities related to the characterization of the noise sources and related sound emission levels emitted by a single cylinder diesel engine. A deep analysis is carried out aiming to clearly define the various noise sources, through the employment of numerical and experimental techniques. In particular, an intensimetric analysis is carried out to define a bi-dimensional noise level map around the engine. In addition, the gasdynamic noise, at the different engine speeds, is measured through a microphone mounted near the intake and exhaust mouth. Contemporarily to the experimental activity, a theoretical one dimensional simulation of the whole engine, is also carried out. The presented one-dimensional analysis is able to characterize the wave propagation phenomena in the external ducts and provide the estimation of both engine performance and gasdynamic noise emission too.