Preface Since the birth of internal combustion (IC) engines more than 100 years ago@ engine technology has made tremendous progress in terms of efficiency and reliability. In the last two decades@ the environmental implications of engine exhaust emissions have resulted in greater effort in reducing harmful pollutants to meet ever-stringent legislation. Increased knowledge and understanding of the combustion and pollutant formation processes in IC engines are clearly necessary to increase their efficiency and cleanliness@ and to evolve and invent new engines with increased efficiency and lower emissions. The traditional engineering approach has been mostly to treat the engine combustion chamber as a black box and make measurements in the inlet and the exhaust systems. As the processes of improvement in efficiency and emission abatement have reached points of diminishing returns@ there is an increasing need for measurements directly inside the combustion chamber@ where the combustion and pollutant formation processes actually take place. Therefore@ this book is particularly concerned with diagnostic techniques for in-cylinder measurements. The equipment used for exhaust gas measurements are only briefly discussed since these are well established@ and they are readily available commercially. Owing to the wide range of techniques and@ particularly@ the rapid development of modern diagnostics for engine combustion research in the last decade@ it is difficult@ even for a specialist@ to acquire an adequate overview of the achievements in this field. A newcomer to engines research must wade through a number of research monographs and many widely scattered journal or conference papers in order to assimilate the current state of the art and the tools available for research. This is obviously inconvenient for both graduate students or research and development engineers who wish to pursue engines research. While supervising research students and staff in their laboratories and in working with research and development engineers in industry@ we found that@ in the literature@ there is a lack of a systematic approach to engine instrumentation and in-cylinder measurements. The purpose of this book@ therefore@ is to provide@ between one set of covers@ a rather complete description of instrumentation and in-cylinder measurement techniques for IC engines. This book is written primarily for researchers and engineers involved in advanced research and development of internal combustion engines@ as well as for postgraduate students. It provides an introduction to the instrumentation and experimental techniques that are suitable for in-cylinder measurements and@ at the same time@ includes sufficient details for the readers to be able to set up and apply these techniques to IC engines. Additional emphasis here is on the applications of these techniques to improve the understanding of combustion and pollutant formation processes in IC engines.