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The influence of different port designs on the generation of a swirl flow is described on the basis of stationary and non-stationary flow analyses. Subsequently, engine test bench analyses with a 3-valve one-cylinder engine were performed to assess the aforementioned port configurations with respect to their influence on the lean-burn behaviour. The most favourable port design was then used to analyse various combustion chamber shapes in order to further improve the engine behaviour during lean-burn operation and to select the most promising combustion chamber variant. Finally, the port and combustion chamber configurations thus identified were applied in vehicle simulation tests with lean-burn and EGR-burn operation to check the emission behaviour for compliance with the future European level 3 emission limits.

The principle strategy, the development emphasis, and the investigation parameters of a DI gasoline engine are discussed. Several different combustion systems are briefly described and one system where the spark plug is located near the fuel injector is investigated. In addition, the influence of different operating parameters are studied. Some reasons for the improvement in the efficiency of a DI gasoline engine are shown with the help of thermodynamic analysis and simulation calculations. These show that at a constant operating point (engine speed = 2000 rpm, bmep = 2 bar) there is a reduction of the fuel consumption of 23% at unthrottled conditions in comparison to the homogeneous stoichiometric operation. In particular, the reduction of the pumping and heat losses and the reduction of the exhaust gas energy are responsible for this fuel consumption reduction.

The comparison of a light weight crankcase to the production cast iron crankcase of the new Mercedes Benz 2.9-liter direct injection (DI) five-cylinder turbo diesel engine with intercooler is described. The light weight crankcase is cast from the aluminum alloy A 356 while other engine components like oil pan, timing case cover and brackets are manufactured from a magnesium alloy. This paper describes the engine design with the simultaneous calculation, the mechanical development and the acoustic measurements. In this study an engine weight reduction of about 30 kg with comparable noise emission compared to the production engine with cast iron crankcase is realized.