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The downsized ethanol Spark Ignited Direct Injection (SIDI) engine has proven to be one of the most promising concepts to reduce both the fuel consumption and pollutant emissions. In addition to this engine concept, the use of Fully Variable Camshaft Timing (FVCT) can provide the Internal Exhaust Gas Recirculation (I-EGR) into the combustion chamber. The Cooled Exhaust Gas Recirculation (Cooled - EGR) technique, has been adopted in order to reduce the NOx formation rate. However, through the FVCT system, acceptable levels of charge dilution by I-EGR can be achieved resulting in less fuel consumption and pollutant emissions. In this paper, the I-EGR technique has been investigated by carrying out an experimental analysis of a downsized ethanol SIDI engine running on boosted and unboosted conditions. The results at part load operation present a gain on fuel conversion efficiency due to the I-EGR dilution and the use of de-throttling technique.

The abnormal combustion, such as pre-ignition and knock, are deviations from the controlled combustion process under certain operating conditions, which can result in performance losses and possible damage to the engine. In the SI engines, a pre-ignition event can take place when the flame front is started by any hot spot into the combustion chamber before ignition by the spark plug. The objective of this work is to investigate the use of the Stratified Combustion for Pre-Ignition Suppression (SCPIS) in order to reduce this undesirable phenomenon, especially under high load operating conditions. The results were obtained through dynamometric tests on a downsized ethanol SIDI engine, and considered satisfactory in terms of maximizing the fuel conversion efficiency. The split-injection was studied and adjusted so that the second injection pulse was performed in order to provide satisfactory results of charge cooling effect and, consequently, was effective for pre-ignition suppression.

The current energy and climate world condition presents the need for development of increasingly efficient and sustainable internal combustion engines. In order to meet these requirements, environmental regulatory agencies establish long-term goals of fuel consumption and pollutant gases emissions reduction, which in turn lead the engines to a constant evolution. Thus, this work exploits some recent technologies that tend to minimize the environmental impact of the world’s extensive automotive fleet. Among them, direct injection systems, especially with the use of biofuels, such as ethanol, allow the engine to operate under lean stratified conditions through split-injection. This strategy consists to split several times the fuel injection phase, so that an injection portion can be performed at the intake stroke and the other injection portion at the compression stroke.