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In the past application of alternative fuels was mostly concentrated to special markets - e.g. for ethanol and ethanol blends Brazil or Sweden. Now an increasing sensitivity towards dependency on crude oil significantly enhances the interest in alternative fuels. With spark ignited engines, ethanol and gasoline / ethanol blends are the most promising alternative fuels - besides CNG. The high octane number of ethanol and the resulting excellent knock performance gives significant benefits, especially with highly boosted engines. However, the evaporation characteristics of ethanol result in challenges regarding cold start and oil dilution with GDI application. This paper deals with investigations on a turbocharged DI engine operated on ethanol fuel in order to improve challenges of ethanol fuel, such as oil dilution and cold start. Cold start can be improved by injecting fuel late in the compression stroke (high pressure start) based on a refined engine design and operation strategies.

An optical imaging technique has been developed which allows the visual observation of fuel vapour within selected planes in optically accessed combustion chambers of Spark Ignition engines. The technique utilises fluorescence radiation of hydrocarbon molecules to image fuel vapour distribution. This fluorescence radiation is induced by a pulsed laser light sheet projected into the transparent combustion chamber and it can be observed with an intensified camera gated synchronously with the pulsed laser at any selected time instant of the engine cycle. In addition to recording mixture distribution, the camera arrangement also allows visualisation of the gasoline flame propagation. These imaging methods are used for he investigation of mixture formation and flame development in a transparent, disc-shaped combustion chamber under low speed and low load conditions.