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The legislative limitations of vehicle exhaust emission together with the current and prospective growth of road transportation intensity calls for continuous effort to improve vehicle powertrains that must be done both in design and technology domains. As the powerful remedy, a new generation of combustion engines fitted with the variable compression ratio (VCR) feature is considered. VCR technology can extend the range of clean engine operations such as HCCI or other advanced combustion strategies, enabling reduction of all exhaust harmful compounds simultaneously. There are several known technologies for performing variable compression ratio in combustion engines; some of them have been successfully tested in engine research rigs and/or vehicle prototypes. In the paper the proposal of application of variable compression ratio technology in four-cylinder, water-cooled engine is presented.

The reduction in the toxic pollutant emissions in diesel engine exhaust gas is one of the main tasks of designers. Toxic substances emitted in diesel exhaust are, among other things, hydrocarbons. Reducing their emissions can be achieved by affecting the exhaust gases or reducing their formation in the combustion chamber. One method is to change the control parameters of the fuel injection process. In the present study, the direct injection diesel engine with a displacement of 1850 ccm was tested. The diesel engine was equipped with a prototype common rail injection system, allowing for the injection of a fuel quantity divided into three parts during one engine working cycle. Each part can be injected when the injector opens at certain injection advance angles. This results in six different control parameters. Such a number of parameters means a large number of combinations.