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Hybrid electric vehicles (HEVs) are considered as the most commercial prospects new energy vehicles. Most HEVs have adopted Atkinson cycle engine as the main drive power. Atkinson cycle engine uses late intake valve closing (LIVC) to reduce pumping losses and compression work in part load operation. It can transform more heat energy to mechanical energy, improve engine thermal efficiency and decrease fuel consumption. In this paper, the investigations of Atkinson cycle converted from conventional Otto cycle gasoline engine have been carried out. First of all, high geometry compression ratio (CR) has been optimized through piston redesign from 10.5 to 13 in order to overcome the intrinsic drawback of Atkinson cycle in that combustion performance deteriorates due to the decline in the effective CR. Then, both intake and exhaust cam profile have been redesigned to meet the requirements of Atkinson cycle engine.

The aim of this paper is to compare the performance of a gasoline engine fueled with gasoline-Butanol blends of different mixing fractions. Possible causes of the observed differences in performances are analyzed based on Chemical Reaction Dynamics Theory. Influences on other engine performance parameters of different blending fractions are also discussed. It is demonstrated that Butanol is a very promising alternative fuel with great potential for saving energy which has been observed a reduction of 14% in brake specific energy consumption and reduction emissions.