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An investigation into the application of electronically controlled solenoid activated high pressure in-cylinder gasoline injection systems has been carried out in both conventional and novel four-valve four-stroke pent-roof chamber single-cylinder engines. Air motion requirements were studied and their effects on port design and layout were assessed. Alternative injector types, locations and spray characteristics were investigated. Transient and steady-state comparisons of the engines were made under both normal and cold running conditions. The outlook for the use of in-cylinder injection technology compatible with ULEV emissions requirements is discussed in the light of the results obtained.

A system for stratifying recycled exhaust gas (EGR) in order to substantially increase dilution tolerance has been applied to a single cylinder manifold injected pent-roof four-valve gasoline engine. This system has been given the generic name Combustion Control by Vortex Stratification (CCVS). Preliminary research has shown that greatly improved fuel consumption is achievable at stoichiometric conditions compared to a conventional version of the same engine whilst retaining ULEV NOx levels. Simultaneously the combustion system has shown inherently low HC emissions compared to homogeneous EGR engines. A production viable variable air motion system has also been assessed which increases the effectiveness of the stratification whilst allowing full load refinement and retaining high performance.

To gain a better understanding of the exhaust emissions impact of olefins in a low aromatic, full boiling range gasoline, an evaluation of the before and after catalyst emissions of three highly olefinic refinery streams and three highly paraffinic refinery streams, blended 50/50 in motor alkylate, was conducted using a 3.1 L GM engine. The test fuels were also selected to consider the effects of volatility in addition to olefin concentration. The fuels were evaluated under three steady state engine operating conditions. The results of the tests indicate essentially only small differences in the before and after catalyst total hydrocarbons (THC) between the pairs of highly olefinic streams and the highly paraffinic streams at relatively the same volatility level, for two of the test conditions (2400RPM-light and moderate/heavy loads. The ozone forming potentials (OFP) for these fuels, across all three speed and load conditions, also show relatively small differences.