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VOLKSWAGEN has conducted a number of investigations on a Multi Fuel Vehicle (MFV), designed for variable fuel operation, to determine the influence of fuel composition and clean fuels on exhaust emissions, mainly on ozone forming potential. Results of the tests indicate a small advantage of Phase II Reformulated Gasoline and a greater one for for methanol fuel M85, compared to today's gasoline. For M85 there is an about 25 % lower ozone forming potential. The most critical components in the exhaust of methanol fueled vehicles (M85) are unburned methanol and formaldehyde, forming more than 60 % of the total ozone forming potential. Therefore improvement of cold start and warmup driving during the first two to three minutes is of great importance, because in this time about 90 % of the mentioned components are formed.

The addition of oxygen-containing components into gasoline exerts a sustained influence on the cold start and warm-up performance of vehicles. The influences are shown on the basis of test results with motor vehicles. The cold start performance of vehicles with an alternative fuel such as methanol is very strongly dependent on the composition of a properly tailored fuel. This fuel should contain light boiling components for the best performance. Results from methanol fuelled vehicles under cold climate conditions are shown here. The warm-up conditions of an 1.3 l-engine starting at -10°C were researched. The additional fuel required under these conditions for heating all the components of the egine including the coolant and lubricant was calculated after the basic measurement of their temperature rise. The additional fuel required due to the higher friction was investigated by motoring the engine.

The development of a 1600 can SCE with a divided combustion chamber and fuel injection into the prechamber ist described. Mathematical simulation was used to study the influence of several parameters. Single and multi-cylinder engine tests were carried out to determine the most suitable fuel mass fraction for the prechamber. The effectiveness of the lean thermal reactor was measured. Vehicles were tested accordingly to the CVS-procedure. PNA emissions and octane requirements were also determined. Some limited testing was done with methanol fuel. During the test Programm no specific problems on components were encountered.

The Volkswagen prechamber injection stratified charge concept has a divided combustion chamber with part of the fuel injected into the prechamber and the intake manifold. Various combustion chamber configurations have been investigated in single-cylinder engine tests, and their applicability to the four-cylinder engine is discussed. The development of the third-generation 1.61 air-cooled opposed cylinder engine, along with its mechanical fuel injection system, is described. Engine maps of the prechamber injection engine are discussed, and engine performance data are specified. Test results on the dynamometer show very low nitrogen oxide emissions with fuel economy not impaired; however, hydrocarbon emissions without aftertreatment are still unsatisfactory.