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Today turbo-diesel powertrains offering low fuel consumption and good low-end torque comprise a significant fraction of the light-duty vehicle market in Europe. Global CO₂ regulation and customer fuel prices are expected to continue providing pressure for powertrain fuel efficiency. However, regulated emissions for NO and particulate matter have the potential to further expand the incremental cost of diesel powertrain applications. Vehicle segments with the most cost sensitivity like compacts under 1400 kg weight look for alternatives to meet the CO₂ challenge but maintain an attractive customer offering. In this paper the concepts of downsizing and downspeeding gasoline engines are explored while meeting performance needs through increased BMEP to maintain good driveability and vehicle launch dynamics. A critical enabler for the solution is adoption of gasoline direct injection (GDi) fuel systems.

This paper describes engine research - which supports our program to develop a gasoline engine management system (EMS) with an on-board reformer to provide near-zero tailpipe emissions. With this approach, the reformer converts gasoline (or another hydrocarbon-containing fuel) into reformate, containing hydrogen and CO. Reformate has very wide combustion limits to enable SI engine operation under very dilute conditions (either ultra-lean or with heavy EGR concentrations). In previous publications, we have presented engine dynamometer results showing very low emissions with bottled reformate. This paper shows the sensitivity of engine emissions and performance to operating near the dilute limit with H2 enrichment using both bottled reformate and an actual reformer prototype.

This paper describes recent progress in our program to develop a gasoline-fueled vehicle with an on-board reformer to provide near-zero tailpipe emissions. An on-board reformer converts gasoline (or another hydrocarbon-containing fuel) into reformate, containing hydrogen (H2) and carbon monoxide (CO). Reformate has very wide combustion limits to enable SI engine operation under very dilute conditions (either ultra-lean or with heavy exhaust gas recirculation (EGR) concentrations). In previous publications, we have presented engine dynamometer results showing very low emissions with bottled reformate. This paper shows results from an engine linked to an experimental, fast start-up reformer. We present both performance data for the reformer as well as engine emissions and performance results. Program results continue to show an on-board reforming system to be an attractive option for providing near-zero tailpipe emissions to meet low emission standards.

This paper first reports on the benchmarking of a gasoline- fueled vehicle currently for sale in California that is certified to ULEV standards. Emissions data from this vehicle indicate the improvements necessary over current technology to meet SULEV tailpipe standards. Tests with this vehicle also show emissions levels with current technology under off-cycle conditions representative of real-world use. We then present Delphi's strategy of on-board partial oxidation (POx) reforming with gasoline-fueled, spark-ignition engines. On-board reforming provides a source of hydrogen fuel. Tests were run with bottled gas simulating the output of a POx reformer. Results show that an advanced Engine Management System with a small on-board reformer can provide very low tailpipe emissions both under cold start and warmed-up conditions using relatively small amounts of POx gas. The data cover both normal US Federal Test Procedure (FTP) conditions as well as more extreme, off-cycle operation.

Fuel alcohols, such as M85 (a blend of 85 percent by volume methanol with hydrocarbons) and Ed85 (a blend of 85 percent by volume denatured ethanol with hydrocarbons), are inherently involatile at low temperatures and may contain soluble or insoluble contaminants. We explored the adequacy of existing specifications for M85 and Ed85 by studying fuel effects on cold starting and vapor flammability, and fuel contaminant effects on materials compatibility and filter plugging. These studies demonstrated deficiencies in existing specifications. Therefore, we developed General Motors specifications for M85 and Ed85 to improve vehicle performance and durability. Key features include a Cold Starting Performance Index to improve wintertime starting, a conductivity and chloride ion specification to reduce corrosion, and a particulate contamination limit to reduce filter plugging.

Conventional and speciated tailpipe emissions from a 1992 Chevrolet VFV Lumina were measured to: 1) document differences between M85 and M0; 2) determine whether differences between M85 and M0 were due to the lower sulfur content of M85. The test fuels were M0-A (industry average gasoline), M85-A (a splash blend of 85% methanol and 15% M0-A), and M85-S, which was M85-A doped with thiophene to increase its sulfur concentration to a level equivalent to M0-A. Changing fuel from M0-A to M85-A decreased CO, benzene, 1,3-butadiene, and hydrocarbon-equivalent organic emissions (OMHCE), and reduced both specific reactivity and ozone forming potential of the exhaust. However, methanol and formaldehyde emissions increased. These results are consistent with those of a prototype fleet studied in the Auto/Oil Air Quality Improvement Research Program.

This paper documents the effects of primer composition and concentration on cold starting of 3.1L variable fuel vehicle (VFV) engines with fuel methanol. Primers were restricted to two commercially viable types: full boiling range gasolines and light isocrackate (LIC). Results show that cold starting performance improved with increasing pentane:butane ratio in fuels of equivalent RVP, and improved with increasing primer content. Cold starting performance showed an excellent correlation with vapor-air equivalence ratio (Фfv) and with initial liquid mass fraction of butanes and pentanes; the correlation between cold starting performance and fuel RVP was p.