RE-OPTIMISATION OF SPARK IGNITION ENGINES

The power output and fuel economy of spark ignition engines is usually optimised for full throttle operation. The work described here is aimed at improving the part load performance of spark ignition engines, the normal operating regime in automotive applications. The experimental work was with a Ricardo E6 single cylinder variable compression ratio engine. Normally the highest useful compression ratio is limited by knock. In these experiments the engine was operated at a higher compression ratio, to benefit from the improved thermodynamic cycle efficiency. To avoid knock at full throttle the ignition had to be retarded, and the fuel/air mixture weakened. This caused a reduction in efficiency that would not occur if higher octane fuel were available. Knock is particularly troublesome at lower engine speeds, and if necessary the throttle opening could be restricted. These controls are now feasible with electronic engine management systems. The results are expressed as fuel consumption maps for different compression ratios, and the fuel economy benefits are estimated for vehicles with CVT and conventional transmissions. The results are reviewed in the context of the predicted fall in fuel octane rating, a fall exacerbated by the restrictions on the use of lead in fuels. One conclusion is that a fall in octane rating should not necessarily lead to a reduction in compression ratios. (Author/TRRL)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/14775360
• Corporate Authors:

  Inderscience Enterprises Limited

  World Trade Center Building, 110 Avenue Louis Casai
  Geneva,   Switzerland 
• Authors:
  • STONE, C R
• Publication Date: 1985-3

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 170-182
• Serial:
  • International Journal of Vehicle Design
  • Volume: 6
  • Issue Number: 2
  • Publisher: Inderscience Enterprises Limited
  • ISSN: 1477-5360
  • Serial URL: http://www.inderscience.com/jhome.php?jcode=IJVD

Subject/Index Terms

• TRT Terms: Combustion; Compression; Continuously variable transmissions; Economic efficiency; Fuel air mixtures; Fuel consumption; Ignition; Improvements; Motors; Octane number; Optimization; Spark ignition engines; Thermodynamics; Transmissions
• Uncontrolled Terms: Efficiency; Optimum
• Old TRIS Terms: Compression ratio; Octane rating
• ITRD Terms: 3860: Combustion; 5911: Efficiency; 232: Fuel consumption; 1327: Ignition; 9108: Improvement; 1334: Motor
• Subject Areas: Economics; Energy; Highways; Vehicles and Equipment;

Filing Info

• Accession Number: 00396799
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Report/Paper Numbers: HS-038 882
• Files: ITRD, TRIS
• Created Date: Jan 31 1986 12:00AM