Presented here are the more important results of the past eight years' work at the Pennsylvania State University in the area of ultralean engine operation. It was found that the attainment of reliable lean operation of an SI engine is related to the severity of the cycle-by-cycle (cbc) combustion variations. Discussed are those findings of an intensive study on cbc variations that lead to methods for controlling their severity and ultimately to the extension of the lean misfire limit (lml) to air-fuel ratios in the range of 25:1. The empirical model which resulted from the study of cbc variations and how it was used as a guide for making modifications to the engine intake and ignition systems so as to extend the lml is also discussed. The effect of these modifications on emissions and fuel economy for both conventional fuels as well as for gasoline-methanol blends are presented. They show that ultralean operation is promising because this mode of operation reduces the gas-phase exhaust emissions with no apparent fuel economy penalty. /Author/TRRL

  • Supplemental Notes:
    • This report was presented at the 16th International Automobile Technical Congress.
  • Corporate Authors:

    International Federation of Auto Techniques Engs

    3 Avenue du President Wilson
    F 75116 Paris,   France 
  • Authors:
    • Lestz, S S
    • Meyer, W E
  • Publication Date: 0


  • English

Media Info

  • Pagination: 1 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00163371
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: May 3 1978 12:00AM