Cycle by cycle variability in emissions of a spark ignition engine

E. E. Milkins, H. C. Watson, L. C. Goldsworthy, Richard J. Hallworth

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


The exhaust emissions from a single-cylinder spark ignition engine were measured as a function of burning time. Flame propagation time was measured with an ionization probe, and the exhaust gas was sampled with a gas sampling valve. Electronic control logic determined the cycles to be sampled, based on the flame propagation time. Tests were carried out at full throttle, for lean, optimum, and rich A/F. The exhaust components measured were CO, HC, O 2, H2, and N2 using a gas chromatograph. The emission most affected by CBCV is CO. Cycles that are either faster or slower than the mean cycle have increased CO, particularly at lean A/F where a five-fold difference in CO concentration was measured. HC emissions show a 150% change for the same conditions. For other than lean A/F operation, H2 was an exhaust product, up to 6% at rich A/F operation. It is well established that reductions in CBCV would improve efficiency and power output. Here it is established that a reduction in CBCV would also reduce overall CO and HC emissions, particularly for very lean operation.

Original languageEnglish
Title of host publicationAutomobile Engineering Meeting
StatePublished - 1974
Externally publishedYes
EventAutomobile Engineering Meeting - Toronto, ON, Canada
Duration: Oct 21 1974Oct 25 1974


OtherAutomobile Engineering Meeting
CityToronto, ON

All Science Journal Classification (ASJC) codes

  • Automotive Engineering
  • Safety, Risk, Reliability and Quality
  • Pollution
  • Industrial and Manufacturing Engineering


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