SOAK TIME EFFECTS ON CAR EMISSIONS AND FUEL ECONOMY

Five light-duty vehicles were used to investigate HC, CO, and NOx emissions and fuel economy sensitivity to changes in the length of soak period preceding the EPA Urban Dynamometer Driving Schedule (UDDS). Emission tests were conducted following soak periods 10 minutes to 36 hours in length. HC and NOx emission rates and fuel consumption during the UDDS increased almost linearly with log 10 of soak period length. CO emission rates during the UDDS are stable following soak periods of 10 minutes to 1 hour in length, but the level ranges from 10 to 70 percent of the 16-hour soak value depending on the type of exhaust after treatment. Following 2-hour and longer soak periods, CO increased approximately linearly with log 10 soak length. Soak period length does affect emission rates and fuel consumption during the stabilized portion of the UDDS, but the magnitude of the effect is small compared to that observed during the transient portion.

  • Supplemental Notes:
    • Presented at the SAE meeting, February 27-March 3, 1978.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • Srubar, R L
    • SPRINGER, K J
    • Reineman, M E
  • Publication Date: 1978

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00180104
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Report/Paper Numbers: SAE 780083 Preprint
  • Files: TRIS
  • Created Date: Oct 12 1978 12:00AM