A variable-displacement, five-cylinder, spark-ignition research engine was designed, fabricated, and is currently under test. This design reduces partial-load fuel consumption by reducing throttling and friction losses. Power is controlled by changing the piston stroke rather than by throttling, except at idle and very low power levels. A linkage arrangement allows for continuous changes in stroke and therefore in engine displacement. The prototype has a bore of 3.375 inches, and stroke varies from 1 to 4-1/4 inches as displacement varies from 43 to 190 cubic inches. The linkage concept is such that clearance volume can be changed in proportion to the stroke. Thus nearly constant compression ratio can be achieved, or by proper selection of the linkage dimensions, compression ratio can be tailored to optimize the design. During design, dynamic analyses of various configurations of the engine were done to determine member loads and unbalanced forces and to assist in selecting the linkage configuration. Dynamic analysis was also used to select five as the number of cylinders, to determine the firing order, to reduce engine vibration, and to compare vibration with that of a conventional engine. Over 100 hours of running time have been accumulated to date, mostly in the range of loads and speeds encountered in typical driving situations. Engine dynamometer tests have resulted in data on power, fuel consumption, and emissions, and the latest test data are presented. Tests demonstrate that a substantial fuel saving can be achieved by using the variable-displacement concept. (ERA citation 02:020388)

  • Supplemental Notes:
    • ERDA contractor's coordination meeting, Ann Arbor, Michigan, United States of America (USA), 17 Oct 1976.
  • Corporate Authors:


    ALBUQUERQUE, NM  United States 

    Energy Research and Development Administration

    20 Massachusetts Avenue, NW
    Washington, DC  United States  20590
  • Publication Date: 1976-10

Media Info

  • Pagination: 25 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00158733
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: CONF-761028-1
  • Contract Numbers: E(29-1)-789
  • Files: TRIS
  • Created Date: Aug 31 1978 12:00AM