The turbocharger increases the output of the 3-litre powerplant by 43% with only 7% added engine weight. The turbocharged engine uses a slightly modified version of the indirect-injection prechamber combustion system found in all Mercedes diesel passenger cars. The fuel injection system was adapted to the increased fuel quantity required for a turbo-charged engine, thus permitting a slightly longer injection period which reduces NOx and smoke emissions. The higher cylinder pressures of the turbocharged engine generate stresses in excess of those for which the naturally-aspirated five-cylinder engine's crankshaft is bath-nitrided, which increases its hardness and doubles its fatigue strength under alternating load. It was found necessary to provide internal cooling passages in the pistons. This was accomplished by locating an oil jet near the bottom of each cylinder. The stream of oil is directed upward into an oil-collecting hole in the underside of the piston which carries the oil into a toroidal cooling gallery under the piston head. Valves in the jets shut off these oil streams during idling, to maintain sufficient oil pressure, when piston cooling is not needed. The new engine delivers 6% better fuel economy than the unsupercharged engine when installed in a car weighing 305 kg more.

Media Info

  • Pagination: p. 40-45
  • Serial:
    • Automotive Engineering
    • Volume: 86
    • Issue Number: 6
    • Publisher: Society of Automotive Engineers (SAE)
    • ISSN: 0098-2571

Subject/Index Terms

Filing Info

  • Accession Number: 00183265
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Dec 29 1978 12:00AM