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The Mercedes D.IV was an eight-cylinder, liquid-cooled inline aircraft engine built by Daimler Motoren Gesellschaft (DMG) and used on a small number of German aircraft during World War I.

Design and development

The design was based around the pistons of the ubiquitous D.III 6-cylinder design and developed 162 kW (217 hp), making it a Class IV motor under the classification system then in use in Germany. It also employed reduction gearing. When the reliability of the engine proved disappointing, it was supplanted in production by the unrelated six-cylinder Mercedes D.IVa. Specifically, the long crankshaft used in extending the original straight-six design to a straight-eight proved susceptible to breakage.



Data from[citation needed]

General characteristics

  • Type: 8-cylinder water-cooled inline aircraft piston engine
  • Bore: 140 mm (5.5 in)
  • Stroke: 160 mm (6.3 in)
  • Displacement: 19.7 L (1,200 in³)
  • Length: 1,990 mm (78 in)
  • Width: 600 mm (24 in)
  • Height: 1,040 mm (41 in)
  • Dry weight: 365 kg (800 lb)


  • Cooling system: Water-cooled


  • Power output: 162 kW (217 hp) at 1,400 rpm


  • Kroschel, Gunter and Helmust Stützer. (1977) Die deutschen Militarflugzeuge 1910-1918 Wilhelmshaven: Lohse-Eissing Mittler.

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