Rotax 912 ULS DCDI 100HP

by Michael A. Anderson

Rotax 912 ULS DCDI 100HP*

  • 4-stroke engine specially developed for recreational aircraft. Also exists in a certified version: Rotax 912 S.
  • 4 horizontally opposed cylinders, “boxer” configuration
  • Free air cooled cylinders, liquid cooled cylinder heads with integrated pump and expansion tank
  • Dry sump forced lubrication with integrated pump and separate oil tank
  • 8 valves, automatic adjustment by hydraulic valve tappet
  • Dual Capacitor Discharge Ignition (DCDI) with RFI noise suppression
  • Two Bing Constant Depression (CD) carburetors
  • Mechanically driven diaphragm fuel pump
  • Integrated heavy duty electric starter
  • Integrated reduction gearbox, ratio of 2.43:1 with slipper clutch standard
  • Various liquid and oil radiators available
  • Many option available such as: Vacuum pump, external alternator, hydraulic propeller governor
  • Operates on automotive fuel with a minimum octane rating of 91 (Canadian standards)
  • Time Between Overhauls (TBO): 1500 hours*


Maximum Power*
(5 minutes)
100HP / 73.5KW @ 5800 RPM
Maximum Power (sustained) 95HP / 69.0KW @ 5500 RPM
Maximum Torque 94ft-lb / 128NM @ 5100 RPM
*100HP maximum power when optional air box and tuned exhaust are installed.

Combustion Chambers

Bore 3.31″ / 84mm
Stroke 2.40″ / 61.0mm
Displacement / 1352cm³
Compression ratio 10.5:1


Engine with carburetors 124.7lbs / 56.6Kg
Exhaust System 8.8lbs / 4.0Kg
Air Box 2.9lbs / 1.3Kg
Air Filter 0.7lbs / 0.3Kg
Liquid Radiator 2.2lbs / 1.0Kg
Oil Radiator 1.1lbs / 0.5Kg
Regulator-Rectifier 0.2lbs / 0.1Kg
Installed Weight 140.6lbs / 63.8Kg
Weight/power ratio 1.41lbs/HP / 0.87Kg/KW


Information Sheet 912Sinfo.pdf / 436Kb / Adobe Acrobat format
Performance Graphs 912Sperf.pdf / 14Kb / Adobe Acrobat format
Technical Drawings 912Sdraw.pdf / 537Kb / Adobe Acrobat format
Service Documentation