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  • Continental Motors CD-155; The Multi-fuel Diesel Engine for Aircraft

Continental Motors CD-155; The Multi-fuel Diesel Engine for Aircraft

This High-Flying Engine Keeps Aircraft Aloft Worldwide

John Lehenbauer
Dec 7, 2016
Photographers: Manufacturer
Continental Motors was founded in 1905 and introduced its first aircraft engine, the Type “O,” one year later. In 1929, the company began production of radial engines for general aviation. Since then, Continental has also developed flat, horizontal, and gasoline-burning powerplants that are powerful, lightweight, efficient, and environmentally friendly.
However, in 1997, NASA selected Continental Motors to develop a new engine for the General Aviation Propulsion program. The goal of GAP was to build an inexpensive piston engine that did not rely on leaded gasoline. It needed to be more reliable, maintainable, and efficient, while still being easy to operate. The partnership led to the development of a diesel engine that ran on Jet-A fuel. Jet-A (kerosene) was developed for use in turbine engines and works on the same principles as diesel fuel in a compression-ignition engine. In 2001, the work with GAP helped Continental become the first manufacturer to receive Federal Aviation Administration and European Aviation Safety Agency approval for a small-aircraft diesel engine, the I-4 Centurion 1.7. That first certified oil-burner led to the continued development of quieter, more reliable, and more powerful units, such as the Continental Motors CD-155.
The CD-155 is a modern turbocharged, DOHC, common-rail, direct-injected diesel engine that is capable of making 155 hp and 349 lb-ft of torque at the propeller. An engine-mounted gear-reduction box transfers power to the prop, via a 1.69:1 gear ratio and an integrated clutch.
Photo 2/3   |   The all-aluminum Continental Motors CD-155 is an FAA- and EASA-certified diesel aviation engine. The turbocharged oil-burner can run on diesel, Jet-A fuel, or a mixture of the two in any ratio.
In aviation, like many other forms of transportation, having a good power-to-weight ratio is crucial for an engine’s operational efficiency and a vehicle’s handling characteristics. Because of this, Continental Motors designed the CD-155 to be as lightweight as possible without sacrificing any strength or reliability. The engine features a pressure die-cast aluminum crankcase to save weight and withstand high combustion pressures, and a plasma coating resists wear in the cylinder walls. Further weight saving comes from a cast-aluminum cylinder head and aluminum pistons. Steel inlays are used in the piston rings’ grooves to increase strength and act as cooling ducts. Special chrome-ceramic piston rings further increase the wear resistance in the cylinder.
The CD-155’s design and Full Authority Digital Engine Control engine-management system allow it to run using a broad range of fuels. It can run on three certified fuels (diesel, Jet A, and Jet A-1) and six other usable fuels (JP-5, DEF STAN 91-86, JP-8, DEF STAN 91-91, JP-8+100, and Chinese Jet Fuel No. 3). The engines are certified to run with both jet fuel and diesel fuel mixed together in any ratio. The worldwide availability of diesel and jet fuel (99.5 percent of aviation fuel delivered worldwide) makes it a very appealing global powerplant.
The use of kerosene allows the engine to produce less nitrogen oxide and hydrocarbon emissions while eliminating the possibility of carbon monoxide poisoning. The CD-155’s robust design allows it to handle the high pressures in the combustion chamber and provide reliability that makes it well suited to aviation.
Photo 3/3   |   The engine-mounted gear-reduction box decreases the final drive ratio by 1.69:1 at the propeller.


Engine: Continental Motors CD-155
Displacement: 2.0L (121.5ci)
Engine Layout: I-4
Valvetrain: DOHC
Bore x Stroke: 3.26 x 3.62 inches (83 x 92mm)
Compression Ratio: 18:1
Head material: Aluminum
Block material: Aluminum
Piston material: Aluminum
Power: 155 hp at 6,000 feet (altitude)
Torque: 349 lb-ft at propeller
Induction: Variable geometry turbocharger
Exhaust: Cast-iron manifold
Cooling System: Liquid cooled
Fuel System: Common-rail direct injection
Lubrication System: Wet sump
Lubrication Capacity: 4 quarts
Dry Weight: 295.4 pounds
Length: 32.12 inches
Width: 30.63 inches
Height: 25.04 inches


Continental Motors
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