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The Thielert Centurion is a series of Diesel cycle aircraft engines for general aviation originally built by Thielert, which was bought by Aviation Industry Corporation of China's Tecnify Motors subsidiary and is currently marketed by Continental Motors. They are based on heavily modified Mercedes-Benz automotive engines.
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Design
All Centurion engines are water-cooled, turbocharged, and employ a single-lever digital engine management system (FADEC). This simplifies engine management for the pilot, as well as improving reliability as it prevents the engine being operated improperly. The series utilizes either jet fuel or diesel fuel. The high compression ratio of the engine combined with the digitally controlled fuel injection system mirrors similar advances in automotive technology.
Centurion series engines are always fitted with constant speed propellers which allow the engine to be operated at optimum speed at all times. However, the normal operating speed is too high for any suitable propeller and so the propeller is driven through a reduction gearbox. The constant speed propeller and reduction gear result in a propeller tip speed that is 10-15% lower than comparable conventional avgas engines, reducing propeller noise.
The Diesel engine's high compression results in better fuel efficiency and the higher operating rpm of the Centurion allows higher power to be developed from a smaller displacement, in comparison to conventional aircraft piston engines.
A Centurion engine complete with CSU, reduction gearbox, turbocharger and FADEC engine management system is considerably heavier than the more conventional Continental and Lycoming engines with which it competes, but this weight disadvantage is compensated by the Centurion's lower fuel consumption. Even though they lack the magnetos and spark plugs of conventional petrol (gas) piston engines, Centurion engines are considerably more complex.
Centurion 1.7 - Continental CD-135
The first product introduced by Thielert, a 1689 cm³ (103 in³) engine producing 135 hp (101 kW) is based on the Mercedes-Benz OM668 engine from Mercedes-Benz A-Class A 170 CDI (W168) with 80 mm bore and 84 mm stroke. Until the end of 2006, when production ceased in favor of the Centurion 2.0, more than 1,500 Centurion 1.7 had been built. The in-service record of the 1.7 has been poor, with a combination of design, service and support issues causing widespread customer dissatisfaction, and resulting in Diamond designing its own engines under the Austro label, as an alternative to Thielert.The engines were later marketed as the CD-135 by Continental Engines. The engines produced in St. Egidien, Germany were granted final assembly in Fairhope, Alabama for the U.S. retrofit market in 2015.