The last couple of years development in aircraft engines has been more or less concentrating on diesels. We have seen one off installations to fully developed production lines. A number of companies are active on this market primarily due to major concern of long term availability and the relative high price of AVgas (Europe).
Diesel engines are able to use JET fuel (AVtur). This fuel is available worldwide and can also be made of renewable sources (algae) which should contribute to a cleaner environment.
Also known as the former Thielert Aircraft Engines (TAE) Centurion now produces and sells the Centurion line of diesel engines for aircraft. This engine is based on the Mercedes class car engine, but heavily rebuild for aircraft purposes and standards.
The company offers with Centurion 2.0 a jet fuel piston engine for general aviation with a takeoff power of 99 kW (135 hp). The Centurion 2.0 is a turbo charged 4-cylinder in-line engine which is EASA certified as off August 2006 and FAA certified from October 2006.
The predecessor Centurion 1.7 is certified by the European Aviation Authorities since May 2002 and the FAA certified since October 2003. The weight of all Centurion 1.7 and 2.0 engines is identical so that the 1.7 can be replaced by a 2.0 engine without any weight and balance issues.
The engines can use a mix of diesel and JET fuel in any ratio, TBR (time between replacement, which is not TBO) is 1500 hours.
At the moment of writing Centurion engines are produced in three versions: 2.0, 2.0s and 4.0 with 135 hp, 155 hp and 350 hp respectively. The 2.0 engines are the same basic design and have a Supplemental Type Certificate for C-172, PA-28, DR400 and Diamond Aircraft, the 4.0 is a huge V8 engine weighing some 272 kg and has flown on a Beach Duke B60 in 2005.
All engines have electronic motor and propeller management with single lever power control, this simplifies pilot operation with enhanced safety. Run-up checks are also automatic after the press of a button. All data is logged during flight in a black box like fashion for later analysis and maintenance purposes. Take-off power is guaranteed up to 10.000 feet and cruise power to 17.500 feet. Maintenance is relatively simple but as the installation seems to be as complex as Rotax, time spent on maintenance could be higher.
Continental markets the CD-135 (specifications) and the CD-155 (specifications) diesel engines based on the TAE-125 diesel by Thielert (wich was originally based on the Mercedes Benz OM668 car diesel). The next link goes to the webite of Continental Diesel.
The basic engine data is in the table below. The 2.0 and 2.0s share the same specifications but the power rating is higher for the s-model. We will not discuss the 1.7 engine as this model is not sold anymore and can be replaced by the 2.0.
| Specifications | Centurion 2.0 and 2.0s |
| Engine | Four inline, four stroke, turbocharged |
| Power | 135 / 155 hp |
| valve gear | DOHC |
| Intake system | Common rail direct injection |
| Cooling | Liquid cooled |
| Oil System | Wet sump oil system |
| Electrical System | Full Authority Digital Engine Control (FADEC) |
| Prop Drive | Reduction gearbox with integrated clutch (ratio i = 1:1,69) |
| Approved propeller | 3-blade propeller of MT with hydraulic variable pitch (MTV-6 series) |
| Displacement | 1.991 cm³, 121.5 cu.in |
| Bore | 83 mm, 3.26 in |
| Stroke | 92 mm, 3.62 in |
| Compression | 18:1 |
| Dimensions (WxLxH) | 778 x 816 x 636 mm, 30.63 x 32.12 x 25.04 in |
| Weight (complete & dry) | 134 kg, 295.4 lbs |
We have left the Centurion 4.0 out of the specifications as this engine is still in development and nothing has been seen since a couple of years. Even on the website of Centurion.aero (redirected to continentaldiesel.com) there is not much to be found about this beast. That is a pity, as it looks like a serious contender for the larger gas engines.
