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Continental Tiara series
Tiara 4-180 (O-270)
Tiara 6-260 (O-405)
Tiara 6-285 (O-405)
Tiara 6-320 (O-405)
Tiara T6-260 (O-405)
Tiara T6-285 (O-405)
Tiara T6-320 (O-405)
Tiara 8-380 (O-540)
Tiara T8-450 (O-540)


Continental began development of the horizontally opposed Tiara series in 1965. At the time, CAE, Continental Motor's turbine engine subsidiary, had developed the T65, a small turboshaft engine which was being considered by Bell for its new Model 206 helicopter. Faced with having to fund the production tooling for the T65 in order to keep the price reasonable, or funding the Tiara series, Continental's corporate management chose to invest in the Tiaras.

While the Tiara series were basically traditional boxer engines, they did have some unique features. The engines had high rotational speeds, 0.5:1 gearing was used to reduce propeller speed, with the camshaft forming an extension of the propeller shaft. The propeller shaft featured the Hydra-Torque drive to reduce the shaft's vibrations. The engines were available with four, six- and eight-cylinders. All were fuel-injected, with turbocharging being optional.

The engines' fuel consumption was high, which became a disadvantage during the 1973 oil crisis era. In addition, the Tiaras' performance was not significantly improved over existing engines, making it difficult for aircraft manufacturers to justify the costs of certificating their products for the engines. These problems led Continental to finally discontinue the engines in 1980.


Tiara 4-180 (O-270)
180 hp. Four-cylinder, 271 cu in capacity


Tiara 6-260 (O-405)
260 hp. 406 cu in capacity

Tiara 6-285 (O-405)
285 hp. 406 cu in capacity

Tiara 6-320 (O-405)
300 hp. 406 cu in capacity

Tiara T6-260 (O-405)
260 hp 406 cu in capacity, turbocharged

Tiara T6-285 (O-405)
285 hp 406 cu in capacity, turbocharged

Tiara T6-320 (O-405)
300 hp 406 cu in capacity, turbocharged


Tiara 8-380 (O-540)
380 hp, 541 cu in

Tiara T8-450 (O-540)
450 hp, 541 cu in, turbocharged



Tiara 6
Cerva CE.44 Couguar
Cierva CR.640 (not built)
Piper PA-36-285 Pawnee Brave
Robin HR100/285TR Tiara
Spencer S-12-EAir Car (prototype)
Transavia PL-12 T-320 Airtruk
Trident Trigull (prototypes)



Tiara 6-285-A
Type: 6-cylinder, horizontally opposed piston engine
Bore: 4.875 in (124 mm)
Stroke: 3.625 in (92 mm)
Displacement: 406 in³ (6.65 L)
Dry weight: 375 lb (170 kg) dry
Fuel system: Fuel Injected
Fuel type: 100/100LL avgas
Oil system: 5 US quart (4.7 L), wet sump
Cooling system: Air-cooled
Power output: 285 hp (212 kW) @ 4000 rpm
Compression ratio: 9.0:1



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