December 2012
When Continental Motors became part of Teledyne in 1971, engineers had already been at work for several years on the first all-new General Aviation engine to be developed in decades, the Tiara.
The powerplant had relatively small displacement but a good horsepower-to-cubic-inches ratio because it developed its power at high rpms.
The engine’s unique feature was Hydra-Torque drive, a patented system that could be hydraulically locked so the camshaft drove the propeller directly, providing a 0.5 speed reduction. Its singular advantage, according to the engine maker, was that the arrangement eliminated torsional vibration resonance at speeds from idle all the way to the Tiara’s redline at 4,500 rpm.
The first of the planned family of engines was the 6-285. It had a displacement of 406 cubic inches, developed 285 hp at 4,000 rpm and weighed just 382 pounds. A later Tiara, the 6-320, was expected to put out 320 hp at the same weight.
The first problem Continental faced was that while airframe makers were excited about the engine, few were willing to go to the expense of redesigning and recertifying their products.
Then operational problems started popping up on the Tiara. The high rpms—almost twice that of conventional engines—along with the high manifold pressures that were demanded by ag operators began to take their tolls in premature failures of wear parts well before the rather conservative 1,200-hour TBO.
In addition, the General Aviation market was shrinking due to sharply rising costs, and the resulting lack of demand was threatening the very life of Teledyne Continental.
After pouring millions of dollars into the program, the Tiara was discontinued in 1978.
