Orenda OE600

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The Orenda OE600 is a 600 hp-class 8-cylinder V-block aircraft engine intended to re-introduce piston power to aircraft normally powered by the famous Pratt & Whitney Canada PT6 turboprop. The piston engine offers much better fuel economy and altitude performance, which Orenda Aerospace felt would be attractive for older aircraft who's engines were reaching the end of their lifespan. However, changes in Orenda's business in the post-9/11 time frame led to the project being canceled.

The engine traces its history to the "Generation 2" Chevrolet Big-Block engines of the 1960s. In 1969 General Motors adapted the engine to use a new aluminum block and pistons rather than cast iron, creating the ZL1. Originally produced to the tune of only 50 examples in 1969 so they could be qualified for the CanAm racing series in the Chevrolet Camaro, additional copies were produced to equip high-end versions of the Chevrolet Corvette, bringing the total production to only 71 examples.

In the 1970s, Lee Muir, a race driver, started adapting the ZL1 for aviation use, adding a large accessories section driven by a gear chain at the front of the engine. For better altitude performance, a large turbocharger was added. The result, known as the Thunder Engine, was shown around the general aviation market during the 1980s. However, financial difficulties led to the project being abandoned after a reported investment of some $5 to $10 million. The engine, designed for short-duration sprints, proved to be difficult to adapt to the long-running high-reliability aviation needs.

Orenda took over development of the engine in 1994. According to their engineers, the engine as it was simply wasn't capable of running at cruise power for extended periods, and required a huge amount of additional development. They completed the certification process in March 1998 as the OE600A. The OE600's "natural" target was the PT6, the most popular turboprop engine of all time. Although a turboprop has a superb power-to-weight ratio, it is also very "thirsty" for fuel, and its performance drops off linearly with altitude. The OE600 offered better gas mileage, as well as considerably improved climb rates (even though it was heavier) and cruise speeds, all suggesting a lower overall cost of operation. On the downside, any piston engine is much more complex than a turbine, so the OE600 initially had a time between overhauls of only 1500 hours, compared to about 10,000 for the PT6. Orenda expected to increase this to 2500 hours by collecting in-service reliability information, but this still represented a major difference in maintenance vs. operational costs.

Orenda and a number of third parties also started the process of developing modification certifications for various popular aircraft. It was tested as a potential replacement engine on a number of aircraft, including the Air Tractor 300 and 400 Series, de Havilland Canada DHC-2 Beaver and Otter, the King Air C90, Aero Commander, and Explorer 500R. Basically any widely used aircraft with an engine around 600 hp was considered as a potential target, which Orenda calculated at about 30,000 flying examples with the PT6, Pratt & Whitney R-1340, Wright R-1820 or various eastern block engines of similar power. Several new aircraft were designed around the engine as well, including the TAI ZIU, Hongdu N-5 and LZ-400 Rhino.

Orenda opened a new service depot known as Orenda Recip at the former CFS Debert in Debert, Nova Scotia. Here they intended to install and service the OE600. At the time they offered a supplemental type certificate conversion for the Otter only, planning to follow this with the King Air. They were also interested in smaller and larger versions of the engine, floating a trial balloon at a 750 hp size (the OE750) before deciding on a naturally-aspirated (sans turbocharger) 500 hp version instead.

Unfortunately the events of 9/11 required Orenda to re-focus entirely on their military projects (or so they claimed), and the OE600 project was canceled. The design was later purchased by a group of investors who intend to sell the engine under the Texas Recip brand, but it is unclear if this project is continuing. On August 29, 2006 the president of Texas Recip, Paul Thorpe was sentenced to 3 years and five months for defrauding investors.