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When Teledyne Continental said it wanted to prove that high-performance engines could operate on unleaded fuel a few months back, it generated some doubting glances. But at AirVenture on Sunday it proved it was serious by flying into Oshkosh a turbocharged Cirrus SR22 tankered with what will eventually become 94UL aviation fuel. Think of 94UL as just like regular avgas, minus the lead. It’s not certified yet nor is the airplane approved to use it, so when Continental lead engineer Keith Chatten gave us a brief demo in the airplane Sunday, we got a look at a test ship. Because 94UL is still a boutique fuel and not available for distribution, our flight trial was on 100LL. The fuel does meet ASTM specs, however.
But Continental had another point to prove: It wants to compete with Tornado Alley for the OEM and aftermarket turbo market with a new 310-HP turbocharged TSIO-550-G. New production Cirrus SR22s are currently equipped with Tornado Alley’s hot selling turbonormalizer system and Continental says it would like to get some of that business back for itself. Accordingly, it plans to offer the turbocharged TSIO-550-G as a drop-in replacement for the turbonormalized IO-550 in the TN Cirrus. TCM’s Rhett Ross told us the engine will be available at an attractive price for owners who wish to convert.
OK, so what’s the benefit? First, says Chatten, the turbocharged airplane climbs and cruises faster than the turbonormalized variant and offers the pilot the option of cruising fast on more fuel, but also the ability to throttle back and run lean of peak. Further, TCM claims the TSIO-550’s 7.5-to-1 compression ratio pistons offer better margin against detonation than do the turbnormalized engine’s higher compression pistons. Moreover, claims TCM, the TSIO-550 will do that on 94UL, with only slight cooling problems at warmer than standard days at high altitude.
On our brief flight, we didn’t see any temperature issues on a max effort climb to 10,000 feet. Cruise performance at 10,000 feet was about 191 knots on 25.5 GPH leaned to about 75 degrees rich of peak. That’s high cruise. Hottest CHTs were in the 370 to 380-degree range. A more realistic cruise 75 degrees rich of peak we saw 210 knots at 22 GPH. The engine also appeared to run smoothly lean of peak at 16.7 gallons and about 184 knots. When TCM is further along with the project, we’ll compare it directly to the Tornado Alley system via flyoff. TCM is still in the testing phase of the TSIO-550 and initially projects availability sometime in 2010. 94UL is on the table with industry groups and the FAA for certification, after which the oil companies will have to decide if they want to refine and distribute it.
