Flying a Big-Bore Engine Without the Lead

Isabel Goyer

Thursday, November 19, 2009 at 09:59 AM ET

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Cirrus SR22 Turbo

Key Takeaways:

The author test-flew a Continental-modified Cirrus SR22 on 94UL unleaded fuel, showcasing a promising future for big-bore engines amidst the upcoming industry-wide shift from 100LL.
Continental Motors is proactively addressing the mandatory 2017 transition from 100LL by both modifying existing gas piston engines for unleaded fuel (e.g., TSIO-550) and developing new jet-A burning diesel engines.
The test flight demonstrated impressive performance on 94UL, with the modified TSIO-550 engine delivering more power on takeoff/climb and running cooler than a standard engine on 100LL, even under challenging conditions, thus dispelling fears about unleaded fuel in high-performance engines.

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My test flight in Continental Motors’ developmental Cirrus SR22 was among the most unusual and interesting of my career. That was in part because I was testing a major mod of an airplane in which I have a lot of flying experience, and in part because I was glimpsing into the future by flying a big-bore-powered airplane using unleaded fuel.

The airplane I flew was topped off with 94UL in Mobile, Alabama, that morning. By the time it made it out to Austin, Texas, we still had a couple of hours of unleaded fuel, enough to see how the TSIO-550 performed on 100-No-Lead before adding 100LL for the remainder of the flight.