As much as the aviation world hypes up radial engines and V12s, a rather obscure offering from Lycoming is possibly one of the most unique (and best!) sounding engines ever built. The 8-cylinder IO-720 was essentially two 4-cylinder IO-360s bolted end-to-end. First fitted on the Piper Comanche 400 in the late 60s, it made its way to other airframes, primarily as an upgrade. Although the IO-720 was powerful, it was very heavy, guzzled fuel and cost a fortune to overhaul, hence limiting its sales. Nonetheless, it could be found on the following aircraft, featured in this compilation:

00:05 Beechcraft Queenair
4:49 Piper Comanche 400
6:53 Beech Twin Bonanza
8:28 Fletcher FU-24
11:03 Piper Brave
12:44 Helio Courier
12:58 Mike Patey’s Lancair Legacy

Credit to 24HALL for Excalibur footage:
   / @24hall  


One of the most distinguishing features of the IO-720 is its distinct sound, emanating a rumble unique to 8-cylinder engines that captivates any avgeek’s ears. When combined with an augmentor, as seen in the Queenair and Twin Bonanza models, the IO-720 emerges as one of the most exceptional-sounding general aviation aircraft to grace the skies.

What are your thoughts on the IO-720?

Video Credits:
   • N888EK Beechcraft Queen Air Excalibur...  
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