In the early 30s, in the prelude to WWII, the US Army and the US navy needed production engines that could meet or exceed the 1 hp per cubic inch benchmark. At the time, that power output had only been achieved by several purpose-built racing engines, but no reproducible production engine had yet fulfilled this need. As a result, the US government financed several “high-performance” or hyper-engine projects, and in today’s video, we’ll be taking a look at some of these incredible, forgotten pieces of engineering…

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00:00 - Start
00:27 - XI-2220
04:32 - Lycoming 7755
06:50 - Wright - R-2160
08:22 - Pratt & Whitney Sleeve Valves
09:40 - Conclusions