Most likely the world's smallest four-cylinder engine, this tiny aircraft mill is the work of miniaturist George Luhrs, from whose basement workshop has emerged a number of tiny functionals. Not quite new news, the four-cylinder, four cycle ignition engine won first place in the Sherline Machinist's Challenge in 2000. He designed and built it from scratch, taking more than 600 hours to complete it, before being confined to a home for the very, very skilled. More miniature engines here and especially here.[Tech e Blog]

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