The BMW 803 was BMW's attempt to build a high-power aircraft engine by "coupling" two BMW 801s back-to-back driving contra-rotating propellers. The result was a 28-cylinder 4-row radial engine, like the contemporary American Pratt & Whitney R-4360 Wasp Major of 17% smaller total displacement, but unlike the American engine, due to cooling concerns the 803 engine was liquid cooled.
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