X plan marine engine

Looks very much like one smaller version of the GM 16-338 pancake engine, perhaps 16-184s. The 16-338s had rather a chequered career after the war in submarines. Their attraction lay in compactness as the generator was fitted below and allowed a lot less room to be devoted to engines, however they were fraught with problems of oil leakage into generators and actual oil lubrication problems so much so the US Navy took draconian measures and subs were cut in half and lengthened to install conventional engines.

Tom