The S 6185 engine is one of the oldest produced by FIAT for the naval sector. The construction scheme adopted was quite modern for its time, with the use of various technical features capable of ensuring competitive performance and simplifying control and maintenance operations. The engine on display was produced by FIAT San Giorgio in 1908 for the submarine "Hvalen" of the Royal Swedish Navy (1909-1924), equipped with three independent propulsion units consisting of 6 S 6185 engines coupled in tandem. Each group was connected in series to an electric motor-generator and a propulsive propeller. The submarine was built by FIAT San Giorgio in the Muggiano shipyard near La Spezia; launched in 1909 it remained in active service until 1919. Then it was used for other activities until it sank in 1924. In 1961 the wreck of the submarine was recovered and FIAT took steps to acquire and restore the engine for display purposes, as evidence of its long activity in the naval sector.