The powerplant used in Saturn S-Series automobiles was a straight-4 aluminum piston engine produced by Saturn, a subsidiary of General Motors. The engine was only used in the Saturn S-series line of vehicles (SL, SC, SW) from 1991 through 2002. It was available in chain-driven SOHC or DOHC variants. This was an innovative engine for the time using the lost foam casting process for the engine block and cylinder head. Saturn was one of the first to use this casting process in a full-scale high-production environment. Both engine types used the same engine block.