In 1974, the 2.3 litres (140 cu in) OHC I4 engine was introduced. This engine was updated and modified several times, allowing it to remain in production into 1997. Among other Ford vehicles, a turbocharged version of this engine later powered the performance-based Thunderbird Turbo Coupe, Mustang SVO, and the European-built Merkur XR4Ti.[1][page needed]