A turbocharged version was introduced as the pace car at the 1976 Indianapolis 500, and a production turbo arrived in 1978. The turbo 3.8 received sequential fuel injection and a wasted spark Distributorless Ignition System in 1984. In 1986 an air-to-air Garrett intercooler was added and the "RPO Code" became "LC2". The LC2 engine has a bore x stroke of . The horsepower ratings for 1986 & 1987 were , respectively. The limited production GNX benefitted from additional factory modifications such as a ceramic turbocharger, more efficient Garrett intercooler, low restriction exhaust system and revised programming which resulted in a factory rating.