The IROC (which stands for International Race of Champions) was an option package on the Z/28 in the late ‘80s meant to make it go faster. The base engine was the 305ci V8; however, many buyers wisely selected the 230-horsepower, 350ci V8 available with the IROC-Z coupe only.
1985 Camaro IROC-Z | Photo: M62/Wikipedia