Chevrolet Camaro IROC-Z28
The third-generation Chevrolet Camaro was introduced for the 1982 model year. It continued to use General Motors's F-body platform through the 1992 model year.
The 1989 model year signified the return of the RS designation. The Rally Sport was now the base model featuring body ground effects mimicking the IROC and the previous Z28 but with the 2.8 V6 fuel-injected motor as standard with the 5.0 305 as an option. The raised rear spoiler that became available in 1988 on the base coupes was short-lived and done away with for this year.The engine ratings carried over from '88 with the addition of IROC-Z Coupes had a new dual catalytic converter exhaust option N10 that was standard with the G92 option only available on the 305 TPI motor with a manual transmission and the 350 TPI only available with the TH700-R4 automatic. Power boosted to 230 HP for the 305 and 240 HP for the 350. Also during this year all Camaros were outfitted with the VATS/PassKey security system and back seats received 3-point safety belts.
IROC-Zs with the TPI 350 had the 2.77 rear axle ratio as in the previous year, but the optional RPO G92 Performance Axle package modified the ratio to 3.27 for the TPI 350, and 3.45 for the TPI 305 with manual transmission. RPO G92 also included the aforementioned dual-converter exhaust; 4-wheel disc brakes (RPO J65); engine oil cooler; P245/50ZR16 Goodyear Eagle unidirectional tires; a 145 mph (233 km/h) speedometer; and a tachometer with a 5,500 rpm redline. Only 1,426 IROC-Z coupes were equipped with the Performance Axle package in 1989.
To take an IROC-Z coupe to the maximum performance extreme in 1989, when G92 Performance Axle was ordered with no air conditioning (C41), RPO code 1LE was automatically triggered. This included extra equipment intended to make the IROC-Z more competitive in SCCA Showroom Stock road racing events: larger 11.65-inch (296 mm) rotors with 2-piston aluminium calipers from PBR; an aluminum driveshaft; a special baffled fuel tank; specific shock absorbers; and stiffer suspension bushings. The fog lamps were also deleted. Since the 1LE was simply an option combination, not a separate package or model which was promoted, very few customers or even Chevrolet dealers were aware of its existence. As a result, only 111 Camaros were built with the 1LE equipment in 1989.
Source: Wikipedia, 2012