The 1990 model year was only a half year of production. Due to the termination of the Chevrolet IROC contract, no IROC-Z's were produced after 12/31/1989. Instead, the 1991 Camaros were introduced early during last half of the normal 1990 model year.

1990 IROC's and RS's are easily identifiable: 1990 was the first year for the updated interior which included drivers side airbag, redesigned instrument panel, yellow lettering on dash, rounded controls. So 1990 IROC's are the only IROC's with the new interior. 1990 RS's are the only RS's with the new interior and the older valances (before the new `scooped' side valances).

The LB8 2.8 liter V-6 was replaced by an increased displacement 3.1 liter LH0 V-6, which means an extra 10 HP.

In 1990, the base engine for the IROC was finally the LB9 TPI 305 rather than the base LO3 V-8. However, G92 had to be specified now to get the better cam/230hp LB9 motor in the 5 speed LB9 IROC-Z. Previously, all 5 speed LB9 IROC-Z's got the higher output LB9. One other dif- ference between a 1989 5.7 IROC and a 1990 5.7 IROC are the pistons. The 350 (only) received lighter weight pistons thus a slight horsepower increase of 240 (1989) to 245 (1990). In 1990, TPI Camaros switched from MAF air metering systems to MAP systems. This eliminated the mass airflow (MAF) sensor.

IROC-Z convertible now came standard with 16 inch wheels and P245/50ZR-16 tires.

G80 limited slip differential became standard equipment on IROC-Z.

The Borg-Warner HD rear end was dropped and replaced with the old 7.625 (7 5/8) inch rear end. Because the Borg-Warner axles were no longer being used for the G92 option, optional axle ratios changed slightly: LB9 305 TPI 5 speed went from 3.45 (1989) to 3.42 (1990) and the B2L 350 TPI went from 3.27 (1989) to 3.23 (1990).

Content of G92 was expanded and purchased as a `performance package' rather than requiring other options. G92 could be ordered two ways: with or without air conditioning. Ordering G92 `without air condition- ing' (C41 standard heater) added the 1LE performance package. G92 performance packages were only available with B2L or LB9/5 speed. All 350 IROC-Z's were required to have one of the G92 packages in 1990.

G92 with air conditioning (C60):
• Optional axle ratio (305/3.42, 350/3.23)
• Rear disc brakes (J65)
• Performance exhaust system (N10) (dual catalytic converters)
• Engine oil cooler (KC4)
• 5.0 liter TPI (LB9) with 5 speed gets revised cam for 230hp rating.

G92 with out air conditioning (C41) in addition to above
adds 1LE performance package consisting of:
• Fog lamp delete
• Aluminum driveshaft (JG1)
• Aluminum spare wheel with smaller spare tire (N64)
• Larger (11.86 inch) front rotors and PBR Australian built HD front dual piston aluminum calipers
• Special swinging fuel pickup in gas tank and special 18 gallon baffled fuel tank for fuel pickup down to .5 gallon reserve to prevent fuel starvation in hard cornering

The 1989 1LE special deflected disc shocks were dropped for the 1990 1LE IROC-Z and standard IROC-Z gas shocks were used.

Quick Facts: 34 1990 1LE LB9 (305 TPI) IROC-Z's were built. 28 1990 1LE B2L (350 TPI) IROC-Z's were built. (Nice)

VIN Example: 1G1FP23EXLL100001 thru 1G1FP23EXLL134986
• Fifth digit is model level: P = Camaro (all models)
• Sixth digit is body style:
  -2 = Hatchback Coupe,
  -3 = Convertible.
• Eighth digit is engine code:
  -F = 305ci V8 (LB9),
  -E = 305ci V8 (L03),
  -T = 191ci V6 (LH0),
  -8 = 350ci V8 (B2L)
• Ninth digit is check digit and varies.
• Tenth digit is model year: L = 1990
• Eleventh digit is assembly plant code: L = Van Nuys
• Last six digits increased one for each car built.

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