1991 CORVETTE

Not a year of great change after the launch of the ZR-1 the previous year.

• Standard Corvettes were restyled at the rear to more closely resemble the ZR-1 with a convex rear fascia and two rectangular tail lamps on either side of the car.
• A new front end with wrap-around parking lamps was used on both models, along with new side-panel louvers and wider body-color body side moldings.
• Although more alike the standard Corvette in a visual sense, the ZR-1 again had difterent doors and a wider rear to accommodate its 11-inch wide rear wheels.
• Also the high-mounted stop lamp went on the roof of the ZR-1, instead of on the rear fascia, as on the YY Corvette.
• All models were again equipped with ABS Il-S anti-lock braking and driver's side airbag as well as an anti-theft system.
• The ZR-1 was again powered by the 32-valve DOHC 5.7-liter V-8 matched with a six-speed transaxle.
• Corvette models used the 5.7-liter TPI V-8 fitted with the four-speed overdrive automatic or optional six-speed manual transmission.
• Corvette colors were
  • White
  • Steel Blue Metallic
  • Yellow
  • Black
  • Turquoise Metallic
  • Dark Red Metallic
  • Quasar Blue Metallic
  • Bright Red
  • Polo Green Metallic
  • Charcoal Metallic
• Interiors came in Blue; Black; Gray; Red; Saddle; and White.
• Standard features included a removable body-color roof panel for hatchbacks or a convertible top.
• Black, Saddle, Red, White, and (late in the year) Blue top colors were available, but the choices were determined by body paint color.
• Cloth upholstery was also standard.

V.I.N. NUMBERS

• The serial number [Vehicle Identification Number -- VIN] was stamped on a plate on the inner vertical surface of the left windshield pillar visible through the windshield.
• The coupe serial numbers ranged from 1G1YY238*M5100001 to 1G1YY238*M5118595
• The convertible serial numbers ranged from 1G1YY338*M5100001 to 1G1YY338*M5118595
• The ZR1 serial numbers ranged from 1G1YZ23J*M5800001 to 1G1YZ23J*M5802044

Position	Character	Description
1	1	US built
2	G	General Motors product
3	1	Chevrolet Motor Division vehicle
4 & 5	YY	Basic Corvette
	YZ	Corvette ZR-1
6	2 or 3	Body style number 2 = Two door hatchback style 07, 08, 77, or 87 3 = Two door convertible style 67
7	1 or 2	1=Manual seat belts 3=Manual belts with driver-inflatable restraint system 4=Automatic belts
8	8	L98 5.7-liter Tuned-Port-Injection Chevrolet or GM of Canada V8
	J	LT5 - 5.7-liter TPI V-8
9	?	A check digit that calculates the characters in the serial number and gives it a single digit code and can be used to verify that the serial number is legitimate
10	M	The model year where 1991
11	5	Bowling Green, KY
12-17	100001 and up	production sequence for coupes and convertibles
	800001 and up	production sequence for ZR-1s

• Corvette engines have the last six digits of the VIN stamped on the block just ahead of the cylinder head on the right-hand side combined with a three-letter engine code suffix
• Also cast into the top rear of the block is a four-symbol code indicating when the engine was built
  • The first letter of the date code shows the month the block was cast
  • The one or two numbers shows the month
  • The last digit shows the year
• Engine suffixes:

Code	Engine	Horsepower	Compression	Transmission	Fuel	Supply	Extra features
ZTA	L98 350-cid	245/250-hp V-8	10.0:1	automatic	tuned port	injection
ZTB	L98 350-cid	245/250-hp V-8	10.0:1	manual	tuned port	injection	Engine oil cooler
ZTC	L98 350-cid	245/250-hp V-8	10.0:1	automatic	tuned port	injection	Engine oil cooler
ZTK	LT5 350-cid	375-hp V-8	11.0:1	manual	tuned port	injection

• The 1991 Corvette exterior colors were:
  • 10 = White
  • 25 = Steel Blue Metallic
  • 35 = Yellow
  • 41 = Black
  • 42 = Turquoise Metallic
  • 75 = Dark Red Metallic
  • 80 = Quasar Blue Metallic
  • 81 = Bright Red
  • 91 = Polo Green Metallic
  • 96 = Charcoal Metallic
• Upholstery Codes

Color	Cloth Upholstery	Leather Upholstery
Black	19C	193
Saddle	60C	603
Blue		223
Red		733
Gray		903

IDENTIFICATION

Model	Model No.	Body/Style No.	Body Type	Factory Price	Shipping Weight	Production Total
Coupe	1YY	Y07	2-dr. Hatch Coupe - 2 passenger	$32,455	3223	14,967
Convertible	1YY	Y67	2-dr. Convertible - 2 passenger	$38,770	3263	5,672
ZR-1	1YZ	Z07	2-dr. Hatch Coupe - 2 passenger	$64,138	3465	2,044

ENGINE

Feature	Standard Engine (RPO L98)	ZR-1 Engine (RPO LT5)
Type	V-8, 90-degree Overhead valve	V-8, 90-degree Overhead valve with 4 valves per cylinder and 4 overhead camshafts
Block	Cast iron block and aluminum cylinder head	Cast iron block and cylinder head
Displacement	350 cid (5.7 liters)	350 cid (5.7 liters)
Bore & Stroke	4.00" x 3.48"	4.00" x 3.48"
Compression ratio	10.0:1	11.0:1
Brake horsepower	245 @ 4000 (250-hp for hatchbacks using 3.07:1 rear axle due to use of low-restriction mufflers with this option combination only)	375 @ 5800 rpm
Torque	340 lb-ft @ 3200	370 lb-ft @ 5600
Main bearing	five	five
Valve lifters	hydraulic	hydraulic
Fuel supply	Tuned-port induction (TPI) system	Tuned-port induction (TPI) system

TRANSMISSION

• Automatic Transmission
  • Four-speed Turbo Hydra-Matic (TMH 700-R4)
  • floor-mounted gear shifter
  • gear ratios
    • 1st = 3.06:1
    • 2nd = 1.63:1
    • 3rd = 1.00:1
    • 4th = 0.70:1
    • Rev = 2.29:1
  • Final drive ratio: 2.59:1 or 3.07:1
• Four-speed Manual Transmission with overdrive
  • floor-mounted gear shifter
  • gear ratios
    • 1st = 2.88:1
    • 2nd = 1.91:1
    • 3rd = 1.33:1
    • 4th = 1.00:1
    • overdrive = 0.67:1
    • Rev = 2.78:1
  • Final drive ratio: 3.07:1
• Six-speed Manual with overdrive
  • Final drive ratio: 3.07:1

CHASSIS

Feature	Coupe	Convertible	ZR-1
Wheelbase	96.2 inches (2.443 m)	96.2 inches (2.443 m)	96.2 inches (2.443 m)
Overall length	176.5 inches (4.483 m)	176.5 inches (4.483 m)	177.4 inches (4.506 m)
Overall width	71.0 inches (1.803 m)	71.0 inches (1.803 m)	74.0 inches (1.880 m)
Overall height	46.7 inches (1.186 m)		46.7 inches (1.186 m)
Front tread	59.6 inches (1.514 m)	59.6 inches (1.514 m)	59.6 inches (1.514m)
Rear tread	60.4 inches (1.534 m)	60.4 inches (1.534 m)	61.9 inches (1.572m)
Front Tires	P275/40ZR-17 Goodyear Eagle GT	P275/40ZR-17 Goodyear Eagle GT	P275/40ZR-17 Goodyear Eagle GT
Rear Tires	P275/40ZR-17 Goodyear Eagle GT	P275/40ZR-17 Goodyear Eagle GT	P315/35ZR-17 Goodyear Eagle GT
Steering	rack and pinion (power assisted)
Front suspension	Single fiberglass composite monoleaf transverse spring with unequal-length aluminum control arms and stabilizer bar
Rear suspension	Fully independent five-link system with transverse fiberglass single-leaf springs, aluminum upper/lower trailing links and strut-rod tie-rod assembly
Brakes	Four-wheel power disc
Body construction	Unibody with partial front frame
Fuel tank	20 US Gal (16.7 Imp Gal) (76 liters)

OPTIONS

RPO AC1	Power passenger seat	$290
RPO AC3	Power driver seat	$290
RPO A09	Leather sports seats	$1050
RPO AR9	Base leather seats	$425
RPO B2K	Callaway Twin Turbo installed by Callaway Engineering	$33,000
RPO CC2	Auxiliary hardtop for convertible	$1995
RPO C2L	Dual removable roof panels for coupe	$915
RPO 24S	Removable roof panels with blue tint for coupe	$615
RPO 64S	Removable roof panels with bronze tint for coupe	$615
RPO C68	Electronic air conditioning control	$180
RPO FX3	Electronic Selective Ride & Handling system	$1,695
RPO G92	Performance axle ratio 3.07:1	$22
RPO KC4	Engine oil cooler	$110
RPO MN6	Six-speed manual transmission	no-cost option
RPO NNS	California emissions requirements	$100
RPO UJ6	Low tire pressure warning indicator	$325
RPO UU8	Delco-Bose stereo system	$823
RPO UlF	Delco-Bose stereo system with compact disc changer	$1,219
RPO V56	Luggage rack for convertible	$140
RPO Z07	Adjustable handling package (733 were built)	$2,500
RPO ZR1	Special performance package for coupe	$31,683

HISTORICAL NOTES

LITERATURE & LINKS