Chevrolet · 1974–1976

Chevrolet Cosworth Vega

The Chevrolet Cosworth Vega is a subcompact four-passenger automobile produced by Chevrolet for the 1975 and 1976 model years. It is a limited-production, high-performance version of the Chevrolet Vega. Chevrolet developed the car's all-aluminum inline-four 122 cu in (1,999 cc) engine, and British company Cosworth Engineering designed the DOHC cylinder head. 5,000 engines were built. 3,508 cars were made. They cost nearly twice as much as a base Vega, and only US$900 less than the 1975 Chevrolet Corvette.

Text from Wikipedia (CC BY-SA 4.0).

All Chevrolet Cosworth Vega data: UK builds, safety, recalls, model years →

History

=== Racing origin === Known at Cosworth Engineering as Project EA, a Cosworth racing engine based on the Vega aluminum block produced a reported 260 hp (190 kW) and powered Chevron and Lola race cars to wins in the 2-liter class in their first outings. The Cosworth Vega engine, RPO Z09, is a de-tuned version. Bore, stroke and valve sizes are identical but it lacks the EA engine's dry sump lubricating system, has a lower compression ratio and different valve timing, and uses Bendix electronic fuel injection instead of Lucas mechanical injection to cope with a wider range of operating conditions as well as emission controls. Development. In March, 1970 John DeLorean, GM's general manager and vice-president, sent engine designer Calvin Wade to England in search of cylinder head technology to improve the Vega's performance. Fuel injection would be needed to control emissions without power loss; also stronger internal parts to work with the existing block and the Cosworth head. That summer, DeLorean authorized Wade to build a prototype Cosworth Vega engine. A meager budget, and resistance from managers between Wade and DeLorean, meant low priority for the project, but once approved by DeLorean it could not be killed. In June, 1971 the prototype gave 170 hp (130 kW) on dual Holley-Weber two-barrel carburetors. At Easter, 1972 GM President Edward Cole drove three Vegas for comparison: a base model, an all-aluminum small-block V8-powered prototype, and the Cosworth. He pledged approval from the Engineering Policy Group for DeLorean's request to initiate Cosworth production. Approval of development aimed at U.S. Environmental Protection Agency (EPA) certification soon followed, and Wade began a 12-car development program to accumulate test mileage in a range of environments incl

Overview and changes

All 2,061 1975 Cosworth Vegas were finished in black acrylic lacquer with gold "Cosworth Twin Cam" lettering on the front fenders and rear cove panel and gold pinstriping on hood bulge, body sides, wheel openings, and rear cove. (Black was not offered on other Vegas until mid-1976.) Most have black interiors. The custom interior with perforated vinyl seat trim (RPO ZJ1) was standard, with black cloth seat inserts a $50 option. About 16 percent had white vinyl interiors. All Cosworths had a gold-colored engine-turned dash bezel, gold-plated dash plaque with build sequence number, 8,000 rpm tachometer, and Cosworth Twin-Cam Vega steering wheel emblem. The 'Torque arm' rear suspension is like that of the Monza 2+2, and the axle, from the Monza 2+2, gives a 3.73:1 ratio from a 7.5-inch (190 mm) ring gear. A limited-slip differential was optional. Included were GT springs, shocks, and stabilizer bars (larger at the rear than the Vega GT's); exclusive BR70-13 BSW radial tires on British-made 6 inch, gold-painted cast aluminum wheels with Chevy center caps; black-finished wiper arms, H.D. radiator and provisions for "Fast Steer" option. The Cosworth was the first Chevrolet passenger car with electronic fuel injection. Air conditioning, power steering and power brakes were not offered. A pilot line 1976 model was built in September 1975, and volume 1976 production began in December 1975. A 1976 facelift included wider grille, tri-color tail lamps and extensive body anti-rust improvements. A new Borg-Warner five-speed manual overdrive transmission with 4.10 axle was optional. The exhaust system had a single tailpipe instead of 1975's dual outlets. Seat trim changed to grained vinyl, and the optional extra-charge cloth trim seat inserts were changed to a "houndstooth" type named

Engine

The Cosworth Vega Twin-Cam engine is a 122 cu in (1,999 cc) inline-four with die-cast aluminum alloy cylinder block and Type 356 aluminum alloy, 16-valve cylinder head with double overhead camshafts (DOHC) held in a removable cam-carrier that doubles as a guide for the valve lifters. Each camshaft has five bearings and is turned by individual cam gears on the front end. The camshafts, water pump and fan are driven by a fiberglass cord-reinforced neoprene rubber belt, much like the SOHC Vega 2300 engine. The cylinder head has sintered iron valve seats and cast iron valve seats. Race-bred forged aluminum pistons with heat-treated forged steel crankshaft and connecting rods enhance durability. The engine has a stainless steel exhaust header and Bendix electronic fuel injection (EFI), with four injector valves, an electronic control unit (ECU), five independent sensors and two fuel pumps. Some 60 lb (27 kg) lighter than the SOHC Vega engine, it develops maximum power at 5,600 rpm and is redlined at 6,500 rpm, whereas the SOHC Vega engine peaks at 4,400 rpm and runs to 5,000 rpm. Final ratings are 110 hp (82 kW) at 5,600 rpm, 107 lb⋅ft (145 N⋅m) of torque at 4,800 rpm. 3,508 of the 5,000 engines were used. GM disassembled about 500 and scrapped the remainder.

Reviews

Car and Driver said in August 1973: "Cosworth Vega 16-Valve. More than an engine. A taut-muscled GT coupe to devastate the smugness of BMW 2002tii's and 5-speed Alfa GTV's. A limited run of 4000 machines, each one built away from the tumult of the assembly line to precision tolerances, as a show of technical force by Chevrolet. All of them will be collector's items." The magazine's History of 0–60 article said a 1974 pre-production Cosworth Vega's time of 7.7 seconds was the fastest that year. Testing a 1975 model, the magazine said: "The outstanding feature of the Cosworth Vega is its excellent balance. Roll-stiffness distribution is ideal, with little understeer entering a turn, and just the right amount of drift from the tail as you put your foot down to exit . . . Through the woods or down a mountain, the Cosworth is a feisty aggressor willing, if not altogether able to take on the world's best GT cars." Motor Trend magazine's test of a 1975 version said it "goes like the proverbial bat out of Carlsburg Caverns [...] At moderate speeds, the car is as close to neutral handling as any American car I have ever driven..." The Road & Track test of a 1976 model said: "The Cosworth Vega's handling is very good [...] All the drivers agreed that it is a far better handling car than those Vega derivatives such as the Monza that have been fitted out with V6 or V8 engines [...] We can't resist saying that with the Cosworth Vega engine, the Vega now runs the way it should have run all the time—easy, smooth, good response, good handling: a nice balance between performance and economy. Sweet as it is however, the Cosworth Vega is still way down the excitement ladder from what it would be with another 30 or 40 bhp. Then it would really be something." Road Test magazine, in its 197

Sections adapted from Wikipedia (CC BY-SA 4.0); text is shortened. Read the full article for the complete history and citations.

Specifications

name: Chevrolet Cosworth Vega
aka: Cosworth Twin-Cam
Manufacturer: Chevrolet (General Motors)
Production: March 1974–1976
Model years: 1975–1976
Assembly: Lordstown Assembly-, Lordstown, Ohio, United States
Class: Subcompact
Body style: 3-door hatchback coupe
Layout: FR layout
Platform: GM H platform (RWD)
Engine: 2.0 L DOHC EFI I4
Transmission: 4-speed manual, 5-speed manual w/overdrive (1976)
Wheelbase: 97.0 in
Length: 176.4 in
Width: 65.4 in
Height: 50.0 in
Kerb weight: 2760 lb
Designer: GM & Chevrolet design staff, Chief stylist: Bill Mitchell, Engine designer: Calvin Wade

Specification summary from Wikipedia (CC BY-SA 4.0). Measured facts from Wikidata (CC0). Check the linked sources for citations.

More photos

Sources

Wikidata — https://www.wikidata.org/wiki/Q5094393CC0 1.0 · retrieved 2026-10-01
Wikipedia — https://en.wikipedia.org/wiki/Chevrolet_Cosworth_VegaCC BY-SA 4.0 · Text © Wikipedia contributors; revision 1370076637 · retrieved 2026-10-01
Wikimedia Commons — https://commons.wikimedia.org/wiki/File:76_Cosworth_Vega-blue.jpgCC BY-SA 3.0 · Photo: Barnstarbob/Robert Spinello · retrieved 2026-10-01
Car Model Index — https://models.autoculturesociety.com/Compiled record. Sources that do not permit reuse are not copied; this index is credited instead.