What engine was in the Chevy Vega?
The Chevy Vega was powered primarily by a 140 cubic inch (2.3-liter) inline-four engine, with a rare Cosworth-tuned variant that used a DOHC setup on the same displacement. This article explains the engines that powered the Vega across its production life and what made the Cosworth upgrade notable.
Baseline powerplant: the 140 cu in inline-four
Overview: The standard Vega relied on a 140 cubic inch inline-four designed for lightness and efficiency during the 1970s, a period marked by fuel concerns and tightening emissions rules. The engine typically used an aluminum block with iron sleeves and was carbureted, with power output that varied by year and configuration.
- Displacement: 140 cubic inches (2.3 liters)
- Configuration: Inline-four with overhead valve design
- Block material: Aluminum block with iron cylinder sleeves
- Induction: Carbureted (configuration could vary by year)
- Production years: 1970–1977
- Estimated output: roughly 90 horsepower in most configurations
The Vega’s lightweight engineering helped it achieve favorable fuel economy for its era, but the aluminum-block design and evolving emissions requirements contributed to durability questions that followed the model through its lifecycle.
Cosworth Vega: the high-performance twist
Overview: In the mid-1970s, GM collaborated with Cosworth to create a performance-oriented variant of the Vega. The Cosworth Vega used a 2.3-liter DOHC inline-four with four valves per cylinder and tuned components to deliver higher output than the standard Vega.
- Displacement: 2.3 liters (140 cu in) in a DOHC configuration
- Valvetrain: Four valves per cylinder with dual overhead camshafts
- Power output: approximately 110 horsepower (varies by year and emissions controls)
- Production: Limited-run, produced during the mid-1970s (commonly cited around a few thousand units, often noted as roughly 3,500)
- Notable features: Cosworth-tuned intake/exhaust and engine management for enhanced performance
The Cosworth Vega remains a standout for enthusiasts due to its rarity and the engineering partnership with Cosworth, even as the powertrain’s era-appropriate limitations and emissions controls tempered its impact.
Summary
In summary, the Chevrolet Vega’s standard engine was a 140 cu in inline-four with an aluminum block design, and a rare Cosworth Vega offered a 2.3-liter DOHC variant that boosted performance. Together, they mark the Vega as an ambitious early-1970s GM compact—light, economical, and emblematic of an era of engineering experimentation.
