Chevrolet called its 1957 fuel-injection system Ramjet.
The Rochester Ramjet system injected fuel into the intake ports rather than relying on a carburetor. Chevrolet offered it on selected 283-cubic-inch small-block V8s, helping produce the famous advertised output of one horsepower per cubic inch when paired with the appropriate high-output configuration.
The system was developed with Rochester Products and represented an important step in Chevrolet performance engineering. It improved throttle response and high-speed breathing, although it cost more and required more careful service than a conventional carburetor.
“Ramjet” is often confused with later Chevrolet fuel-injection names. Cross-Fire appeared much later, and Tuned Port Injection belonged to the 1980s. Quadrajet was a Rochester carburetor, not the 1957 Corvette-era fuel-injection system.