The 1973 Bonneville with the 455 V8 produced about 250 horsepower (SAE net).
In that model year, Pontiac reported power using SAE net ratings, reflecting emissions controls and testing practices of the era. Because of variations in markets, option packages, and whether a car carried different exhaust or emissions setups, the exact figure could shift slightly from one example to another.
Engine configuration and horsepower figures
The core setup for most 1973 Bonneville examples was a 455 cubic inch V8 equipped with a four-barrel carburetor. The horsepower figure most commonly cited for this configuration is around 250 SAE net horsepower.
- 455 cubic inch V8 with a four-barrel carburetor: SAE net horsepower typically around 250 hp in 1973 Bonneville models.
Concluding note: The standard 455 configuration in the Bonneville was not a high-output variant; the commonly cited figure for this setup is about 250 hp, with minor variation based on emission equipment and testing method.
Understanding horsepower ratings in the 1970s
horsepower numbers published in the early 1970s shifted from gross to net testing, and emissions controls continued to affect the figures. For a specific car, checking the window sticker or build sheet provides the most reliable figure, since different sources may quote slightly different numbers.
Context for collectors
The era’s tightening emissions and the oil crisis influenced engine tuning across manufacturers, including large V8s like the 455. If you encounter a Bonneville 455 with a noticeably higher figure, confirm whether the car belongs to another model line or a special-edition variant rather than a standard Bonneville configuration.
Summary: The typical horsepower for a 1973 Bonneville equipped with the 455 V8 is about 250 SAE net horsepower, with minor variations due to testing methods and equipment. For precise verification of a specific car, consult factory documentation such as the build sheet or window sticker.