How much horsepower does a 1972 Chevy 402 have?
The 1972 Chevrolet 402 big-block produced horsepower in the mid-to-high 200s in most passenger-car applications, with higher numbers appearing in older, gross-rating figures or in certain performance configurations. In short, expect roughly 270–290 horsepower in 1972 net ratings, with older gross ratings often exceeding 350 horsepower depending on setup.
Understanding the 402 and its 1972 context
The 402 cubic inch V8 is a large-block Chevrolet engine that appeared as a bored/stroked variant of the iconic 396 small- to big-block lineage, used in various Chevrolets and some trucks during the era. By 1972, the automotive industry had begun using net horsepower ratings for new cars, a shift from earlier gross horsepower ratings that were common in the 1960s. This change, along with tightening emissions controls and changes in exhaust and cam profiles, generally reduced published horsepower numbers for the same engines when viewed under the newer standard.
How horsepower was measured then
Two rating philosophies existed side by side for a time. Gross horsepower measured engine output at the crank with minimal accessories, while net horsepower measured output with standard accessories and fabrication that a typical road car would actually employ. By 1972, GM and many other manufacturers published net ratings for passenger cars, which are the figures most people refer to today when discussing a 1970s Chevrolet engine.
Horsepower in 1972: net vs gross
The following guidance clarifies what you’re likely to encounter when researching a 1972 402-equipped Chevrolet, with typical figures for that era and configuration.
Here are the commonly cited numbers you might see for 1972 402 big-block Chevrolets, depending on how the engine was rated and what model it was in.
- Net horsepower (SAE net, typical for passenger cars in 1972): approximately 270–290 hp
- Gross horsepower (SAE gross, older rating used on some catalogs and earlier builds): roughly 380–420+ hp, depending on compression, cam, exhaust, and tuning
- Variations by model and equipment: certain performance or heavy-duty variants could push net ratings toward the upper end of the range, while emissions-equipped configurations or different exhaust setups could lower it
Conclusion: In 1972, the 402’s published horsepower for passenger cars was generally in the upper 200s when using net ratings, with significantly higher gross figures reported in older catalogs or in non-emission-controlled configurations.
Where the 402 showed up in 1972 Chevrolets
Chevrolet offered the 402 big-block in a variety of full-size cars and related platforms. Models commonly associated with the 402 during this era included the Caprice, Impala, Monte Carlo, and El Camino, as well as certain trucks and larger non-passenger applications. Availability and exact power output could vary by market, transmission choice, and the specific emission-control equipment installed on a given vehicle.
Common applications in 1972 included a range of full-size Chevrolets and related body styles that leveraged the 402 for its torque and mid-range muscle while navigating the era’s tightening emissions and fuel-economy expectations. If you’re researching a particular car, checking the original window sticker or the vehicle’s RPO (Regular Production Option) code can confirm the exact specification.
Why numbers vary and what to look for
Several factors determined the published horsepower for a 1972 402-equipped vehicle. Emissions-control equipment (like catalytic converters and exhaust boxes), compression ratio, camshaft design, intake, exhaust manifolds, and even the drivetrain (manual vs. automatic) could all sway the net horsepower figure. Additionally, “402” referred to the engine displacement, but there were different build codes and configurations within that displacement that could yield slightly different outputs.
Bottom line for enthusiasts and researchers
For most 1972 Chevrolet 402-powered passenger cars, you’re looking at net horsepower around the upper 200s (roughly 270–290 hp). If you encounter gross horsepower numbers, they typically sit higher, often in the 380–420 hp range, reflecting the older rating method and fewer emissions controls assumed in those figures. Always note the rating standard (net vs gross) and the specific model/application to interpret the numbers accurately.
Summary
The 1972 Chevy 402 delivered robust performance for its era, with net horsepower commonly in the 270–290 hp range for passenger-car applications, and substantially higher gross figures in older, emission-unced configurations. The exact number varies by model, emission setup, and the rating system used, so checking the precise vehicle’s documentation (RPO codes, window sticker) is the best way to confirm the engine’s output for a specific 1972 Chevrolet.
