How much horsepower does a 1972 Plymouth Duster have?
The horsepower of a 1972 Plymouth Duster depends on the engine it wore. Base models with the inline-six were around the low hundreds of horsepower, while the V8-equipped versions could push into the high hundreds of horsepower on gross ratings, with net ratings typically lower due to emissions-era testing. In short, you could expect roughly 100 horsepower on the entry level, climbing to the low 200s for the more powerful V8s, depending on the specific configuration and rating method used.
Engine options and horsepower for the 1972 Duster
The following sections outline the main powertrains offered for the Duster in 1972 and typical horsepower figures, noting the SAE gross versus SAE net rating systems then in use.
Inline-six and small-block options
These powertrains represent the base and mid-range choices that defined day-to-day driving performance for the Duster. Exact figures vary with carburetion, exhaust, and emission tuning.
- 198 cubic inch inline-six (slant-six): approximately 100–125 horsepower (net), with higher gross numbers cited in older literature depending on configuration.
- Small-block V8 options (predominantly 340 cubic inches and related 360-cubic-inch variants): commonly quoted around 275 horsepower gross for the 340, with net ratings typically in the low 200s, depending on equipment and emissions controls.
- 360 cubic inch V8: strong performer in 1972, with gross horsepower commonly cited in the high 200s and net horsepower generally in the low-to-mid 200s, depending on the build and exhaust setup.
As with most Mopar muscle-era cars, exact horsepower depended on the engine build, optional packages, and the rating method (gross vs. net). Emissions controls implemented in the early 1970s also trimmed real-world output compared with earlier, pre-emissions ratings.
V8 options and performance
The big V8s were the Duster’s performance-focused choices, delivering noticeably stronger acceleration and top-end capability, albeit under the constraint of the era's emissions regulations.
- 340 cubic inch V8: widely regarded as the performance option, with horsepower figures historically cited as around 275 gross; net figures were typically in the low 200s, depending on the particular build and exhaust configuration.
- 360 cubic inch V8: another high-performance option, often listed in the high 200s gross horsepower, with net ratings generally in the 180–210 hp range depending on equipment and emission controls.
Again, the exact numbers vary by the specific engine code, carburation, exhaust, and whether the rating is gross (engine output without accessories) or net (engine output with typical drivetrain accessories attached).
Understanding horsepower ratings in the 1970s Mopar cars
Two rating schemes dominated the era. Gross horsepower measured engine output in a laboratory-style baseline without accessories, while net horsepower reflected what buyers actually felt behind the wheel with typical equipment installed. The shift to SAE net ratings in consumer literature during the early 1970s, along with tightening emissions controls, generally produced lower headline numbers than earlier gross ratings.
Gross vs net: what buyers saw
For a 1972 Duster, the distinction matters. A car advertised with 275 hp (gross) would typically be nearer the low 200s in net horsepower once the belt-driven accessories, exhaust, and mufflers were accounted for. Emissions devices also tended to reduce usable output compared with pre-emission figures.
Summary
In practical terms, a 1972 Plymouth Duster offered a horsepower spectrum from about 100 hp on the base inline-six to roughly 180–210 hp in net terms for the 340 and 360 V8 configurations, with gross ratings often climbing into the mid-to-high 200s for the same engines. The exact figure depends on the engine, options, and whether the rating is gross or net. The Duster’s appeal lay in offering a range of powertrains to suit economy-minded buyers and performance enthusiasts alike.
