Ford 428 Vs. Pontiac 428: Here's How The Engines Compare

Leading up to the peak of the muscle car era, automakers like Ford and Pontiac were locked in a battle of one-upmanship. While smaller, higher revving engines were popular among hot rodders, there was something special about the raw power of large displacement engines. The 428s from Pontiac and Ford were among the most powerful, ruling streets and drag strips alike from the late 1960s into the early 1970s.

Ford stuffed the 428 into its full-size, midsize, and pony cars of the era with availability in models such as the Galaxie, Torino, and Shelby GT500. Horsepower ratings, though not always accurate from the factory for a variety of reasons, indicate the Ford 428 has slightly less power than its Pontiac competitor. Pontiac models with the 428 include full-size cars such as the Catalina and Bonneville, the midsize Grand Prix, and some GTO and Firebird models, primarily as a dealer option.

At the height of muscle car popularity, it was common to see 428-equipped Ford and Pontiac cars lined up head-to-head at the local dragstrip, or cruising next to each other on the main drag through town.

Ford debuted its 428 in 1966 as part of its FE engine series, a descendant of Ford's unique but short lived Y-block engine. The early 428 was given a factory-rated 345 horsepower. 

The 428 Cobra Jet, as seen at the 1968 Winternationals drag race, became available for street cars the same year. While it was rated at 335 horsepower, Hot Rod recorded a 428CJ making 365.1 hp on the dyno and predicted it would climb to roughly 375 hp after break-in, and likely reach about 400 hp with headers. Ford discontinued the 428CJ in its midsize cars in 1970 and from the pony car lineup in 1971.

Pontiac introduced its 428 in the 1967 Bonneville (and other full-size Pontiacs) with two engine variants, the standard 360-hp model and the 376-hp High Output. Pontiac upped the ante in 1968, increasing the power from its 428 offerings to 375 and 390 horsepower. In 1969, the Bonneville's standard 428 was downgraded to 360 horsepower while the 1969 Grand Prix's standard 428 mill produced 370 hp. HO 428s with 390-hp were still available for select Pontiacs. 1969 was the final year for Pontiac's 428, it was replaced with the 455 for the 1970 model year.

While Ford and Pontiac took some creative license in the 1960s when branding their 428 cubic-inch engines, it's certainly not the most cringe-worthy car marketing you've ever seen. It's probably more accurately described as a little white lie. We might even call it a mistake if it weren't for the presumption that engine designers from both car companies knew the truth and would have provided the facts as a matter of course.

The secret is that neither the Ford nor Pontiac 428 actually displaced 428 cubic inches. At first you'll think we're nitpicking the facts and both automakers simply rounded the true displacement to a more palatable number. While that's likely the excuse they'd use if cornered, you'd think they would at least follow the accepted rules of rounding we were all taught in grade school.

The facts are that when calculating cubic inches (π * r² * height * 8 cylinders) using the Pontiac 428's published 4.12-inch bore and 4.0-inch stroke, we get 426.613 cubic inches. Ford's 428 is closer with its 4.132-inch bore and 3.984-inch stroke, coming out to 427.386. Following the rounding rules to the nearest whole cubic inch, both 428 engines are actually 427 cubic inches. 

Upon its debut, Ford already had a 427 (although it was actually a 426) and evidently didn't care to have another. Pontiac, coming in a year later, likely didn't want to introduce a 427 to compete with Ford's 428. Besides, how many car enthusiasts at the time were going to put pencil to paper and figure out it was all a lie?