5 Classic Muscle Car Engines That Made Tons Of Torque

Classic muscle cars were the pinnacle of U.S. automotive engineering of the time, with their massive big-block engines producing boatloads of horsepower and torque while still being affordable compared to sports cars. They are defined as American-made cars produced between 1964 and 1975, usually coupes or two-door sedans, that featured powerful and loud rear-wheel drive engines in a V8 configuration. Manufacturers famous for their muscle cars include all the big three — Chrysler, Ford, General Motors, under brands such as Buick, Chevrolet, Dodge, Mercury, Oldsmobile, Plymouth, Pontiac, and Shelby — as well as smaller manufacturers such as AMC.

By the standards of the time, these cars had the highest power and torque, but of course, compared to modern era cars with the multitude of engine design innovations since, classic muscle car figures may look a little tame. Here we list five of the most powerful classic muscle cars engines ever built, and we're concentrating on torque — the rotational force measured in pound-feet (lb-ft) or Newton meters (Nm) that's generated by an engine. It's a measure of how strong an engine is or how much work it can do, which translates into acceleration, speed, and pulling force.

While sports cars of today often produce in excess of 1,000 lb-ft of torque, classic muscle cars rarely exceeded 450 lb-ft. Some did however, and here we have five car engines all producing 500 lb-ft or more of torque, with one — the Buick Skylark GS455's V8 engine the record-holder for the era with 510 lb-ft of torque. While you may expect one of Ford's muscle car engines in this list, none of them from the era match up to the performance of those listed here. 

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Powering one of the most iconic muscle cars in history — the Chevrolet Chevelle SS — the 1970 Chevrolet 454 LS5 and LS6 engines produced an astonishing 500 lb-ft of torque. While the first Chevrolet Chevelle model launched in 1964, it reached its zenith in 1970 with the Chevrolet Chevelle SS 454. 1970 saw GM lift its self-imposed displacement ban on engines with over 400 cubic inches in mid-sized cars, leading to sudden introduction of big-block engines in all the company's popular brands, from Chevrolet to Buick, Oldsmobile, and Pontiac. Chevrolet decided to enlarge its 427 cubic inch engine to 454 cubic inches (7.4-liter V8).

The basic model, featuring the LS5 engine, produced 360 horsepower and 500 lb-ft of torque at 3,200 rpm. Only 4,298 units of the Chevelle SS 454 LS5 were ever made. The RPO (regular production option) Z15 SS option with the LS6 engine, coupled with a Holley four-barrel carburetor and a cowl induction hood, delivered 450 horsepower with the same 500 lb-ft of torque at 3,600 rpm. It's said to be the highest factory horsepower rating of the time. Only 4,475 LS6 Chevelle SS cars were ever produced.

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Just like with other GM-owned brands in this list, Pontiac celebrated the company's removal of its arbitrary displacement ban in 1970 with the introduction of a L75 D-port 455 cubic inch engine (7.5-liter V8) in its popular Pontiac GTO (Gran Turismo Omologato) model, under the 455 H.O. trim. While the engine only produced a somewhat modest 360 horsepower, it managed to deliver 500 lb-feet of torque at just 2,700 rpm.

The Pontiac GTO is considered the muscle car that re-popularized the segment with the introduction of the GTO option in 1964 for the Pontiac Tempest LeMans, which itself originated in 1961 as a trim upgrade for the Pontiac Tempest. It was also the first company to describe its car as a "muscle car," where the term is thought to have originated. Pontiac began offering the GTO as a separate line in 1966. The Pontiac GTO Judge package, first introduced in 1969 with a rear spoiler, wider tires, and Ram Air 400 engine, was named after a line "Here Comes the Judge" from a popular TV show at the time, "Laugh-In." It was an effort by Pontiac to increase sales of the GTO line. The 1970 Pontiac GTO 455 HO also got the Judge option, but only late in the year.

[Featured image by Michael Barera via Wikimedia Commons | Cropped and scaled | CC BY-SA 4.0]

Buick, like GM sister brands Pontiac and Chevrolet, commemorated the removal of the 400 cubic inch engine ban on mid-sized cars by using the 455 cubic inch engine (7.5-liter V8) in its Skylark muscle car — 1970 Buick Skylark GS 455. The Buick V8 engine in 1970 offered 350 horsepower and 510 lb-ft of torque at 2,800 rpm. This was the most torque of any American factory V8 muscle car engine, a record held for over 30 years until the second-generation Dodge Viper.

The Buick Skylark was introduced as a separate line for the first time in the brand's history in 1964, and in 1965, the company added a Gran Sport (GS) option, and then a Stage 1 performance option in 1969. The 1970 Buick Skylark GS455 had an even beefier Stage 1 option that produced 360 horsepower (a conservative estimate) but the same amount of torque. There was also GSX, replete with a spoiler, which also was available with the Stage 1 performance upgrade.

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The Oldsmobile brand from GM produced what was perhaps the first muscle car — the Oldsmobile Rocket 88 — in 1949. With such a heritage, it's hard not to include engines in this list from the brand, especially since its 455 cubic inch 7.5-liter Rocket V8 engine produced 390 horsepower at 5,000 rpm and 500 lb-ft of torque at 3,200 rpm. It was used in the 1968 and 1969 Oldsmobile Hurst/Old, which based its design on the Oldsmobile Cutlass and Oldsmobile 442. The company bypassed the GM ban on engines larger than 400 cubic inches on mid-sized cars by claiming Hurst installed the engines.

The company offered a similar engine in the 1970 Oldsmobile 442, and since it no longer had to hide its large engine from GM after the ban was lifted, so the Hurst/Olds tag was removed. It made the Rocket 455 V8 engine standard on the Oldsmobile 442, producing 365 horsepower and 500 lb-ft of torque. It also offered a W30 option with 370 horsepower and the same amount of torque.

Finally, we come to the last engine on the list, the 1973 Pontiac Super Duty 455 (SD 455), also called the 455 High Output, one of the most iconic engines of the classic muscle car era. It was one of the last engines of the classic muscle car era to offer 500 lb-ft, and one of the largest V8 engines offered in a passenger car. It offered 370 horsepower with up to 500 lb-ft of torque. The engine was offered in Pontiac Firebird Formula and the Pontiac Trans Am SD 455. It featured a stronger cylinder block than previous iterations, and its cylinder heads were designed with inspiration from the Pontiac Ram Air IV heads. However, the SD 455 engine was modifiable with a few tweaks all the way up to 550 horsepower.

Very few of these cars and engines were ever made, with only 43 1973 Pontiac Firebird Formula SD 455 units (only 10 units with 4-speed transmission) and 252 Pontiac Trans Am SD 455 units (only 72 with manual transmission).