10 Highest Horsepower Classic Muscle Cars Will Blow Your Mind

In an effort to improve top speed along the legendary Mulsanne Straight at the 24 Hours of Le Mans race, a number of enclosed, coupe variations were constructed. Six were constructed, each being subtly different from the rest. The result was a monster of a sports car, with 425 horsepower in a 2,300 pound car. For reference, that is 400 pounds lighter than a Miata, but 3 times the power. The Cobra won hundreds of races in the ‘60s, and became the car that every other supercar would be measured against, often even today.

Dealerships in the late ‘60s found a way around Chevy’s limit on high displacement engines and began ordering 427s fitted into the compact Camaro. Most of them were iron blocks, but a few dozen were hand-bilt aluminum 427s. These lightweight engines were a perfect match for any drag race car for it is a drag race ready, and only needed exhaust and tuning to cross the 500 horsepower mark.

1970 Plymouth Barracuda Hemi
The ‘cuda shed its economy car roots in 1970, modernizing its looks, handling, and capabilities for the ‘70s. The Plymouth Barracuda Hemi offered power from approximately 270 hp (200 kW) SAE net in the high performance 383-4V to approximately 355 hp (265 kW) SAE net in the 426-8V.

1970 was probably the most boosting time for the first muscle car era. For Chevy fans, the best of the best is a Chevelle with the LS-6 454 V8. Check one box on the order from, and you could get an estimated 450 horsepower in a spankin’ new box body that defined the muscle car era.

The Pontiac Trans Am SD455 weighed in at 3,850 lb (1,750 kg) in their first year of production. The 1974 models showed a more improved “shovel-nose” front end and new wide “slotted” taillights.  The SD-455 produced 290 hp (220 kW).

The Mustang kicked off the pony car class with its physical characteristic, not its horsepower. V8s and performance seemed to be an afterthought in 1964, but all of that had developed by ’69. Officially rated 335 hp, decades after the classic muscle car era, dynometers would show it was more like 410 hp. It’s the SD of Mustangs.

Acknowledged for their torquey engines, Buick stuffed plenty of 350s and 400s into their GS. In 1970, Buick dropped their own 455 into the GS. With 360 hp and a crushing 510 lb/ft, the GS455 held the record for most torque in a factory American engine, until the second gen Viper. Motor Trend tested the GS455 and ran a traction limited 13.4 at 106 mph.

Corvette showed further into the smog era than most, receiving its largest engine in 1971. While previous versions of the big block had been bold, like the L88 427, by ’71 you were able to get a 454 in two flavors. First was the LS5, with “only” 365 hp and 550 lb/ft. That is not a mistake. If you’re not contented, step up to the LS6, borrowed from the Chevelle and turned way up. For one year only, the LS6 made 425 hp and a ridiculous 575 lb/ft.

Dropping the 428 FE from the same quarter Thunderbird added a touch of eliteness to the big wedgey coupe. A four speed manual, heavy duty suspension, and power disc brakes, made this a NASCAR racer for the street. While it made 345 hp in stock trim, clever buyers could opt for muffler/resonator delete, leaving the exhaust with just factory installed high-flowing glasspacks.

1969 AMC AMX 390
An old little car company, the AMC. Never as big as the major American auto makers, AMC had to be resourceful and imaginative to survive. Their late entry to the muscle car wars was the compact hatchback AMX. Stuffing the big 390 V8 under the hood, this was a total burnout machine with 325 hp. In the optional – and loud – “The Machine” trim, the AMX made 340 hp, making it the most powerful AMC production engine. That may fall a bit short on this list, but remember that this was a 3,200 lb car with a manual trans, meaning this car is every bit the match of the thirty-years-newer LS1 Camaro.