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Volvo: Safety Beyond the Star RatingsWhy the Hemi is a Legendary Engine
Very few engines become legends. But the Chrysler Hemi V8 is certainly one thanks to three generations of high compression mayhem.
What Is a Hemi, Anyway?
You have seen it on the side of your favorite muscle cars and your brother-in-law’s RAM heavy duty. The Hemi badge proclaims power and carries not a little air of superiority. For the MOPAR faithful, the Hemi is revered and respected. But what exactly makes a Hemi engine special, anyway?
The name hemi refers to the design of a hemispherical cylinder head. This domed cylinder head is formed from half a sphere (or technically a little less than half). The shape allows for greater compression and higher output. The design necessitates a domed piston head to match and is limited to two valves per cylinder, positioned opposite each other for proper airflow. Because the two valves are positioned this way, the head needs to be wide to accommodate the complicated valve train, making the hemis especially wide engines.
The first hemispherical engine used in an automobile was the back in 1905 by Belgian carmaker Pipe. The hemi design was adopted by other early makes including Fiat, Alfa Romeo, Peugeot, and Duesenberg.
Chrysler first began experimenting with the hemi design during WWII. They developed a V16, the XIV-2220, for the P-47 Thunderbolt fighter plane, though the war ended before it was put into production. They also used the hemi design for the M47 Patton tank’s V12. A few years later, in 1948, Chrysler engineers John Platner and William Drinkard began working on a smaller V8 version for use in passenger cars.
Chrysler’s Heavy FirePower
The first Chrysler Hemi for passenger cars was the 331 cu.-in. “FirePower” V8. Not only was it their first hemispherical engine in a car, but it was also Chrysler’s first overhead valve V8. The new 331 Hemi V8 was first offered in the Chrysler Imperial (standard in the Imperial Crown) and Chrysler New Yorker starting in 1951. Initial output for the 331 Hemi was 180 horsepower and 312 lb.-ft. of torque, making the New Yorker quicker than an Olds 88 of the same vintage.
Tweaks and modifications to the engine steadily increased output, from 193 horsepower to 225 horse to 308 horse. The Hemi was added to the new Chrysler C-300 in 1955, which billed itself as the “world’s fastest stock car” when it competed in NASCAR starting that same year. The following year, the 300B, was given a new Hemi, the 354 cu.-in. FirePower V8, making up to 355 horsepower. The version of the 354 given to the Imperial and the New Yorker made a more modest 280 horsepower. That output rose again in 1957 to between up to 345 horsepower in the Imperial and New Yorker while the 300C and 300D could access a four-barrel version that made up to 375 horsepower.
The rest of the Chrysler family also made use of the hemispherical design. DeSoto made FireDome Hemi V8s ranging from 276 cu.-inches up to 345 cu.-inches. Dodge put Hemi V8s in their trucks like the C-Series and the D-501. The first generation of Hemi V8s ceased production after 1958.
The 426 and Classic Muscle
The Hemi, however, was far from dead. Starting in 1964, Chrysler brought back the design when they began work on a new NASCAR engine, the 426. First fielded in the ’64 Belvedere, the 426 Hemi was rated to 425 gross horsepower (at the wheels, output was closer to 325 horsepower). Without putting the new Hemi in road cars, Chrysler failed to meet homologation standards for the 1965 season. The following year, 1966, was therefore the beginning of something special as Chrysler shoved their new powerplant into production vehicles starting with the Dodge Coronet and Dodge Charger, and Plymouths Belvedere and Satellite. The next year, the Plymouth GTX got the Hemi treatment and, in 1968, the Dart, Barracuda, Super Bee, and Road Runner all got Hemi options. In 1969, the Charger Daytona was now Hemi powered the Superbird, Challenger, and Hemi Cuda following in 1970.
Like the rest of the muscle car segment, the Hemi fell victim to emissions and fuel economy regulations and was discontinued after 1971.
Rise of the Hellcat
It took another 30 years before Chrysler once again brought back the Hemi for a third go around. Starting in 2003, a new 5.7L Hemi V8 making 345 horsepower and 375 lb.-ft. of torque was available for the RAM 1500 pickup. The Dodge Durango was given a Hemi in 2004 and a year later the Magnum and Chrysler 300 joined in. The returning Dodge Charger got its Hemi as well in 2006, along with the Jeep Commander, Chrysler Aspen, and Dodge Challenger. Even the Jeep Wagoneer eventually got a Hemi in 2022.
The 5.7L Hemi was just the beginning, however. Following the old axiom of there being no replacement for displacement, Chrysler added volume to the Hemi for a 6.1L for the Magnum SRT-8, and Charger SRT-8, as well as the Chrysler 300 and Dodge Challenger, as well as a 6.4L version, aka the 392 Hemi for the usual suspects of the Challenger and Charger. Most significantly, the 392 Hemi is the only V8 available for the Jeep Wrangler.
Because the 425 horsepower from the 6.1L is not nearly enough nor even the 6.4L’s 470 horses, the folks at Dodge created the 6.2L supercharged Hellcat Hemi V8 with 707 horsepower. This monster engine is what powers the RAM 1500 TRX, Cherokee Trackhawk, Durango SRT Hellcat, and, of course, the Dodge Challenger and Dodge Charger SRT Hellcats.
A crate version of this supercharged 6.2L, the 426 Hellephant is sold by Dodge when nothing less than a full 1,000 horsepower will do the trick. (The Hellephant name combines the Hellcat with the original 426 Hemi’s nickname, “the elephant engine” for its size and weight.)
Dodge has been busy of late tuning their Hemis as part of their series of “Last Call” Dodge performance cars. The Last Call Dodges are a fitting tribute to the Hemi, one of the greatest, most powerful engines of all time (I can almost hear Tim Allen grunting in the distance as I type these words).
