426 Hemi: Mopar Monster

426 Hemi: Mopar Monster


Is there any word in the automotive lexicon that conjures up more absurd imagery? Tire smoke that chokes out your logic and the General Lee runnin’ from the Sheriff are just some of the things that you think of when you hear “Hemi”.

Although the Hemi (short for Hemispherical) engine has been around in one way or another since World War II, its real popularity and legendary status came from the Muscle Car wars of the 1960s. A time when engines couldn’t be big enough and horsepower was a floating number that was meant to keep the insurance companies happy, but those who drove those monsters of the day knew they were putting down way more power than the spec sheet. Among the most legendary motors of that period was the 426 Hemi, a 7.0-liter monster that was so big, and so expensive that only 11,000 ever made their way into a Chrysler Group vehicle.

We’re going to tell you everything about this incredible motor and what led up to its legendary status:

Ready to dive into what makes a Hemi so amazing? Let’s get into it!

Hemi History

We don’t want to bore you with science, but in order to understand why the Hemi is so great, we need to delve a bit into the unique design of this motor. All internal combustion engines (non - diesel) use a combination of air, fuel, and spark to create an explosion in the combustion chamber of the engine.

In a Hemi engine, the combustion chamber has a hemispherical shape (think half the Earth or Northern / Southern Hemispheres) vs. a triangle-shaped design typically found on passenger cars of the day. Chrysler engineers believed (correctly) that the increased surface area inside the chamber would produce a more efficient and more powerful burn. Great! Right? Well, not so fast because of packaging issues with valves and rocker assemblies, the mighty Hemi was limited to 2 valves per cylinder but for a while, that didn’t really matter.

Aircraft Roots

Believe it or not, the first application of the Hemi chamber on an engine was an experimental aircraft engine known as the XIV-2220, which was destined for the P-47 Thunderbolt as an upgrade to the venerable Pratt & Whitney powerplant. This incredible engine was an inverted V16 design that put out a staggering 2,500 horsepower, utilized advanced alloys, and had hemispherical chambers. Although it never went into production (due to the end of World War II) it gave Chrysler engineers an opportunity to work and experiment with this unique style of engine.

FirePower, Power Dome, Red Dome … etc.

Fresh off the end of the War, Chrysler immediately took what they learned from the XIV aircraft engine and developed a Hemi engine for their passenger cars. Dropping in 1950 as a 1951 model, the first Hemi V-8 was originally known as the FirePower, and displaced a solid 331 cubic inches, and made a stout 180 horsepower. Eventually, every Chrysler division had a version of the FirePower V-8 under different trade names such as Power Dome, and Red Dome.

Various versions of the FirePower V-8 were released from 1951 - 1959, culminating with the 392 that powered Chrysler legends like the 300C and could make up to 390 horsepower in certain

Chrysler would abandon the Hemi design for a few years but its return would mark the swan song for the Hemi: The 426.

Muscle Car Wars

Starting in 1964, the 426 Hemi (now trademarked by Chrysler) made its debut but not quite in the way you may think. Its introduction was not on the street but on the NASCAR circuit in the 1964 Plymouth Belvedere. Here, the crafty folks over at Chrysler really managed to pull one over on the people of Nascar, but also on their competitors because the 426 was not available to the buying public.

This blatantly skirted the rules, and Ford complained about the Belvedere (which was dominating) which forced NASCAR to instill strict rules. Homologation was put into place, and the rules at the time stated that Chrysler has to sell 2,000 426 Hemi equipped Belvederes to compete in NASCAR. This forced them out of the 1965 season but for 1966, several versions of the Belvedere, and Coronet were available with the 426, as well as aluminum fenders/bumpers that were specifically built for drag racing.

They were back in business and they dominated.

The Elephant

Remember, beyond the popularity of NHRA and NASCAR, the mid-’60s saw America right smack in the middle of the muscle car wars. Once the Mustang hit the street, it was a lights-out rush to create engines with more and more horsepower.

The street version of the 426 earned the nickname of “The Elephant” because of its massive size and over-the-top dimensions. This thing was huge (800 + pounds)! In order to achieve the horsepower and torque figures of an engine that could compete in NASCAR without breaking the rules (OHV engines ONLY), the Hemi needed to make power without relying on overhead cam designs, or multi-valve layouts. In order to achieve this, the Hemi was designed with a slanted valve that allowed for a much larger valve design. Bigger valves equal better breathing and better breathing means more power! Additionally, the 426 also utilized an oversquare design with a bore x stroke of 4+1⁄4 in × 3+3⁄4 in (108.0 mm × 95.3 mm) that was optimal for high-rpm breathing.

1965 - 1971: 6 Years Of 426 Glory

This incredible motor was found in a wide variety of Chrysler products from 1965 - 1971, with the most notable (and most valuable) installation of the 426 Hemi belonging to the Barracuda, Charger, and Superbird.

Much like the rest of the muscle car era, the 426 quickly died with the oil embargo and the invention of strict emissions standards right at the beginning of 1971.

Here’s the whole list of vehicles where this incredible engine was installed:

  • 1966–1970 Dodge Coronet/Plymouth Belvedere
  • 1966–1971 Plymouth Satellite
  • 1966–1971 Dodge Charger
  • 1967–1971 Plymouth GTX
  • 1968 Dodge Dart Super Stock
  • 1968 Plymouth Barracuda
  • 1968–1971 Dodge Super Bee
  • 1968–1971 Plymouth Road Runner
  • 1969 Dodge Charger R/T
  • 1969 Dodge Charger Daytona
  • 1970 Plymouth Superbird
  • 1970–1971 Plymouth Hemi 'Cuda
  • 1970–1971 Dodge Challenger

Legacy & Today

Since only 11,000 426 Hemi engines made their way into Chrysler / Dodge / Plymouth products in the 1960s, and early 70s; today, they are exceedingly rare and very, very valuable. Don’t believe us? Just take a look at this amazing 426 Barracuda Convertible that recently sold at Mecum auctions for $3.5 million dollars. Yes, $3.5 million! Not only are vehicles from this era exceedingly valuable but they also laid the foundation for the re-launch of the Hemi engine in 2003. Without the fanfare of the original Hemi 426, fans wouldn’t have been foaming at the mouth for a new Hemi in the new millennium.

2018 Dodge Challenger Demon SRT

Anyone who follows the automotive world today knows that the muscle car war of the 1960s is having a resurgence today in the form of such insane creations as the 700+ horsepower Dodge Hellcat and Dodge Demon. These motors (although called Hemi) aren’t technically hemispherical chambers, and also utilize forced induction to create their crazy horsepower but the lore of the word Hemi, and the spirit of creating boundary-crushing creations is the same as it was way back in the swinging ’60s.

There’s a rare sense of childlike mischief and incredible engineering that goes into everything that Dodge does. The machines they create today are a perfect example of why American-made iron is so unique in this tumultuous world. Rather than play by the rules, Dodge / Chrysler chose to do things their own damn way. The right way.

Iconic. Proud. Legendary.

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