Last Updated: April, 2022

When it comes to big-block domestic power plants, the legendary 426 Hemi* has gained a permanent place in automobile history, but the 426 wasn’t Chrysler’s first hemispherical cylinder-head designed engine.  They, also, never intended to produce the engine for street use.  However, because of the muscle car wars of the ‘60s, as well as NASCAR’s rules, Chrysler decided to build cars like the Hemi-powered Road Runners, Cudas, Challengers, and Chargers.

Even today, the Hemi is a popular choice of hot rodders, not only for Mopar builds, but other non-Mopar brands, as well. For example, if you lift the hood of many custom builds, such as the early ‘40s Willys street rods, you’ll probably find a Hemi shoehorned in the engine bay. So, why was the Hemi so popular and how did it become a legend in its own right? It all started in 1964 at the Daytona 500, and continued on the streets across the country for nearly a decade. Although stories of the motor may have been embellished over the years, there’s no denying that Hemi-powered Mopars were hard to beat.

 

 

Yeah, It’s Got a Hemi

The secret to the 426 Hemi’s impressive performance was primarily because of its special hemispherical engine heads. The Hemi’s spark plug was located in the top center of the dome-shaped chamber, which shortened the flame travel and burn distance. This resulted in the air fuel mixture igniting more effectively.  Additionally, the inlet and outlet valves were positioned on each side of the spark plug, which improved the flow of gases in and out of the combustion chamber. These design features attributed to increased horsepower, when compared to other equally-sized engine displacements. Although the Chrysler Corporation didn’t invent the domed combustion chamber, they did perfect it, and made it affordable for production vehicles.

 

 

Win on Sunday, Sell on Monday

The old adage, “Win on Sunday, Sell on Monday” was a fundamental sales strategy involving NASCAR for a long time. Leading up to the 1964 season, Chrysler management decided they wanted to grab the “Win on Sunday” slogan for Mopar. Therefore, Chrysler gave the green light to build an all-out race engine to beat the competition in front of the huge NASCAR audience. Working right up to the start of the premier event on the NASCAR calendar, the Daytona 500, the new Hemi 426 was perfected, tested, and went on to win the top three spots in the race. In what would become the first in a string of wins for the year, “The King”, Richard Petty, took first place, driving the iconic #43 car, a 1964 Plymouth Belvedere. True to form, the following week Plymouth’s showroom traffic increased substantially. It seemed everyone wanted the Plymouth Richard Petty was driving.

 

The Street Hemi Arrives

In 1966, Chrysler began offering the engines in their production cars.  The “Street Hemi,” as it came to be known, had arrived!  Allpar.com estimates that 10,904 Hemi power plants were installed during the six years the engine option was available.   While Muscle Cars were the prime target for the Hemi, some 4-door sedans, and even a few station wagons, received this ultimate power option.  After all, what better way to tow a trailer than with an “Elephant Head” motor, as the Hemi was sometimes called because of its large cylinder heads.

Hemi Winged Warriors

A major chapter in the 426 Hemi story involved the famous Dodge and Plymouth “winged cars.”  In the late ‘60s, Ford and Mercury dominated the winner’s circle with their strong-running, aerodynamically-superior cars.  It wasn’t until late 1969, that Mopar made their presence known again by outfitting their drivers in the Hemi-powered Dodge Daytona.  This car was purposely designed for high speed oval track racing, regardless of how impractical they were for street use.  Then, in 1970 Plymouth debuted its Superbird, another “Winged Warrior” that also proved to be extremely aerodynamically suited to NASCAR racing.   Chrysler’s decision to use the Hemi in their winged cars enabled Bobby Isaac to win the NASCAR 1970 Grand National Championship in a Dodge Daytona, while the Plymouth Superbird also racked up numerous wins for the season. The winged cars also set speed records at Talladega (over 200mph) and at the Bonneville Salt Flats.

 

Hemi Power in a Straight Line

The 426 Hemi may have initially been developed for NASCAR, but it also became a winner in drag racing.  In 1964, the legendary drag racers, Ramchargers, began using the then-new Hemi in their altered wheelbase Dodge.  In the late 60’s, the famous factory-built Hemi Dodge Darts ruled the drag strip.   Later, Mopar Hemis, such as the Hot Wheel cars and the Sox and Martin Hemi Cuda, drew spectators and continued to grow the mystique of this engine.   In this same time period, one of the major players in the drag racing industry, Hurst, sponsored a famous show car, called “Hemi Under Glass.”**   The engine was mounted in the rear of the car, which enabled it do wheel stands down the full length of the drag strip.  Without a doubt, anyone who saw the car in action, either live or in photographs or videos, wouldn’t soon forget it was Hemi-powered.

 

 

The Last Hemi

The production of the 426 Street Hemi officially ended in early 1971, a victim of gasoline shortages and the automobile industry’s move to more fuel-efficient cars. However, despite Chrysler’s announcement, that summer a buyer ordered a Hemi Charger, hoping they still could get the engine. As it turned out, the car was built on June 18th, 1971, as ordered, making it the last documented 426 Street Hemi. 

 

 

Hemis – The Big Dollar Mopars

Collector car prices today are generally based on the rarity of the car and the nostalgic value associated with it. That’s why original 426 Hemi vehicles, and even Hemi transplant builds, are more highly coveted than their unequally-equipped counterparts. Although years of winning oval and drag strip racing, alone, were enough to boost Hemi’s celebrity status, limited production of Hemi-powered cars, such as the Dodge Daytona, Plymouth Superbird, and any type of convertible has made the Hemi even more valuable.

Here’s a sample of some of the rarest 426 Street Hemis that have crossed the auction block in recent years. If you’re wondering which Mopars are the most expensive, at well over $1 million, it’s obvious the Cuda and Challenger convertibles are the most desirable collectibles. For example, a blue 4-speed, Hemi Cuda convertible sold in 2014 for a staggering $3,500,000.

* Chrysler Corporation’s involvement with hemispherical engine design dates back to WWII, during their aircraft engine development. Using this experience, the company began offering high performance Hemi head engines in 1951, ranging in displacements of 301 to 392 CID. Depending on the vehicle model, this first generation Hemi engine was named “Red Ram,” “Firedome,” or “Firepower” (Dodge, DeSoto, Chrysler). The first generation Hemi was produced through 1958. Starting in 1966 and continuing through 1971, Chrysler offered the 426 “Street Hemi” (as opposed to their 426 racing Hemi), in production cars.

** “Hemi Under Glass,” a star attraction at many major drag strip events across the country BITD, was used to not only promote the sponsor Hurst, but also to the Hemi brand.

*** Hammer price is the price established by the highest bidder and acknowledged by the auctioneer before dropping the hammer or gavel (i.e., the price you hear the auctioneer call out when the vehicle is sold). Typically auction companies add a 10% or more sales commission to the hammer price (hammer price + commission = total price paid by buyer).