It’s 4-26! Yep, It’s Hemi® Day!!!

Three Numbers to Rule the Track

Stand up and cheer, its April 26, which makes today HEMI® DAY!!! HEMI DAY!!! HEMI DAY!!! As you fist pump and celebrate the mighty Mopar® 426 HEMI, the most potent muscle car engine of the supercar sixties, shout the names of The Greats…Tom Hoover! The Ramchargers! The Golden Commandos! Don Garlits! Dick Landy! Sox & Martin! Herb McCandless! Bill “Maverick” Golden! Don Prudhomme! Your hometown HEMI hero (every town had one)! The list goes on and on.

Yes, on this 26th day of the 4th month of the year, let’s celebrate the mighty 426 HEMI. In both Race and Street form, no other engine in company history was as successful at beating the competition, attracting consumer interest and revitalizing the Dodge brand as the mighty 4-2-6.

First offered in 1964 and ’65 as a limited production engine meant strictly for sanctioned competition (the Race HEMI, 742 built – includes 150 1968 HEMI A-bodies with cross ram), then from 1966 to ’71 as a $900 option aboard top-tier Dodge and Plymouth muscle cars (the Street HEMI, 9,955 built), the trickle-down halo effect of the HEMI’s magic on the entire Dodge product lineup cannot be overstated.

It began the day after HEMI-powered Plymouth and Dodge vehicles dominated the 1964 NASCAR Daytona 500 in February of 1964. Totally new and unproven in competition, HEMIs came in first, second and third, and the winning car (Richard Petty’s #43 Plymouth) led the 46-car field for 183 of the race’s 200 laps. A full 7 mph faster than the closest competition, HEMIs introduced NASCAR spectators to the era of 170-plus mph average lap speeds.

Proving the “win on Sunday, sell on Monday” ethos, Dodge and Chrysler-Plymouth dealerships all across the country were flooded with customers seeking a piece of the glory. Even if they bought a Slant Six Dart or a 383 Polara, they – and everyone else on the road – associated that new Dodge with the victorious racers they’d seen on TV just days before.

So what is it about the 426 HEMI that makes it so magical, so omnipotent? The answer, in a word, is breathing. A gas-burning reciprocating internal combustion engine is essentially an air pump that traps expanding air momentarily to push down on pistons that turn a crankshaft. The rotating crankshaft is coupled to the transmission and rear tires to send the car around the track – or down the road.

The HEMI’s ability to breathe more efficiently than other engines results from cylinder heads designed with large intake and exhaust ports and valves that enter and exit the combustion chamber in a straight line. Competing cylinder head designs suffered from ports with twists and turns that reduced breathing ability. The HEMI is so effective, a certain Dearborn, Michigan, based carmaker paid tribute in the form of not one, but two HEMI-type V8 engine types by the end of the 1960s (the Single Over Head Cam 427 and Boss 429).

As for the name, Chrysler engine designers found that the most efficient way to package the straight-shot ports was to have them enter and exit a dome-like combustion chamber. Resembling the inside of a softball that’s been sliced in half (and about the same size), Chrysler advertising and marketing teams seized on the hemispherical combustion chambers and named the engine after them. But was the 426 HEMI of 1964 the first of its kind?

Younger people forget the fact that the 426 HEMI was not Chrysler Corp.’s first HEMI engine campaign. In fact, during the 1950s, Chrysler (1951-’58 Firepower), DeSoto (1952-’57 Firedome) and Dodge (1953-’57 Red Ram) all offered HEMI-type engines by the hundreds of thousands that were installed in regular passenger cars for daily driving with plenty of punch. These first-generation HEMIs were marketed as being less dependent on high-octane gasoline than competing post-WWII V8 engine types. These Chrysler (331-, 354- and 392-cubic-inch), DeSoto (276-, 291-, 330-, 341- and 345-cubic-inch) and Dodge (241-, 270-, 315- and 325-cubic-inch) HEMIs are a success story unto themselves and were quickly embraced by drag racers. But this is 4-26, so let’s get back to the matter at hand.

Okay, we now know that hemispherical combustion chambers give the HEMI its name, but what about that magical number, 4-2-6? For the answer, we have to remember that most professional auto racing around the globe is governed by sanctioning bodies that provide vital organization and (often controversial) rules. In drag racing, the National Hot Rod Association (NHRA) is king and the National Association for Stock Car Automobile Racing (NASCAR) reigns over most full-body stock car race events.

Both sanctioning bodies were formed in the immediate post-WWII time frame and, by 1964, were “well-oiled machines”. Each was doing a fine job of assuring professionally run, national-scale events for racers and fans alike. Part of the process involved maintaining a level playing field to prevent one make of car from dominating and turning races into predictable, one-sided events. At the dawn of the 1960s, as Detroit automobiles were growing bigger and heavier, their engines grew to keep pace. The first wave of so-called “big block” V8 engines had arrived.

The biggest engines generally maxed out at around 400 cubic inches at the time, or, in metric terms, roughly 6.6 liters (61 cubic inches equals approximately 1 liter, 1 liter equals 1,000 cc). So when, in 1961, NASCAR established a maximum cubic inch limit to keep race teams on similar footing, they chose 7 liters, or 427 cubes as the ceiling. At the time, 427 cubes was considered gargantuan and only Lincoln-Mercury’s luxury-oriented 430 cube V8 engine was bigger.

The rest of the big guns for 1961 measured 389 (Pontiac), 390 (Ford), 409 (Chevy) and 413 (Chrysler) cubic inches. With its 427-cubic-inch limit, NASCAR assumed they’d left plenty of cushion for future growth. But with racers being racers, seeking to take full advantage of the rule book, each car maker quickly “inched up” to the 7-liter limit. The 389 grew to 421, the 390 grew to 406 and then 427 cubes, the 409 went to 427 (the 1963 Z11) and Mopar’s 413 wedge expanded to 426 in 1963. At the same time, the NHRA embraced the 7-liter displacement limit for its top stock and super stock drag race categories, so when Chrysler re-embraced hemispherical combustion chamber architecture in 1964, the displacement was set just one cube below the NASCAR and NHRA legal maximum, and the 426 HEMI was born.

So, that’s the story of how the 426 HEMI got its name, displacement – and why we celebrate HEMI Day on 4-26 of every year. The best part of the HEMI story is how Mopar Performance Parts has revived the 426 HEMI as a pre-assembled crate engine you can buy right now. Better still, without a strict NASCAR or NHRA rule book to keep a lid on cylinder displacement, the Mopar Performance mavens were free to add stroker cranks. So in addition to the old faithful 4-2-6, you can buy HEMI crate engines with 472, 528 and even 572 cubic inches.

Since its 1998 launch, the Mopar Performance Parts HEMI crate engine program has been a huge success, with thousands of brand-new HEMI engines powering Mopar restorations, racecars and hot rods all over the globe. You read that right, as of this writing in 2018, brand-new HEMI crate engines have been available for 20 years. By comparison, the original 426 HEMI program only ran for 8 years (1964-’71). Such is the power of the HEMI’s legend, this second go-round has lasted over twice as long as the original, and there’s no end in sight. Are these the good old days? You better believe it!

But as cool as the retro crate HEMI program is, let’s not forget the astonishing fact that HEMIs are not quaint museum pieces from days gone by. Those free-flowing ports and octane-indifferent hemispherical combustion chambers have been part of the new third-generation HEMI family since 2003. The year 2018 marks the sixteenth anniversary of the third-generation 5.7, 6.1, 6.2 and 6.4 liter HEMI V8 family found in Ram trucks and reborn legends like the Dodge Charger and Challenger. These free-breathing V8 engines all feature the same laterally opposed intake and exhaust port configuration that makes the 426 HEMI so potent. They’ve also got the same double rocker shaft layout to suit the placement of the valve stems atop the hemispherical combustion chamber. Far from some hollow marketing-driven, close-but-no-cigar re-boot, the new HEMIs are true evolutions of their first- and second-generation forebears.

Going back to 1984, when your author was a 20-year-old college sophomore, the then-new Dodge Shelby Charger 2.2 TV and magazine ads touted standing start acceleration in a seemingly respectable 5.5 seconds and NHRA certified quarter-mile runs in the sub-16 second bracket. But a close look at the fine print revealed that the 5.5-second sprint was of the zero-to-fifty mph variety, not the industry standard 0-60. The cars were certainly the right products for the times and sold quite well, but with front wheel drive and a mere 110 horsepower, they were a far cry from the 1964 426 HEMI that launched just 20 years before. And I knew it. Things seemed pretty bleak for the future of high-performance driving.

Back then, I would have bet just about anything we’d never see the likes of today’s Hellcat or Dodge Challenger SRT® Demon. The SRT Demon is so quick in the quarter-mile, the NHRA banished it until owners install a certified roll cage, a fact Dodge celebrates in full-page magazine ads (see the “Sorry. Not Sorry” campaign). If you told me I’d live to see a day of reborn Challengers and Chargers with retro styling, the return of the Scat Pack, Shaker hood scoops, the new HEMI engine program and showroom stock Challengers that are too fast for the NHRA, I’d have said you were nuts.

But here we are. The glorious evidence is all around us every day in traffic. Didja know that Dodge has built nearly twice as many new (2008-’18) Challengers as the “classic” original of 1970-’74? And sales keep going! As for HEMI production, there have been more third-generation 5.7-6.4s built than all first-generation (1951-’58) and second-generation (1964-’71) HEMIs combined! And if you can’t wait until next April 26th to celebrate HEMI Day again, remember that each day those magical numbers “4-2-6” are displayed on every digital clock face twice. I get a little thrill any time I glance at the clock and its 4:26 – a.m. or p.m., it makes no difference. Those numbers always make me smile. The good old days are right now.

Celebrate Dodge 426 HEMI Day any day of the year.  Order the newest t-shirt proudly displaying the power of 426 HEMI performance today!