What Is a Hemi?

With a storied background that includes NASCAR domination, demolished world records, and a series of generationally iconic muscle cars, Hemis are prized by all gearheads, wrench monkeys, and gasoline-swillers. But do you really know the history of the Hemi? It’s not what you think.

For most, the Hemi starts and stops with Chrysler. Dodge Chargers, Plymouth Barracudas, GTXs, and the modern cars with Hemi-based Hellcat engines in them, are all that they know and adore. That, however, is only a fraction of the Hemi story. In fact, the Hemi has been around for more than 100 years, dating back to the turn of the 20th century. 

Never fear, The Drive’s encyclopedic editors have pulled together a mega Hemi guide you never knew you needed! So sit down, strap in, hold on, and get ready for the full download on one of America’s most well-known engine designs! 

“Hemi” is the colloquial term for an engine with hemispherical combustion chambers, likely referring to Chrysler’s muscle cars in our modern automotive epoch. However, Chrysler isn’t the only manufacturer to have built “Hemi” engines, nor was it even the originator of the design. 

Sorry, muscle car fans, but the “Hemi” was invented by Allie Ray Welch out of Chelsea, Wisconsin around the turn of the last century, with the first prototype built by Truscott Launch and Engine Company.  A two-cylinder engine, the first Hemi ever was built for use in a boat! 

That first Allie Ray Welch engine was built in 1901. Neat!

As for the first Hemi-powered car, Chrysler wasn’t the first either, that honor went to a Belgian company called Pipe in 1905. After Pipe, Peugeot, Alfa Romeo, Daimler, and Riley began manufacturing “Hemi” engines, too, with Peugeot and Alfa Romeo dropping them into their respective Grand Prix racers. 

As for the engine design, it’s one that’s been used by almost every single manufacturer since, spanning makes including Alfa Romeo, Jaguar, Toyota, Porsche, Mitsubishi, Aston Martin, Lancia, Lotus, Mercedes-Benz, Chrysler, and even Ford. 

Everyone’s favorite muscle car manufacturer, Chrysler, didn’t get into the Hemi game until the Second World War, where it began developing an experimental V16 Hemi for use in the United States’ P-47 Thunderbolt. However, by the time the engine was ready for production, the war effort was winding down, and the engine was scrapped. 

Saving all that research and development, Chrysler decided to drop the Hemi technology into its road cars, with the first Chrysler vehicle to use hemispherical combustion chambers debuting in 1950 under the FirePower nameplate. 

FirePower would continue to be used for Chryslers and Imperials, while DeSoto dubbed its version FireDome, and Dodge used Red Ram. Plymouth didn’t get a naming convention until the Hemi nameplate, as we now know it, came about later. 

Hop in, muscle car nerds, we’re gonna get educated. 

Over Chrysler’s own history, the Hemi has gone through a multitude of variations, which bore, stroke, displacement, and even type of engine design varying from one year to the next. There’ve been inline engines, 6- and 8-cylinder engines, and the above experimental V16, too. 

“Hemi,” however, wasn’t dropped onto a car until the engine’s second generation. For that, the engine grew in size and displacement, putting out a whopping 7.0 liters and designed for use in NASCAR and the road-racing Plymouth Belvedere. NASCAR, however, outlawed the race engine by prescribing that Chrysler must produce road-going versions in order to compete. Chrysler’s street cars got a “Street Hemi” iteration soon after. 

It was during this time period that the Hemi nameplate as we know it today got its inception, with Dodge, Chrysler, and Plymouth all adopting Hemi engines for use in their respective legendary performance cars. Things like the Barracuda, Charger, Challenger, Satellite, Road Runner, Super Bee, Daytona, GTX, and Coronet. The biggest change to the Hemi, though, occurred when Chrysler resurfaced the nameplate back in 2003 for the Dodge RAM. 

Although a “Hemi” is currently offered across Fiat Chrysler’s model lineup, everything from trucks to SUVs and muscle cars, modern “Hemis” are Hemis in name only. As engine technology has advanced to where we are today, Fiat Chrysler changed the V8’s design to be both more powerful, reliable, and fuel-efficient, and thus removed what made a Hemi a Hemi, i.e. its signature hemispherical head. 

The new “Hemi” design would go on to power a number of Chrysler’s most recognizable models, including the new Challenger, Charger, Grand Cherokee, Aspen, and Durango. This has culminated with the “Hellephant,” a 1,000 horsepower, supercharged V8. 

Fiat Chrysler, soon to become Stellantis, knows you all love horsepower. That’s why the company offers such a breath of Hemi-powered muscle cars, SUVs, and whatever Jeep people call Jeeps. 

The newly announced Wrangler Rubicon 392 is the first Wrangler to feature a V8 in a very long time. It will be on sale sometime next year. 

Price: Not yet announced.

Horsepower: 470

The Jeep Grand Cherokee comes in a few flavors of Hemi adornment, including a standard Hemi and a supercharged iteration. 

Price: $69,145-$87,895, including destination charges and fees?

Horsepower: 475-707

The Charger has changed greatly since its introduction in the 1960s, the biggest difference being the number of doors. And like the Grand Cherokee, the Charger now comes in a few flavors. 

Price: $36,495-$72,095

Horsepower: 370-797

You guessed it, you have a multitude of options when selecting a Hemi-powered Challenger, too.

Price: $34,995-$78,695

Horsepower: 375-797

The Durango is offered in three Hemi versions, the first with 360 horsepower, the middle with 475, and the ultimate with 710 horsepower. 

Price: $44,395-$$82,490

Horsepower: 360-710

The littlest RAM, if you can even call it that anymore, gets a few iterations of the Hemi, including a hybridized version and a supercharged one in the new TRX. 

Horsepower: 395-702

RAM’s heavy-duty trucks get Hemis too!

Horsepower: 410

The Hemi’s racing history spans almost the entirety of its life, with Peugeot and Alfa Romeo competing in Formula 1 with Hemi engines, along with Plymouth’s road racing efforts, Dodge’s NASCAR efforts, to consumer-spec drag racing, and pro-level Top Fuel and Funny Car drags. 

One of the most interesting racing tidbits is how Dodge’s NASCAR efforts saw the Hemi banned one year, only to return the following after a creative workaround. 

In NASCAR’s 1964 season, using the then-new Hemi race engine, Dodge was practically unstoppable. So much so, that at the Daytona 500, Richard Petty lapped the entire field and won the race. And both those drivers who claimed second and third were also using Hemi-powered cars, too. The season was so dominated by the Hemi cars that NASCAR instituted a rule that made street homologation a necessity for any racecar fielded for the following season. 

So what did Dodge do? It certainly didn’t want its winning streak stopped, so it began producing Street Hemis and took the Hemi cars racing again in 1966. Which Petty once again took to Daytona and subsequently won. So without the Hemi’s NASCAR domination, we’d never have the Hellcats, Demons, and every other Hemi-powered muscle car we all enjoy today. 

Learning your car’s behavior, quirks, and personality can be done on your own, but you’re not exactly doing so in a vacuum. A missed braking point or target fixating on that tree over there could mean a bent bumper or some serious medical bills. Why take the chance when you can learn safely how to drive your Hemi from the professionals at Skip Barber Race Car Driving School?

The Drive has partnered with Skip Barber, the legendary racing school, to ensure that when you first prime your Hemi’s ignition, you won’t fly off into a ditch. 

You’ve got questions, The Drive has answers!

A. Did you not read the above?

A. The main reason Hemis are so venerated is because of its history on the road, in racing, and even in aviation. And the ones everyone wants, those from the 1970s, were extremely rare. Chrysler produced only 11,000 Hemi engines.

A. A combination of factors, including the combustion chamber design, the bore and stroke, and the pressure the engine’s internal components are able to withstand. 

A. Because engine technology has advanced and there are better, more fuel-efficient ways to make gobs of horsepower, i.e. the Hellcats.

A. No. 

A. Money?

You know you want more Hemi facts!

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