It’s truly a testament to Chrysler’s marketing team that the nickname “Hemi” is so completely associated with Mopar products. Merely uttering the term recalls muscle cars with eye-searing paint jobs, thundering V-8s and the pungent smell of roasting tires. However, many forget that hemispherical combustion chambers, where the term “Hemi” comes from, are not exclusive to Chrysler. Indeed, they’ve been around since early in the last century.
Why are hemis so popular? Because they the maximize the ratio of cylinder volume to surface area, which reduces heat loss and produces more power than a flat-headed cylinder design. The drawback is that compression ratio suffers and, at normal RPM ranges, combustion tends to be incomplete. Basically, they’re great for racing; not so much for commuting. Which is why the following five great hemis—not made by Chrysler—were all used in sports/racing cars:
Honey, I shrunk the Hemi. This 2.5-liter, micro V-8 hails from the land of tea and Triumphs. Conceived by famed motorcycle engineer Edward Turner, the little Daimler incorporates traits from a number of British bikes—most importantly, the aluminum hemi-headed design. Although tiny by American eight-cylinder standards, the engine was the perfect size for Daimler’s new sports car, the SP250. Despite the inherent displacement disadvantage, the engine more than makes up for it with its sound—essentially a lion’s roar coming out of a kitten. Hearing the tiny beast will have you asking yourself, “Where did that come from?”
It could be said that Porsches are the antithesis of American V-8 brutality. In the 1960s the U.S. was focusing on lower, longer, wider and more powerful cars, but across the Atlantic, the Germans had a different philosophy. Their priorities centered around balance and finesse, requiring a rear-mounted flat-6 engine in a lightweight shell. However, a tear-down of an earlier 160-hp 2.0-liter air-cooled power plant will reveal finned heads with a half-globe chamber. As it turns out, Stuttgart was very serious about making power as well—just in a smaller package. Perhaps we’re not so different after all.
Aston Martin V8
The closest James Bond ever came to Hemi power was a thrilling, two-wheeled chase sequence in a red ‘71 Mustang Mach 1, right? Well, no. It may be hard to believe, but Bond’s vehicle of choice in The Living Daylights, an Aston Martin V8 Vantage, featured the half-dome cylinder head design. As a matter of fact, all eight-cylinder Astons from the early ‘60s through the ‘80s were hemis, peaking with the 320-hp 5.3-liter version in the 1972 DBS V8.
Jaguar XK Inline-6
Despite its extensive race history, Chrysler has never taken the overall win at the 24 Hours of LeMans. But a hemi has. The world's greatest sports car race was won by none other than Jaguar and its aircraft-sleek D-type three years in a row: 1955, 1956 and 1957. Jaguar not only required top-notch aerodynamics, but also serious horsepower to fly down the Mulsanne Straight. The race car featured the now-famous XK series inline-6, propelling it to a then-blistering 172 mph top speed. As you can probably guess, below the twin cams sit 12 massive valves and six chambers sporting the dimensions of a baseball split in half. Similar to Chrysler’s Hemi, road-going versions of this engine also benefitted from their triumphant racing heritage—all XK motors produced in its 43 year run shared the hemi design. Sounds like the Brits were aware of the adage “race on Sunday, sell on Monday,” too.
Alfa Romeo Busso V-6
Long before the Italo-American merger between Fiat and Chrysler, the two companies were independently developing culture-shaking powerhouses. In Fiat’s case, no Italian engine this side of Ferrari comes close to the impact of Alfa Romeo’s immortal V-6, designed by Giuseppe Busso. The original 2.5-liter two-valve version, known now simply as “The Busso,” has one of the most distinctive exhaust notes of any six-cylinder ever produced. Not only that, but it also possesses looks to match—it’s rare to find an intake manifold design that puts Ford’s SHO to shame. Two iconic companies, two groundbreaking engines and one incredible cylinder head design. It’s the best U.S./Italian mash-up since Chicago-style pizza.
Honorable Mention: Ford Boss 429
Ford’s 1969 Boss 429 may not be a fully-fledged hemispherical design, but it was close enough to earn the title of “semi-hemi.” The massive engine was a direct response to Chrysler’s Elephant Engine (the 426-cid Hemi) and a follow up to the NASCAR-banned 427 SOHC. A quick look at the underside of its hulking cylinder head shows the shallow hemispherical design, barely disqualifying it from the category. Regardless, its big power and stump-pulling torque made the Boss Nine a force both on and off the super-speedway.
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