HEMI Engines

HEMI Engines 101: A Motorhead’s Favorite

There’s a lot of engine types and variations out there—diesel, gas, inline, turbo. No matter what engine makes it onto your best of list, just about every motorhead out there can make room for a HEMI.

What makes the HEMI such a special engine? Automotive Training Center decided to help you find out. Check out our introductory post on HEMI engines.

HEMI Engines 101: A Motorhead’s FavoriteWhat’s a HEMI?

From rugged Ram trucks to muscle cars that muster more power, HEMI engines have become synonymous with vehicles that release unrelenting power.

HEMI Chamber Shape: Aside from an indicator of major horses under the hood, more technically speaking, a HEMI motor is an engine that features a combustion chamber with a hemispherical cylinder head (hence HEMI).

Smaller Surface Area: In comparison to a traditional engine that features a flat-head chamber, a domed cylinder head can ramp up the power produced during the combustion process: With a curved head design that has a smaller surface area, heat is more easily trapped and contained within the chamber. More heat, more compression, more power.

Larger Valves: Aside from these advanced heat-trapping abilities, how HEMI engines position their valves (located on opposite sides of the chamber) provides another major power advantage. With more room in the intake valves, more air can filter into the combustion chamber to produce more power.

First HEMI as We Know It

When Chrysler created and trademarked its first-ever HEMI-headed V8 series in 1951, they ushered in an engine design phenomenon that would change the shape of true motor power for many years to come.

So what did the first HEMI look like? It was the 5.4-liter Chrysler FirePower engine that produced 180 horsepower (impressive at the time) and used a two-barrel carburetor.

Installed first on the Chrysler New Yorker, Chrysler Imperial, and Chrysler C-300A, the FirePower engine set off what’s today endearingly referred to as the “horsepower wars,” a time in which the pressure was on Dodge and Ford to catch up to Chrysler in their race for the title of muscle car with the most power.

The HEMI Today

HemiAs with many advancements in the auto industry, that first HEMI version was just the beginning. Fast-forward 60 years and today’s HEMI engines have come a long way from the Chrysler FirePower.

HEMIs can still be found under the hoods of some majorly powerful rides, versions that took the wisest parts of the 1950s HEMI design and worked out the kinks (some of which can surge up to and exceed 400 horsepower).

The evolution of the HEMI also spurred a new combustion chamber setup that was even more efficient in operation called the pentroof combustion chamber. Virtually identical to a HEMI, but with a pentagonal cylinder head, pentroof combustion chambers allow an engine to have three, four, or even five valves per cylinder instead of the HEMI’s two-valve limit.

Keep Up with the Latest in Car Tech

From what’s under the hood to what’s at the dashboard, the cars of today are fascinating feats of technology.

Want a peek at some of the industry’s most recent new models that are yet to be released? Head over to our post on all-new 2017-year vehicles that are coming out soon.


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