What is a Hemi Engine
Does that thing have a HEMI in it?
If you are a car buff, I am sure you heard of the popular engine of yesteryear that helped create the muscle car phenomenon. After its disappearance in the 1970s the Hemi engine became a legend in its own time, a synonym for a large powerful engine. But lately the word Hemi has been popping up frequently, in television ads and on billboards; you cannot help but wonder what is causing such a stir in the auto and truck world. The phrase, "Is that a Hemi," has become a popular saying among truck enthusiasts. So what makes this engine stand out from the others? What makes so powerful?
The Hemi engine for autos was first introduced in 1951. Chrysler stunned the automotive world with its 180 horsepower V8 Hemi, an unheard of amount of power in this era. Through out the years the hemi was known for setting speed records, it was used in drag and race cars by such popular names as Don Garlits and Richard Petty. In fact, Garlits was the first to break 200 mph in a quarter mile in a Hemi dragster. In 1966 Chrysler introduced the Street Hemi and the rest is history. The Hemi became a legend in its own time, when you see a Plymouth Roadrunner or Barracuda you cannot help but wonder if there is a massive 426 Hemi under the hood. After the muscle car phenom ended in the 1970s the production of the Hemi engine ceased, the end of an era. But the Hemi has returned, you can find one in Dodge trucks and SUVs, it is also due to appear in Dodge Magnum police cars.
The Hemi engine as its name implies is all related to the design of its combustion chamber and cylinder head, the area above the piston where the air and fuel mixture are ignited to push the piston down and develop power. In the Hemi engine, the top of the combustion chamber and the cylinder head form a hemispherical design, hence the word "Hemi". The spark plugs, which ignite the air and fuel mixture, are located on top of the chamber and the valves open on opposite sides of the combustion chamber, a unique design. How does this translate to power and efficiency? Since the valves are located on opposite sides of the cylinder head due to the hemispherical design, there is room for larger valves. Larger valves equal more air, fuel, and the quick release of unburned exhaust gases. This design also enables the air/fuel mixture to be superheated; the pressure increase due to the spherical chamber allows higher pressures, which burns the fuel more rapidly and quickly. This may sound a bit confusing but the bottom line is that the engine is made to bring in large amounts of air and fuel and then utilize the space and placement of the spark plug to ignite it efficiently.
The advantages of the Hemi engine are less unburned gases, which in turn lower emissions and increases fuel mileage, not to mention horsepower. The larger valves also allow the engine to breathe better; the engine does not have to work harder to produce power. Now if you're looking for a vehicle that will give you 40 miles to the gallon, this is not the engine for you. Although the Hemi in Dodge trucks are very fuel efficient when compared to trucks with similar size engines, it is still a large, powerful V8 engine. So the next time you come across a Dodge truck or SUV owner and he or she has a smile on their face, ask them, "Does that thing have a HEMI in it?
