Performance gains through a hemispherical combustion chamber were proven on a racetrack decades ago. The world of NASCAR racing was put on its ear when a Hemi-powered car blistered Daytona in 1964, only to see the engine outlawed later. The reason for its banishment was the fact that it was a purpose-built race engine and not available in street machines. After a year out, Chrysler bit the bullet, produced a street version, and the racing efforts picked up right where they left off.

Fast-forward several decades. The street Hemi fell victim to environment concerns and rising gasoline prices. It became a museum piece with a sort of reverence that is held only for the elite. If you saw it on the street, it was beneath the hood of a vintage muscle car, proudly restored by a dedicated owner.

As the automotive scene evolved, the power and performance aspects for light-duty and heavy-duty truck lines began to get more attention. With the knowledge acquired from the first two generations of the Hemi, Chrysler set about for a resurgence of a proven winner.

The dawn of the 21st century brought about the 50th anniversary of the legendary Hemi. Soon, Chrysler put the Hemi back on the street, this time encapsulated in Dodge trucks.

Truck buyers can now have the power and performance of the Hemi engine, completely legal within the boundary of modern restrictions. The engine is standard on the 2500 (31/44-ton) and 3500 (one-ton) series. Recently, Dodge put the engine into the option group for the 1500 Ram with the option running about $800.

The new Hemi is officially called the 5.7-liter Hemi Magnum V-8. It replaced the 5.9-liter engine previously found in the trucks. The 5.7-liter Hemi is capable of producing 100 more horsepower and 40 more ft./lbs. of torque than the 5.9-liter model. In addition, the hemi engine is about 60 pounds lighter, and fuel efficiency is about 10 percent better. There is also an improvement in the emissions range for the 5.7-liter Hemi as compared to the 5.9-liter equipped trucks.

The Hemi engine borrows heavily from the theory of its predecessor, but the modern technology replaces plenty of the original workings of the 426 model. Two features that carried over are critical to the engine's workings. The hemispherical combustion chambers that gave the hemi its moniker are an integral element. These chambers feature the large valves that put the spark plugs close to the center of the combustion chamber. Another original idea in the new model is the cross-flow valve arrangement that puts the valves perpendicular to the crankshaft centerline.

The Hemi is an internally balanced pushrod 90-degree V-8 engine (OHV) with a cast-iron block. The cast-iron block is a deep skirt model with cross-bolted main caps. Cylinder bore spacing is the same as the 5.9-liter model. The engine has two valves per cylinder (aluminum alloy heads) and also features dual spark plugs and a coil-over-plug ignition. There is an integrated air fuel module (IAFM) that utilizes the function of 26 components in induction and fuel system. The designers focused on engine sealing, using a combination of premium elastomeric materials and state-of-the-art application practices. The simple and efficient design of the engine was directed at easing servicing and repair.