Third-Generation Hemi
Development of the engine that would become the new Hemi began in the latter half of the 1990s. Chrysler engineers faced the realization that the stalwart 5.9L Magnum V-8 truck engine-an engine known more commonly by its 360ci displacement and whose basic architecture originated in the '50s-wouldn't meet the performance requirements of the coming decade. This included not only the horsepower and torque figures Chrysler needed to remain competitive with new products from General Motors and Ford, but also the federal mandates for emissions and fuel economy.
Retired Chrysler engineer Rich Schaum initially proposed the new V-8 to Robert Lee, Chrysler's vice president of powertrain engineering, in 1996, but the word "hemi" was never mentioned. As the engine would be an all-new "clean sheet" design rather than an update of existing engines, the engineering staff evaluated a variety of engine configurations. One of the favorite designs was the water-cooled flat-six engine of the Porsche Boxster that happened to have hemispherical combustion chambers.
The first new Hemi engine prototype was started ceremoniously and without a hitch, but the engine had not been officially named a "Hemi"-although its design left little doubt. The original name, given even before the decision to go with a Hemi design, was "Ram." The marketing types at the company knew better and the third-generation Hemi, like its predecessors, became an instant success when it was introduced on the '03 Ram pickup.
The Alloy Options
While the iron Hemi block is marketed by Mopar Performance, World Products offers exclusive versions in lightweight aluminum or exotic graphite. The aluminum block is virtually identical to the cast-iron version, but it features screw-in galley plugs and cast-iron cylinder liners. It is also 166 pounds lighter, weighing in at about 142 pounds-that's a huge reduction over the iron block and a better-balanced proposition for street rods.
The aluminum case is a premium piece, cast at a foundry that is renowned for its work with Formula 1 racing teams, with the cylinder liners seated with O-rings to prevent oil from squeezing up between the block and liners. It also features larger cross-valley ribs that enhance rigidity. Because the aluminum block uses iron cylinder liners, its maximum bore doesn't match the iron block's 4.600-inch maximum, but it is available with 4.500-inch bores, which still permits the creation of a 600-inch Hemi.
The admittedly expensive compacted graphite Hemi block, which is designed for the rigors of racing, offers the ultimate in strength; it's about 75 percent stronger than conventional gray iron. If you're not familiar with compacted graphite, it is an extremely dense material-with minute parts of magnesium and titanium-that offers excellent thermal properties and supreme durability. It is neither inexpensive nor lightweight, but it's just about impossible to break.
Graphite Hemi blocks come with rough 4.240-inch bores that are finished to 4.250 inches. In addition to the standard Hemi specs, we understand the graphite version will be available with a raised camshaft position, as well as a shorter 10.200-inch deck and cut-down water jackets.
While the graphite block is at home at the dragstrip, we suspect more than a few enthusiasts will be tempted to build a street-based Hemi with the admittedly exotic aluminum block. Besides a significant weight savings over the front wheels, there's an undeniable wow factor.