Once a legendary muscle-car motor, the new Hemi V8 is a high-profile driver in the Chrysler Group’s resurgence, powering everything from pickups to sedans.
“It will be our icon engine,” says Wolfgang Bernhard, chief operating officer of the Chrysler Group, a division of DaimlerChrysler AG that includes Dodge, Chrysler and Jeep.
“Hemi” refers to hemispherical combustion chambers. The combustion chamber is where gas and air are squeezed into an explosive charge by the piston. Many are triangular in shape. A true hemispherical combustion chamber looks like half of a ball and allows the engine to inhale more air and gas.
The former Chrysler Corp.’s first Hemis appeared in the ’50s, evolving into the mighty 426-cubic-inch Hemi of the ’60s that was rated conservatively at 425 horsepower.
The engine disappeared from Chrysler’s lineup more than 30 years ago, mostly because it was big, costly, devoured gas and had high emissions at low speeds.
Bob Lee, director of powertrain systems at the Chrysler Group, said his engineers were not trying to re-create the old Hemi when they came up with the current modern version of the motor. They were mostly looking for a replacement for the group’s old 5.9-liter engine and considered several options.
“When we got done, we realized that the best trade-off was the Hemi — it has the best combustion, superior breathing and best cost,” he said. Work began on the new engine in 1999.
The engineers solved the old engine’s low-speed emissions problem by fitting each cylinder with two spark plugs, Lee said. Most engines have one spark plug per cylinder.
The current Hemi is smaller than the last one — at 5.7 liters, it is about 348 cubic inches. But the engine is rated at 345 horsepower in the Dodge Ram pickup, which almost meets the one-horsepower-per-cubic-inch goal that the Hemi engineers in the ’60s strived to attain.
