Author: Zahari Mladenov

Now in its second generation, the legendary 5.7-liter HEMI® V-8 engine has once again earned a place on Ward’s distinguished “2009 10 Best Engines” list. Relentlessly delivering powertrain excellence, Chrysler LLC has earned Ward’s “10 Best” award six times in the last seven years with the iconic 5.7-liter HEMI engine.

“The HEMI earns the honor not on pure emotion or brute force but with advanced new technology such as variable valve timing, which allows cruising in four-cylinder mode about 40 percent of the time, which is twice as much as the previous-generation Multi-Displacement System cylinder-deactivation system,” said Tom Murphy – Executive Director of Ward’s AutoWorld magazine. “A number of Ward’s testers managed to top 19 mpg (12.3 L/100 km) with the HEMI, putting it in line with certain premium V-6s tested.”

With improved Multi-Displacement System (MDS) technology for increased fuel efficiency, added refinement and more power, the all-new 2009 5.7-liter HEMI V-8 engine delivers world-class performance and technology in nine Chrysler, Jeep and Dodge vehicles. The 5.7-liter HEMI V-8 engine with MDS technology is available on 2009 Chrysler 300C, Chrysler Aspen, Jeep® Grand Cherokee, Jeep Commander, Dodge Charger, Dodge Durango, Dodge Ram Heavy Duty series and the all-new 2009 Dodge Ram 1500 and Dodge Challenger.

“We are honored to have our iconic HEMI engine recognized by Ward’s for a sixth time,” said Bob Lee, Vice President – Powertrain Product Engineering Team, Chrysler LLC. “HEMI is synonymous with performance, and now — thanks to VVT, expanded four-cylinder mode in our MDS system, and a host of other technologies — Chrysler’s new 5.7-liter HEMI V-8 engine delivers more fuel efficiency and refinement, along with even more power.”

While the new 5.7-liter HEMI V-8 engine maintains the key architecture that makes “HEMI” synonymous with “performance,” Chrysler powertrain engineers improved engine breathing and added new technologies, including Variable Valve Timing (VVT), that substantially improve fuel economy and refinement.

The HEMI’s new VVT improves fuel economy in two ways. First, it reduces the engine’s pumping work by closing the intake valve later. Second, it increases the expansion process of the combustion event. This allows more work to be transferred to the crankshaft instead of being rejected out of the exhaust port as heat. Essentially, VVT improves engine breathing, which improves engine efficiency and power.

Dodge’s fuel-saving MDS system seamlessly alternates between smooth, high-fuel-economy four-cylinder mode when less power is needed, and V-8 mode when more power from the new 5.7-liter HEMI engine is in demand. This optimizes fuel economy when V-8 power is not required, without sacrificing vehicle performance or capability.

An expanded MDS operating range in the new-for-2009 HEMI will allow customers to realize an even-greater fuel economy benefit. Chrysler estimates that since its inception of MDS in 2005, more than 100 million gallons of gasoline have been saved, along with reduced carbon dioxide (CO2) emissions of close to one million

When MDS is operating, it is indicated by a “Fuel Saver” readout in the vehicles Electronic Vehicle Information Center.

In addition to VVT and expanded MDS operating range, the HEMI’s fuel economy and performance improvements result from an increased compression ratio, an active intake manifold with long runners for low-end torque and short runners for high-rpm power, improved cylinder head port flow efficiency, and reduced restriction exhaust and induction systems.

Numerous other hardware upgrades were implemented to build on the quality, reliability and durability reputation of the HEMI engine. These include crankshaft structural upgrades, a dual-mass crankshaft damper, new piston design, improved valve-spring design and oil pump capacity increase for VVT.

The new 5.7-liter HEMI V-8 engine is manufactured at the Saltillo Engine Plant in Saltillo, Mexico.