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New 2005 Jeep Grand Cherokee to Offer Cylinder Deactivation with HEMI

High-Tech V6 and V8 Engines plus 5-Speed Automatic Transmission to Improve Fuel Economy

Chrysler Group has recharged the HEMI engine icon in recent years to be synonymous with class-dominant power in its Dodge Ram truck and Durango SUV models as well as the popular new Chrysler 300C.

But these arent the only vehicles to make use of the 5.7-liter engine. The new Dodge Magnum sport wagon, which shares general architecture with the 300 sedan, debuts this week in dealerships across America, also featuring the all-powerful HEMI in top-line R/T trim.

Next on the HEMI agenda will be the all-new Jeep Grand Cherokee.

From the Ram pickup truck to the Magnum sport wagon, Chrysler Group has put the HEMI V8 into wide use across its lineup. (Photo: Trevor Hofmann, American Auto Press)

But unlike its Dodge truck and SUV cousins, it gets a similar version of the engine as featured in the 300C and Magnum, albeit output is reduced to 325 horsepower and 370 lb-ft of torque. The difference between the car and truck engines comes down to Chryslers Multi-Displacement System (MDS), the first cylinder deactivation system sold in North America

The next vehicle in the Chrysler garage to get the HEMI treatment is the all-new Jeep Grand Cherokee. (Photo: Trevor Hofmann, American Auto Press)

on large-volume vehicles. MDS increases fuel economy by up to 20 percent while still delivering all the power and torque that the new HEMI V8 is becoming legendary for.

"The Chrysler Group MDS seamlessly alternates between smooth, high fuel economy four-cylinder mode when less power is needed, and V8 mode when more power from the 5.7L HEMI engine is in demand," commented Eric Ridenour, Executive Vice President Product Development, Chrysler Group. "This optimizes fuel economy

MDS increases fuel economy by up to 20 percent while still delivering all the power and torque that the new HEMI V8 is becoming legendary for. (Photo: DaimlerChrysler)

when V8 power is not needed, without sacrificing vehicle performance."

New developments such as high-speed electronic controls, sophisticated algorithms controlling the systems and the integration of electronic throttle control have made the technology possible. As a result Chrysler Group reports a seamless deactivation and activation process, needing only 40 milliseconds (0.040 seconds) to transition from eight-cylinders to four or vice versa.

So how does it work? Essentially MDS deactivates the valve lifters in four of the V8s cylinders (1, 7, 4 and 6), resulting

Chrysler Group conducted more than 6.5 million customer-equivalent miles of development and durability testing before the MDS-equipped HEMI became available. (Photo: Trevor Hofmann, American Auto Press)

in four closed valves and zero combustion in half the cylinders. Fortunately the "dead" cylinders dont drag energy from the working four, due to air being pumped through those cylinders temporarily out of action.

"The MDS was part of the engines original design," said Bob Lee, Vice President Powertrain Product Team, Chrysler Group. "This resulted in a cylinder-deactivation system that is elegantly simple and completely integrated into the engine design. The benefits are fewer parts, maximum reliability and lower cost."

In case the reliability of such new technologies concerns you, Chrysler Group conducted more than 6.5 million customer-equivalent miles of development and durability testing

It only makes sense that bigger vehicles like the Dodge Ram and Durango would greatly benefit from Chryslers MDS setup. (Photo: Trevor Hofmann, American Auto Press)

before the MDS-equipped HEMI became available. The automaker adds the additional comfort of a 7-Year/70,000 mile limited powertrain warranty as well.

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