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. 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 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 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 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 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.

With the new Grand Cherokee bringing cylinder deactivation into Chrysler Groups SUV family, and higher fuel efficiency requirements in the light truck and SUV segment being mandated by Washington over the next few years, it only makes sense for the Dodge Ram and Durango to incorporate the fuel saving technology. Chrysler Group insiders have smiled, winked and therefore hinted that such would be the case in the not too distant future.

For the time being, the Jeep Grand Cherokee will be the only SUV to offer MDS, combining the best in power and fuel efficiency into one package. Those not wanting as much output can opt for an all-new base engine, the same 210 horsepower 3.7-liter SOHC V6 with 235 lb-ft of torque that is currently featured in the top-line Liberty. While the new engine provides smoother, quieter operation, greater power, better space optimization plus improved fuel economy, it will be hard to say goodbye to the venerable 4.0-liter I-6, an engine thats been in the Jeep Grand Cherokee lineup for decades. Bridging the gap, the efficient 4.7-liter SOHC V8 will soldier on with 230 horsepower and 290 lb-ft of torque.

No matter the engine chosen, all Grand Cherokees will feature a 5-speed automatic transmission, reportedly delivering smoother shifts and improved fuel economy in V6 and V8 applications. The unit mated to the 3.7-liter V6 will be all-new, while the current 545RFE 5-speed automatic will be joined up with the 4.7-liter V8 once again, and become the standard gearbox for the top-line 5.7-liter V8 as well. While it increases the SUVs maximum towing capacity Jeep also says its been "refined for higher-quality shifts."

The new 2005 Jeep Grand Cherokee will be available this fall.