Got a Hemi? Your 2005 Grand Cherokee Does!

Date 2004/4/10 0:00:00 | Topic: Grand Cherokee

An optional Hemi V-8 is not available on the Grand Cherokee
(from a DaimlerChrysler press release)

This is the year for Jeep® Grand Cherokee firsts, including two engines never before offered in the vehicle and two five-speed automatic transmissions. The 3.7-liter SOHC V-6 and 5.7-liter HEMI® V-8 offer more power and improved refinement as the base and top engines available in Grand Cherokee. Not to be outdone, the 4.7-liter SOHC V-8 has also received refinements which result in quieter and smoother operation.

“Two legends combine with the introduction of the modern HEMI V-8 in the 2005 Jeep Grand Cherokee,” said Eric Ridenour, Chrysler Group Executive Vice President – Product Development. “The HEMI is the most powerful engine ever offered in a Grand Cherokee and easily gives the vehicle best-in-class power.” 

5.7-Liter HEMI V-8
The modern HEMI has been engineered to deliver outstanding performance and reduced noise, vibration and harshness (NVH), resulting in a highly refined powerplant. The engine gives the Grand Cherokee best-in-class power and 90 percent of the engine’s peak torque is available from 2400 through 5100 rpm for excellent performance. The engine produces 325 hp (242 kW) @ 5100 rpm and 370 lb-ft (502 N•m) @ 3600 rpm.

Fuel economy has also been improved, but not at the expense of HEMI performance. Chrysler Group has developed the Multi-Displacement System (MDS) that deactivates four cylinders when the V-8 is not needed. No other manufacturer offers fuel-conserving MDS in an SUV.

The Chrysler Group MDS seamlessly alternates between smooth, high fuel-economy four-cylinder mode when less power is needed and V-8 mode when more power from the 5.7-liter HEMI engine is in demand. This optimizes fuel economy when V-8 power is not needed, without sacrificing vehicle performance or towing capability. 

"The MDS was part of the engine’s original design,” said Bob Lee, Chrysler Group Vice President – Powertrain Product Team.  “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."

Some of the significant technologies enabling the MDS include the speed of electronic controls, the sophistication of the algorithms controlling the systems and the use of Electronic Throttle Control (ETC). The HEMI will be able to transition from eight cylinders to four in 40 milliseconds (0.04 seconds).

"We challenge any driver to discern when the engine switches from either eight-to-four, or four-to-eight cylinder operation," said Lee.

This engine with MDS has completed over 6.5 million customer-equivalent miles through Chrysler Group’s development and durability testing.  It is covered by the 7-Year/70,000-mile Limited Powertrain warranty.

The HEMI engine that powers the 2005 Jeep Grand Cherokee uses aluminum cylinder heads with hemispherical combustion chambers, creating outstanding airflow leading to high power and torque. Dual ignition (two spark plugs per cylinder) increases peak power and torque, reduces exhaust emissions, increases fuel economy and provides a smooth idle. The combustion system has been refined and the engine uses direct-mount accessories for quieter operation. 

4.7-Liter SOHC V-8 Engine
The 4.7-liter V-8 has been updated and is now the mid-range engine in Grand Cherokee.  The engine produces 230 hp (172 kW) @ 4700 rpm and 290 lb-ft (393 N•m) of torque @ 3700. Dual knock sensors have been added for 2005 and enable improved engine calibration for both fuel economy and power output.

The engine has improved NVH characteristics, realized through the use of composite valve covers, structural improvements to the air box and resonator and improved dampening of the heat shields. 

3.7-Liter SOHC V-6 Engine
The 3.7-liter V-6 engine provides the 2005 Jeep Grand Cherokee with an efficient, durable and smooth base engine. It produces 210 hp (157 kW) @5200 rpm and 235 lb-ft (319 N•m) @4000 rpm.  The 3.7-liter SOHC V-6 will replace and deliver even more peak power than the previous 4.0-liter I-6 in the Jeep Grand Cherokee lineup.  The engine was first introduced in the Jeep Liberty and has been continuously refined to provide smooth V-6 power with optimal economy.

Significant changes in the 3.7-liter include a revised cam profile and new valve lash adjusters.  These changes improve the engine smoothness at idle. To ensure quiet operation, a new thick-wall composite manifold is new for 2005, as are structural improvements to the air box and resonator.

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