6.1 Vs. 6.4 HEMI Engines: What's The Difference?

Comparing the 6.1-liter HEMI engine with its 6.4-liter HEMI successor reveals more similarities than differences. Chrysler's Street and Racing Technology (SRT) team released both HEMI engines with only six years between them. The 6.1 HEMI's 2005 debut followed shortly after Chrysler revived the HEMI badge with the 2003 release of the 5.7-liter HEMI. While the 6.1 HEMI was phased out of the SRT lineup following the 2010 model year in favor of the 6.4 HEMI, Dodge is retiring the third-generation HEMI engine entirely after the 2024 model year.

On the surface, other than the minor 0.3-liter (22-cubic-inch) difference in displacement between the 6.1-liter (370-cubic-inch) and 6.4-liter (392-cubic-inch) HEMI engines, the most notable difference is the power they produce. Other subtle differences include the 6.4-liter HEMI's use of variable valve timing and MDS, Chrysler's multiple displacement system designed to conserve fuel.

Upon opening the hood, it's easy to spot the 6.1 HEMI's metallic aluminum intake manifold. For comparison, the 6.4 HEMI uses a black composite intake with active dual-length runners. The active runner system is yet another way engineers attempted to save the HEMI by merging efficiency with performance.

Finally, the 6.1 HEMI was only available as an SRT power plant available in cars and SUVs spanning a total of six model years. On the other hand, the 6.4 HEMI enjoyed more variation and longer service with its additional heavy-duty Ram truck version and a 14-model-year lifespan.

The 6.1 HEMI first hit the streets under the hood of the 2005 Chrysler 300C SRT-8 with 425 hp and 420 lb-ft of torque. The following year it appeared in cars such as the Magnum and Charger. It was also used in the Jeep Grand Cherokee and in 2008 in the Dodge Challenger. The 6.1 HEMI power ratings remained consistent through its years of service except for a slight reduction to 420 hp in Jeep Grand Cherokees as its AWD components required a less efficient exhaust system.

The first 6.4 HEMI appeared as an option in the 2011 Dodge Challenger and expanded into the Dodge Charger, Chrysler 300, and Jeep Grand Cherokee in 2012. While not an SRT, Ram introduced a 6.4 HEMI for use in its heavy-duty models in 2014. The most recent inductees into the SRT 6.4 HEMI club are the Dodge Durango SRT in 2018, the Wrangler Unlimited Rubicon 392 in 2021, and the Jeep Grand Wagoneer lineup in 2022.

Specific tuning and equipment requirements would produce various power ratings over the years with the 6.4 HEMI making up to 485 hp and 475 lb-ft of torque depending on the vehicle. The heavy-duty Ram truck 6.4 HEMI produced 410 hp and 429 lb-ft of torque in its final iteration.