How Much HP Does A Gen 3 HEMI 6.1L Engine Have & Which Cars Originally Came With One?

When Chrysler introduced the Gen 3 HEMI in 2003 as a replacement for the Magnum engine, it was received with much fanfare, not only because of its iconic status and staggering power, but also because it had been 32 long years since the HEMI engine was last available. Chrysler previously ceased production of the legendary 425-hp, 426 street HEMI V8 engine back in 1971 due to tightening emissions standards, which forced consumers to turn their attention to more economical options. The 5.7-liter V8 was the first of the Gen 3 HEMI engines to launch, followed by the 6.1-liter HEMI V8, which debuted two years later in 2005 and remained in production until the 2010 model year.

The HEMI 6.1-liter engine is based on the 5.7-liter V8, but there are differences between the two engines. The 6.1-liter HEMI has a larger 370 cubic-inch displacement due to a wider cylinder bore and slightly longer stroke, measuring 103 millimeters (4.06 inches) × 90.9 millimeters (3.58 inches). For context, the 5.7-liter HEMI V8 engine's bore was 99.49 millimeters (3.92 inches), while the stroke measured 90.88 millimeters (3.58 inches). In addition to the enlarged displacement, the 6.1-liter HEMI V8 engine also received several other upgrades that enabled it to make more power than the 5.7-liter variant. 

These include high-flow cylinder heads, strengthened cylinder block, lighter pistons cooled by oil jets, reinforced connecting rods, a forged crankshaft, reworked coolant channels, a 2.75-inch exhaust system, unique camshaft profile, as well as a new intake manifold tuned to deliver high-speed performance. The compression ratio was also increased from 9.6:1 to 10.3:1, with all of these changes resulting in an engine robust enough to handle 425 horsepower and 420 pound-feet of torque.

The 2005 Chrysler 300C SRT-8 was the first car to feature the Gen 3 HEMI 6.1-liter V8 engine. And with 425 hp and 420 pound-feet of torque at the ready, the muscle sedan could sprint to 60 mph in about five seconds. If you're documenting the scores, that output means the 2005 Chrysler 300C SRT-8's 6.1-liter HEMI V8 has 85 extra ponies over the 5.7-liter engine version. Sadly, that immense power comes at the expense of fuel economy. The Gen 3 HEMI 6.1-liter engine doesn't have the Multiple Displacement System (MDS), a smart technology that shuts off some of the engine's cylinders to enhance efficiency in low-load driving situations.

The 2005 Chrysler 300C SRT-8 returns an EPA-estimated 13 mpg city, 18 mpg highway, and 15 mpg combined. By comparison, a 2006 Chrysler 300 with an MDS-equipped 5.7-liter HEMI V8 gains 15 mpg city, 23 mpg highway, and 18 mpg combined, making it marginally more efficient than its more powerful sibling. Asides from the Chrysler 300C SRT-8, the Gen 3 HEMI 6.1-liter also found application in the Dodge Magnum SRT-8 (2006-2008), Jeep Grand Cherokee SRT-8 (2006-2010), Dodge Charger SRT-8 (2006-2010), and Dodge Challenger SRT-8 (2008-2010).