New Hemi Engines 2003-Present. Larry Shepard

Чтение книги онлайн.

       This cutaway of the 392 Gen III Hemi shows the internals of the production engine, also called a 6.4L. Except for the intake system, it is similar to the 6.2L Hellcat/Demon supercharged engines. (Photo Courtesy FCA US LLC)

      Because of these changes, swapping parts from the new 5.7L Eagle to the original 5.7L does not work. Rebuilds must use basic service parts for the engine being rebuilt. There are some exceptions, which I’ll discuss in future chapters.

       The 6.1L Engine

      The 6.1L 372-ci Hemi engine was introduced in 2006 and was produced through 2011. It was a big-bore version of the 5.7L with a 4.055-inch bore that was sometimes rounded up to 4.06 inches. This bigger engine had a different block casting but shared the 3.58-inch stroke with the 5.7L. It was originally rated at 425 hp or 1.14 hp/ci.

      The 6.1L’s 2.075-inch valves were slightly larger than the 2.05-inch valves of the 5.7L Eagle, but they were much larger than the original 5.7L’s 2.00-inch valves. The valves are slightly longer and the installed spring height is slightly higher (1.87 inches versus 1.81 inches).

      The key to this engine’s performance package is the much bigger camshaft. The 6.1L’s valve lift increased almost 0.100 inch more than the 5.7L standard and Eagle cams, going from 0.472-inch to 0.571 inch lift and 0.460 inch versus 0.551 inch on the exhaust. The advertised duration picked up about 20 degrees, showing 260 versus 283. At 0.571-inch valve lift, this has to be one of the highest lift cams ever used in a production engine. The previous high-lift, high-performance production engine cams of the muscle era (426 Hemi, the 340, the 440-6, etc.) used cams with production lifts around 0.450 to 0.475 inch. High-performance aftermarket cams for these engines tended to peak at around 0.510 inch. The 0.571-inch lift was impressive for production, street, warranty, and emissions considerations! The 6.1L engine was the only V-8 engine in the SRT models in this era.

       The 6.4L 392 Engine

      The 6.4L 392-ci version of the Gen III Hemi engine had somewhat of an identity crisis. It was originally called the 392, then production called it the 6.4L, and then it was back to the 392. It is the same displacement either way. In the last couple of years, production seems to have settled on 392.

      This 392 engine package is also called the Apache. It is rated at 470 hp (2011) or 490 hp (2016–2017), which is 1.20 hp/ci. It has the largest valves to date from the production Gen III Hemi engines with 2.138-inch intakes and 1.654-inch exhausts. It also features the raised valvetrain with the tallest installed spring heights at 2.051-inch intake and 2.016-inch exhaust.

      The big port Apache head flows almost 340 cfm. The beer-barrel shaped intake manifold is lightweight plastic and features an angled, single-inlet throttle body mount. It also has variable valve timing (VVT). One interesting feature of the Gen III Hemi engines was that they all had windage trays that were designed as part of the oil pan gasket rather than as three pieces with a separate tray and an oil pan gasket on top and bottom.

       The 6.2 Supercharged Hellcat/Demon

      The Hellcat was introduced in 2014–2015 and became Chrysler’s first supercharged engine. The Hellcat engine was similar to the 6.1L and 6.4L Hemis. It used a cast-iron block with a 4.09-inch bore, which was the same as the 6.4L 392. It also used the 6.1L’s 3.58-inch stroke. This made the engine a 6.2L version at 378 ci. The engine was rated at 707 hp and 650 ft-lbs of torque, the highest horsepower rating for any production engine. The Hellcat blocks were painted orange.

      The Hellcat used a similar cam as the 392 with a 0.571-inch lift, but it had 8 degrees fewer intake duration and 16 degrees more exhaust duration. The twin-screw supercharger was built by IHI Turbo America and displaced 2,380 cc. The boost pressure was electronically regulated to 11.6 psi. The supercharger was driven by the serpentine drive belt and the aluminum heads used smaller valves than the 392 engine. It maintained the long valves and tall installed height.

      When the Hellcat was introduced, no one thought that this production output level could be matched because racing and custom builds have unique emissions and warranty situations that relate to production engines. Many felt that if it was going to be topped, it would only be by 10 or 20 hp. That held true for a couple years, and then the 2017 Demon burst on the scene with 840 hp! The Demon uses the same basic 6.2L engine as the Hellcat, but the supercharger is larger on the Demon at 2,900 cc and 14 psi boost pressure compared to the Hellcat’s 2,380 cc with 11.8 psi.