Everything to know about the 2003 to 2023 HEMI

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scottm
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Everything to know about the 2003 to 2023 HEMI

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From SRT to Demon, here's everything there is to know about the 2003 to 2023 Gen III HEMI V8
https://insights.globalspec.com/article ... i-hemi-v-8
While many cars and trucks of the Eighties and Nineties dispelled the notion that American performance died off with the original muscle cars, it took an entirely new engine — one more powerful and less expensive to produce than its predecessor — to reignite the horsepower wars and usher in a new golden age. The HEMI V-8 has since become a standard-bearer for Chrysler, Dodge, Ram and Jeep vehicles, and its basic engine architecture has spawned more than a dozen configurations, some of them difficult to discern from others. For that reason, we've put together this spotters guide to the third generation (or gen 3) HEMI family of engines.

What sets the HEMI apart

Teased in the 2000 Chrysler 300 HEMI C and the 2001 Dodge Super8 Hemi, the new 5.7-liter HEMI (Chrysler stylizes it as HEMI, but for expediency's sake, we will not) debuted in the 2003 Dodge Ram pickups, featuring a deep-skirt cross-bolted iron block, aluminum heads, overhead valves, 4.46-inch bore spacing, the same bellhousing bolt pattern as the Chrysler LA-series V-8s, coil-on-plug ignition, composite intake manifolds, multipoint fuel injection and that controversial head design.

Like the second-generation 426 HEMI, the 5.7L HEMI heads featured a camshaft in the block, opposed valves for a true crossflow design, twin spark plugs and rocker shafts. The third-generation Hemi did not, however, feature a full hemispherical combustion chamber. Instead, Chrysler's engineers decided to flatten either side of the combustion chamber to improve combustion efficiency and emissions. Some might argue that doesn't make the engines true HEMIs, but then again, the HEMI V-8s of yore were massive, heavy engines that cost a lot to machine and that wouldn't meet modern-day fuel-efficiency or emissions requirements.

Even though prevailing internal combustion engine design called for multiple valves operated by overhead camshafts (indeed, one of the engines the HEMI replaced, the 4.7L PowerTech V-8, used single overhead camshafts), the HEMI stuck with a two-valve, pushrod design. As they did with GM's LS-series V-8s, critics scorned that layout as antiquated and unable to meet power, mileage and emissions demands. However, Chrysler's engineers made the most of it by taking Tom Hoover's advice to relocate the camshaft upward in the block, thus shortening the pushrod length and improving valve train geometry.

What's more, as Allpar reported, the Hemi proved less expensive to manufacture than previous hemispherical-head designs, which meant the engines could turn a profit just as easily as they could turn into ad copy gold.

5.7-liter HEMIs

After debuting in the Ram truck line, by 2005 the HEMI migrated to the LX-chassis cars (Dodge Charger R/T, Dodge Magnum R/T, Chrysler 300C) with the same 5.7-liter (345-cu.in.) displacement but a few changes. Truck engines — rated at 345 hpr in the Ram, 335 hp in the Grand Cherokee, Durango and Aspen — continued to use their own intake manifolds that mounted the throttle body atop the manifold. Meanwhile, car engines — rated at 350 hp in the Charger Daytona R/T and 340 hp in the other cars — moved the throttle body to the front of the intake. The 2005 car engine revisions also saw the introduction of the Multi-Displacement System, which deactivates four of the eight cylinders at cruising speed to improve mileage.

The most significant revisions to the entry-level HEMI came in 2009, with the so-called Eagle 5.7L Hemi. The 3.917-inch bore and 3.58-inch stroke remained the same, but Chrysler engineers added new heads, which reduced the combustion chamber volume from 85-cc to 65-cc and which flowed better with square intake ports and D-shape exhaust ports; Variable Camshaft Timing, which advances or retards timing by up to 37 degrees; larger intake valves; beefier connecting rods; a 58-tooth crankshaft sensor wheel; and a 10.5:1 compression ratio. The Eagle HEMI also features an active intake manifold with a flapper door that switches from long intake runners to short runners at higher rpms. The end result: anywhere from 360 to 375 hp in cars and SUVs and anywhere from 383 to 395 hp in Ram trucks.

Note that Chrysler engineers also built a version of the Eagle 5.7L specifically for the 2009 Durango and Aspen hybrids. These used a special camshaft and still used exhaust gas recirculation (EGR) valves after Chrysler had eliminated EGR from all other HEMIs. Poorly received when new, the likelihood of coming across one of these in the wild nowadays is slim.

To identify one, look for a "5.7L" cast into the side of the block just above the oil pan mounting surface.

SRT HEMIs

Along with the 2005 changes to the 5.7L, DaimlerChrysler also introduced the first SRT-8 engine that year, the 6.1-liter (370-cu.in.) HEMI. More than just a bump in displacement thanks to a larger 4.055-inch bore, the 6.1L featured an aluminum intake manifold (the only third-gen HEMI that didn't have a composite intake manifold), forged crankshaft, D-port cylinder heads with 74-cc combustion chambers and 2.08-inch intake valves and 1.60-inch sodium-filled exhaust valves, aluminum exhaust manifolds, bigger fuel injectors, oil squirters aimed at the underside of the pistons, and a more aggressive camshaft. Combined, these modifications make for a nice heritage-inspired horsepower figure of 425 (in the SRT-8 versions of the 300C, Magnum, Charger, and Challenger; 420 in the Grand Cherokee SRT-8). Look for a "6.1L" cast into the side of the block just above the oil pan mounting surface.

Rather than upgrade the 6.1L as with the Eagle 5.7L, in 2011 Chrysler engineers replaced the 6.1L altogether with the 6.4-liter HEMI, also sometimes referred to as the 392 or the Apache, an engine that technically debuted in 2010 on the Challenger Drag Pack cars. Along with the displacement increase (the result of a larger 4.090-inch bore and a longer 3.72-inch stroke), the 6.4L benefited from a 10.9:1 compression ratio, 2.14-inch intake and 1.65-inch exhaust valves, the 6.1L's oil squirters, an even more aggressive camshaft, and an active intake manifold like that found in the Eagle 5.7L. Initially rated at 470 hp, the 6.4L bumped to 485 hp in 2015 with the introduction of the Scat Pack cars (Grand Cherokee and Durango SRT versions of the 6.4L bumped too, but just to 475 hp; the 6.4L in the Wrangler Rubicon 392 produces 470 hp). All 6.4L car and SUV engine intake manifolds have a front-mounted throttle body angled toward the driver's side of the vehicle. Look for a "6.4L" cast in the side of the block.

At roughly the same time that FCA bumped the output of the 6.4L, it also made the larger HEMI available in the Ram 2500 and heavier trucks. Essentially similar to the 6.4L used in the cars and SUVs, the truck version used a BGE (Big Gas Engine) block with improved casting processes, higher nickel content and a slightly more rigid design. Horsepower figures varied from 366 to 410, depending on the application. Look for a "BGE" cast into the side or back of the block and an intake manifold that angles the throttle body toward the passenger's side of the vehicle.

Supercharged HEMIs

Here's the meat of the matter. With the relentless horsepower wars and GM's use of superchargers in the top-of-the-line LS V-8s, it was only a matter of time before FCA responded with a supercharged top-of-the-line HEMI of its own. While the Dodge Magnum SRT-8 concept car showed that Chrysler engineers were already thinking of a supercharged version of the HEMI as early as 2003, the production version — the Hellcat — came along in 2015, using a BGE block, a displacement of 6.2 liters (376 cubic inches), a 9.5:1 compression ratio, essentially the same heads as the 392, a larger 92-mm throttle body, and an IHI-built 2.4-liter twin-screw supercharger with integrated charge coolers good for 11.6 pounds of boost. Variable Cam Timing remained, but the Multi-Displacement System was deleted for all supercharged engines. Total output: 707 hp, enough to propel the Challenger and Charger SRT Hellcat editions to 199 MPH. Later model years bumped that up to 717 hp. Hellcats later make their way into the Grand Cherokee Trackhawk and the 2021 Durango SRT Hellcat and Ram TRX.

Done? Hardly. In 2018, Chrysler engineers replaced the Hellcat's 2.4-liter supercharger with a 2.7-liter IHI supercharger good for 14.5 pounds of boost, ran the air-conditioner system's lines through the intake charge cooling system, added bigger injectors, and stunned the world with the 808 hp Challenger Demon. With a Direct Connection tune and 100-octane gas, the Demon then put out 840 hp, enough for a 9.65-second quarter-mile time.

The Demon lasted just one year, but the basic Demon engine remained from 2019-on as the Hellcat Redeye, a 797 hp alternative to the regular Hellcat available initially in the Challenger and this year in the Charger.

Then, as a send-off to the third-generation HEMI, Dodge's engineers developed the Demon 170, a 6.2L engine capable of 1025 hp and 945 pound-feet of torque thanks to the 3.0L supercharger from the Hellephant crate engine (see below) and the ability to run on E85 fuel. When running on regular 91 octane pump gas, it throttles those numbers back to a. still-blistering 900 hp and 810 pound-feet.

On all of the supercharged engines, look for a "6.2L" cast into the side of the block.

Racing HEMIs

As if that weren't enough for third-gen Hemi variants, in 2015 Mopar released two Challenger Drag Pack engines just for drag racing. The first, an all-aluminum design with a 2.9-liter Whipple supercharger atop, uses a 4.070-inch bore and 3.400-inch stroke to achieve yet another heritage-inspired number of 354 cubic inches. The second version used a naturally-aspirated all-aluminum 426-cu.in. version of the Hemi, achieved with a 4.125-inch bore and 4.000-inch stroke.

One more variant came along last year: the Super Stock version of the Hellcat Redeye, tuned to add 10 more horsepower over the Redeye.

Crate HEMIs

Given that the bellhousing pattern carried over from the LA-series small-block V-8s to the third-gen HEMI series of engines, it didn't take long before owners of older Dodge and Plymouth muscle cars started to restomod their vehicles with newer HEMIs, so Mopar stepped in with crate versions of the engines early on and has rapidly expanded the options since.

Nowadays, the crate engine lineup includes a complete Eagle 5.7L; a complete 485-hp 6.4L; the 707-hp Hellcrate supercharged 6.2L; and — building on the Drag Pack program's success — the Hellephant, a 426 fitted with a 3.0-liter supercharger good for 15 pounds of boost and a total of 1,000 hp.

Exactly how much longer Stellantis will continue to produce the third-generation HEMI is anybody's guess at this point. Dodge and Chrysler have already announced the end of the Charger, Challenger and 300C platform mates after the end of the 2023 model year, which leaves just the Ram pickups, Durango, Jeep Grand Cherokee, Jeep Wagoneer and the Jeep Wrangler Rubicon 392 as vessels for the engine. Meanwhile, Chrysler's new Hurricane twin-turbocharged straight-six appears poised to replace the HEMI in truck platforms, so outside of the odd crate engine, we've likely seen the last major development of the third-generation HEMI.
Some good info on the various editions of the Gen III HEMI from the last 20 years.

#HEMI #57HEMI #354HEMI #61HEMI #370HEMI #64HEMI #392HEMI #62HEMI #376HEMI
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