INHERIT THE WIND: THE SUPERCHARGED 6.2L HEMI® ENGINE
The GEN III HEMI® engine has seen numerous improvements and enhancements since its debut in the 2003 Ram 1500 pickup truck. Since its debut, the displacement has grown, and power levels have gone off the dyno chart. The modern HEMI engine has been installed in numerous cars and SUVs. In 2015, SRT® engineers dropped an A-bomb on their cross-town rivals with the introduction of the 707-horsepower, supercharged 6.2L HEMI engine. The competition was totally in shock when Dodge Challenger and Charger SRT Hellcats began to prowl the streets and drag strips. The distinct howl coming from the supercharger as the engine’s RPMs climbed sent chills along the spines of the opposition and had them running for cover. The supercharged 6.2L HEMI engine has also been installed in the Jeep® Grand Cherokee SRT Trackhawk, and soon it will find another home in the 2021 Durango SRT and Ram TRX.
Just when we thought the SRT Hellcat represented the pinnacle of HEMI engine performance, the second shockwave hit, shaking the ground within the automotive industry, as SRT engineers unleashed the 808-horsepower Challenger SRT Demon. With an available 100-octane tune, the horsepower levels went through the stratosphere with an 840 rating and it raised the bar even higher, leaving the supercar community numb. The Challenger SRT Demon set records while scorching the drag strips from coast to coast with nine-second time slips. The engine package was too good to be a one-year wonder, so in 2019, the Challenger SRT Hellcat Redeye was born with a slightly “detuned” Demon-inspired 6.2L HEMI engine pushing “just” 797 horsepower. In 2021, the Redeye engine option will be available on the Charger SRT Hellcat Widebody. There’s also a drag-specific yet street-legal Challenger SRT Super Stock package with a standard 807-horsepower supercharged 6.2L HEMI engine. Regardless of the power output, there are commonalities and differences between the SRT Demon, SRT Hellcat and SRT Hellcat Redeye supercharged 6.2L HEMI engines, so let’s take a closer look.
6.2L HEMI ENGINE BLOCK & ROTATING ASSEMBLY
The 6.2L HEMI blocks can be identified with casting number 5037473BE or 5037473BG and have “BGE” cast above the oil pan rail. The 6.2L HEMI blocks come painted orange (SRT Hellcat) or red (SRT Demon/SRT Hellcat Redeye/Super Stock) and are machined and assembled at FCA’s Saltillo Engine Plant. The 6.2L HEMI blocks are the “Big Gas Engine” (BGE) castings and have far thicker walls, higher nickel content and slightly shorter water jackets, providing increased cylinder wall rigidity/strength. The bore and stroke of the 6.2L HEMI engine measures 4.09 inches and 3.58 inches. For comparison, the bore and stroke on a 6.4L/392 HEMI engine comes in at 4.09 inches and 3.72 inches. Like the 6.4L/392 HEMI engine, the 6.2L version comes stock with a forged-steel crankshaft that can take a lot of punishment, but the pistons on the 6.2L HEMI engine are forged (versus cast hypereutectic on the 6.4L/392 HEMI engine) and come with oil squirters (to reduce heat). The 6.2L HEMI pistons are also a floating pin design and use a powdered metal I-beam design connecting rods but with additional material on the beam and using stronger rod bolts. These are also the same length (6.20 inches) as the 6.4L/392 HEMI engine. The factory compression ratio on the 6.2L HEMI engine is a healthy 9.5:1 and the horsepower ratings are 707-717 @ 6,000 RPM (SRT Hellcat); 797 @ 6,300 RPM (SRT Hellcat Redeye); 807 @ 6,400 RPM (Super Stock); and 808-840 @ 6,300 RPM (SRT Demon).
6.2L HEMI CYLINDER HEADS/CAMSHAFT
As with all GEN III HEMI V8 engines, the 6.2L SRT Hellcat supercharged HEMI engine uses an aluminum twin-plug cylinder head with an improved port and chamber design and larger valve sizes. It carries a casting number of 5037369BD, 68166435AA or 68166435AA-A02 depending on the year. The intake valve diameter measures 2.14 inches and the exhaust comes in at 1.65 inches. The valve lengths and valve spring heights are increased just like on the 6.4L/392 HEMI engines. Operating the valvetrain is a hydraulic camshaft with a duration of 278 degrees of intake and 304 degrees of exhaust with an overlap of 51 degrees. The intake lift is .571 inches and .536 inches on the exhaust with a centerline of 109 degrees. None of the supercharged 6.2L HEMI engines use the Multi-Displacement System (MDS), but do use variable cam timing (VCT). Depending on your performance needs, the factory camshaft makes plenty of power even with additional mods to the engine.
6.2L HEMI SUPERCHARGERS
The biggest difference between the SRT Demon/SRT Hellcat Redeye/Super Stock engines versus the SRT Hellcat 6.2L HEMI engine is the supercharger displacement. While all 6.2L HEMI engines use an IHI built twin-screw supercharger, the displacement will vary among the engines. The SRT Hellcat gets a 2.4L supercharger making 11.6 pounds of boost while the SRT Demon, SRT Hellcat Redeye and Super Stock have a 2.7L supercharger that produces 14.5 pounds of boost. Both superchargers have a side-mounted throttle body with an opening diameter of 92 MM. Regardless of the engine, the boost is electronically regulated, and the supercharger is driven off a dedicated 10-rib serpentine belt from the crankshaft. Many folks like to change the upper pulley on the supercharger, but it’s important to remember that a custom tune is required to handle the fuel needed for the additional boost. The 6.2L HEMI SRT Hellcat engine 2.4L supercharger is part number 53010863AA and the SRT Demon/SRT Hellcat Redeye/Super Stock supercharger carries part number 53010974AF. The part number can be found on the gear cover of the supercharger’s housing.
6.2L HEMI EXHAUST MANIFOLDS
When it comes to getting rid of the spent exhaust gases, the supercharged 6.2L HEMI engine uses the same free-flowing exhaust manifolds as found on the 6.4L/392 HEMI engines. These exhaust manifolds can also be used on other non-factory applications when dropping a GEN III HEMI engine into an older Mopar® car or truck. If you’re doing a swap using a supercharged 6.2L HEMI engine, it might be easier to go with an aftermarket long tube header as these will provide maximum performance. The aftermarket suppliers we have listed at the end of the story can help you with the proper header selection for the body/chassis you’re installing a GEN III HEMI engine into.
While it might be hard to locate a supercharged 6.2L HEMI engine from an SRT Hellcat, SRT Hellcat Redeye or SRT Demon, some do show up at swap meets and on Craigslist, but make sure you’re not buying an engine that came out of a stolen vehicle. Mopar does offer a complete brand-new 707-horsepower “Hellcrate” 6.2L HEMI engine. If your project needs more power, there’s the Mopar “Hellephant” crate engine that comes in at 426 cubic-inches and makes 1,000 horsepower. If you’re looking for something in-between, Mopar just released the 807-horsepower Hellcrate Redeye Supercharged 6.2L HEMI engine. Like all Mopar GEN III HEMI crate engines, they are available with an installation kit that includes a wiring harness, sensors and other components that make for a hassle-free installation. As always, there are numerous performance companies listed here that offer parts and even technical advice on GEN III HEMI engine installations in vintage Mopar vehicles.
Check out this gallery of supercharged GEN III HEMI engine swaps into cool vintage Mopar vehicles.