In 2015, Chrysler introduced a much anticipated HEMI reiteration in a 6.2 Liter displacement. This machine is the new frontrunner and will soon become the face of Chrysler’s one of many engine powerhouses.
By the time of its production, it was the most powerful engine Chrysler ever produced.
Later on, its overall efficiency, supercharging abilities, reliability, and appeal shows that it has a lot to offer.
But how does it line up with its other HEMI siblings? Let’s learn about the characteristics, overall engine design, and many more about the 6.2 HEMI engine.
What are Dodge HEMI 6.2 L Engines?
The HEMI 6.2 L engine is a high-performance supercharged variant of the HEMI engine family.
Inside the engine umbrella are duumvirates comprising the circle of the family – the 707-horsepower 6.2 Hellcat, which was named after the Grunman F6F Hellcat; and the 800-horsepower 6.2 L Demon that features several improvements from the Hellcat including components improvements, power, and torque increase.
In 2017, Mopar declared that it would sell the engine as a crate engine under the Hellcrate badge.
The high-performance division of Chrysler, SRT, did a fantastic job improving the quality of SRT8 cars, especially the 6.2L Hellcat. It was one of the most recognizable and powerful domestic engines out there, even in stock form, until the Dodge Demon was introduced.
Even with its celebrated status, some unearthed questions standstill for most Hellcat fanatics – how is it different from any other third-generation HEMIS?
However, some details regarding the engine cannot be found somewhere other than their press release. And with that, it took some time for them to wrap it up as the people outside the confinements of HEMI cliques are waiting for information like those.
Chrysler made it clear that Hellcat components are guaranteed 91 percent new but failed to address compatibility notes.
Engine Specifications and Design:
- Production Run: 2015 – Present
- Cylinder Head Material: Aluminum
- Cylinder Block Material: Cast-iron
- Configuration: V8
- Bore: 103.9 mm
- Stroke: 90.9 mm
- Valvetrain: OHV, two valves per cylinder
- Displacement: 6.2 L (6166 cc)
- Compression Ratio: 9.5
- Weight: 500 lbs.
- Maximum HP: 840 HP at 6,000 RPM
- Maximum Torque: 650 lb-ft at 4,000 RPM
The 6.2 HEMI Hellcat
The 6.2 L HEMI engine is obviously different from the Apache 6.4 L HEMI in terms of displacement. It adopted a combined bore and stroke dimension from the 6.4 HEMI and 5.7 HEMI, respectively.
Its cylinder bore is 103.9 mm; piston stroke is 90.9 mm, and a compression rating of 9.5 across all variants.
Having a shorter piston stroke is advantageous considering the block-deck height and connecting rod length used is from the 6.4 HEMI engine. One of those is the increase in compression height of the pistons.
To add to that, it also increases the crank overlap between the main journals and rod journals that overlap each other – enhancing the overall strength.
In a forced induction setup, having more piston material between the piston crown and wrist pin centerline creates more space for beefier ring land and allows the top ring to push farther down the bore.
In this way, it prevents the components from extreme cylinder pressure and heat generated through supercharging.
There are reports in extreme boost applications that they pushed the factory third-generation HEMI blocks to their limits, reaching a 1,000 HP mark – a pretty durable piece of cast iron.
The Hellcat also has a better cooling efficiency with a new and distinct water jacket geometry.
The increase in thermal loads demands better water flow around the top of the cylinder to regulate the temperature on the bore walls and head gaskets to prevent premature deterioration of such components.
The main bearings caps of both the 6.2 Hellcat and 6.4 Apache are the same.
The Hellcat crankshaft is identical to the forged ones of the Apache but with some enhancements to improve wear resistance as well as its overall impact on the performance. The crank journals are induction-hardened – a localized treating process for the entire crankshaft compatible with higher-load capacity bearings.
Furthermore, the crank fillets have an increased fatigue strength; the microgeometry and bearing clearances are optimized on the Hellcat Hemi crank. The carbon-coated pistons swing on floating pins for enhanced load resistance.
Since both the Hellcat and Demon are supercharged driven by a belt, it puts a tremendous amount of loads on the crank snout. Chrysler carried the Apache crankshaft to the Hellcat, providing the necessary drive torque for the supercharger.
The pulley bolt size has been increased by 2mm, and a diamond-coated washer between the crank and pulley offers a high friction coefficient.
As we mentioned earlier, the connecting rods and pistons of the Hellcat are new. As for the connecting rod, it is the same as Apache but has a different structure; and is made from a different alloy.
The DLC (Diamond-Like Coating) on the pistons reduces friction losses and increases the load-carrying capacity.
The 6.2 L HEMI heads shares the basic cylinder head architecture as the 6.4 HEMI Apache. 6.4 HEMI heads proved to be exceptional performers capable of flowing over 340 cfm.
However, on a side note, the difference between the 6.2 HEMI and 6.4 is it is suited with hollow-stem, sodium-filled exhaust valves capable of withstanding high temperatures up to 1475 Fahrenheit.
The 6.2 Hellcat is not equipped with Chrysler’s Multi-Displacement System (MDS) but utilizes lobe profiles similar to the hydraulic roller found in the 6.4L Apache.
However, the Hellcat intake lobes have a lesser lift and a couple of degrees less duration compared to Apache; but on the exhaust side, the Hellcat has 20-degrees more duration.
Though both engines have the same lobe-separation angle, the Hellcat features a different variable valve-timing map than the Apache.
Supercharging
The Hellcat, unlike other manufacturers, employs a twin-screw supercharger instead of the roots-style blowers. Roots style blowers build pressure against the sides of blower case contrary to the concept of twin-screw, which compresses the air between the rotors resulting in better adiabatic efficiency and less heat soak.
IHI builds Hellcat’s supercharger. Using an integrated electronic bypass valve, it displaces 2,380 cc and has a regulated boost pressure at 11.6 psi. The rotors feature a Teflon coating for tighter clearance, reduces internal air leaks, deeper efficiency increase, and corrosion resistance.
It has a premium synthetic lubrication with a 2.36 step-up ratio capable of up to 14,600 RPM.
The supercharger is hermetically assembled, perpetually sealed for the rest of its usage. The intercooler and its intake manifold are tightly packed into one integrated unit.
The air enters the 92 mm throttle body; it is compressed to continue its journey from the front of the supercharger rotors going up into the case, which serves as a plenum, before making a quick 180-degree detour down through the intake manifold runners and eventually to the cylinder heads.
Inside the chambers are two intercooler cores installed on each side of the supercharger housing that vitally double as the intake manifold runners. Located behind the air vents on both sides of the front bumper cover are dual heat exchangers for the intercooler fluid.
Chrysler’s test results regarding the intercooler system invigorated new confidence in the innovation they made. It revealed that the intercooler system could keep the intake air temperature below 140 degrees under the harshest conditions.
In addition, Hellcat’s power did not drop one bit even after a 20-lap course on a 3.1-mile road in a 100-degree heat setting.
The 6.2 HEMI Hellcat is rated at 797 HP at 6,000 RPM and 650 lb-ft of torque at 4,000 RPM. In 2019, under the hoods of Dodge Challenger, Chrysler released a Redeye version with 797 HP.
Applications of 6.2 L HEMI Hellcat:
- 2015 – Present Dodge Challenger SRT Hellcat
- 2015 – Present Dodge Charger SRT Hellcat
- 2018 – Present Jeep Grand Cherokee Trackhawk
- 2021 Dodge Durango SRT Hellcat
- 2017 RAM 1500 Rebel TRX Concept
- 2021 – Present RAM 1500 TRX
The 6.2L Demon
Before Demon’s arrival on the stage, Hellcat was considered superior in power above any Chrysler engine. However, tables have been turned, and Chrysler released a much-improved version of the Hellcat, the Demon.
It has the same displacement, almost identical to the Hellcat for sure, but it features a considerable number of improvements over the Hellcat. It has a larger 2.7 L twin-screw supercharger, a new camshaft, reinforced reciprocating components, and other valvetrain upgrades.
With these upgrades, the Challenger SRT Demon is rated at a staggering 808 HP on 91-octane pump gasoline and 840 HP when running on 100-octane unleaded racing gasoline.
The engine cooling is done via an Air-Grabber hood scoop and a unique charge cooling system that uses the air-conditioning coolant to lower the intake air charge temperature.
High-speed launches are factory line-lock system assisted, allowing the car to perform a massive burnout to warm the rear tires – the first transmission brake system installed in a production vehicle, and Torque Reserve Launch System.
6.2 Demon engines appeared in the 2018 Dodge Challenger SRT Demon.
Engine Tuning, Potential, and Modifications:
The 6.2 L Hellcat is easy to tune, to be honest, since it is not equipped with direct gasoline injection. Anybody can attest how hard it is to deal with factory direct-injection tuning – though some shops did, many failed.
Chrysler Engineers, on the other hand, say that Hellcat’s ECU is locked from the factory. So it will take a while to maneuver the Hellcat ECU.
In terms of swapping.
Chrysler paparazzi asked if the Hellcat will be offered as a crate motor; they said they cannot comment on it right now due to some strategic reasons. So don’t lose hope cause that might be a hint of a possible Hellcat crate engine release.
Moreover, the cylinder heads of 6.2 Hellcat and 6.4 Apache are similar to making the supercharger available for 6.4 HEMI bolting.
The only doubt is how the revamped water-jacket passage on the Hellcat cylinder heads works with the earlier third-generation HEMI blocks since it has the same bell housing patterns and motor mounts. Make sure to have ample room for the intercooler heat exchangers.
Problems Surrounding 6.2 L HEMI Engines:
The 6.2 HEMIs are pretty badasses in terms of their overall reliability. It has forged pistons, is capable of withstanding high power production, and can adapt in extreme conditions. But there are still weaknesses and shortcomings but not as major as it looks.
Some owners report the only issue is the supercharger bearings, but it is scanty and a tiny portion of the entire purchases conducted. It does not even affect 2% of the total number of vehicles produced. We addressed it here so you will have an idea regarding those bearings.
But apart from that, Hellcat is a sure-fire way to make your money’s worth. All of the owners are happy and enjoying their Hellcat and Demon monsters.
Summary:
The 6.2 L HEMI – Hellcat and Demon, even without the MDS (Multi-Displacement System), continued to compete among its peers. It is far more efficient than the earlier HEMI released; this is like the smoother version of the HEMIs combined. I know that’s debatable.
The improvements and overall innovation applied to the 6.2 HEMIs are top-notch, well-placed, and satisfying. Chrysler significantly improved the production of HEMIs throughout the years, reflecting on the product they showcased.
Better cooling system, intercoolers, and nasty superchargers. On top of non-existent issues or problems.
It is also swap-friendly and can be a great engine to have.