If you're looking to push your 392 to its absolute limit, a 6.4 hemi hellcat supercharger kit is probably the first thing on your radar. It makes sense, right? You've got the big displacement of the 6.4L Hemi, but you're missing that iconic whine and the neck-snapping torque that comes from the Hellcat's factory forced induction. It's the ultimate "what if" for Scat Pack and SRT 392 owners who want to bridge the gap between their naturally aspirated daily and a full-blown track monster.
But before you go out and buy the first kit you see, there's a lot to unpack. We aren't just talking about bolting on some parts and calling it a day. Swapping a Hellcat blower onto a 6.4 engine is a bit of a science project, and if you don't do it right, you might end up with a very expensive paperweight sitting in your driveway.
Why Everyone Wants This Setup
Let's be real for a second. The 392 Hemi is a fantastic engine. It's got soul, it sounds incredible, and it's plenty fast for most people. But once you've owned one for a year or two, you start to get used to the power. You start looking at those Hellcats at the stoplight with a bit of envy. The problem is, trading in a Scat Pack for a Hellcat can be a massive financial leap.
That's where the 6.4 hemi hellcat supercharger kit comes in. It offers a way to get that genuine Mopar factory feel without having to sell a kidney. There's something special about using OEM parts—or at least parts designed to mimic the OEM setup—to make more power. It feels "right" in the engine bay. Plus, that IHI supercharger whine is legendary. It's not just about the speed; it's about the experience of hearing that blower spool up when you mash the throttle.
What's Actually in the Kit?
You can't just take a supercharger off a Hellcat and bolt it directly onto a 6.4. The heads are different, the port shapes don't match up perfectly, and the belt drive system is a completely different animal. When you buy a conversion kit, you're usually getting a package that solves these "math problems" for you.
Usually, a solid 6.4 hemi hellcat supercharger kit includes the 2.4L or 2.7L IHI supercharger itself, but the magic is in the adapter plates. These plates allow the Hellcat manifold to sit properly on the 6.4 heads. You'll also need a custom fueling setup, including larger injectors and a high-flow fuel pump, because the stock 6.4 system simply can't keep up with the demands of forced induction.
Then there's the cooling. Hellcats use an air-to-water intercooler system with its own dedicated radiator and pump. A good kit will include all those hoses, the reservoir, and the heat exchanger to keep your intake air temperatures (IATs) from skyrocketing. If you skip the cooling, you're just asking for heat soak and pulled timing.
The Piston Problem (The Big Warning)
I have to be honest with you here: the 6.4 Hemi wasn't exactly built for boost. While the Hellcat engine (the 6.2L) has forged internals and lower compression, the 6.4 has cast pistons and a higher compression ratio. The top ring lands on the 6.4 pistons are notoriously thin.
If you slap a 6.4 hemi hellcat supercharger kit on and try to run 12 pounds of boost on a stock bottom end, you're playing a dangerous game. Most tuners recommend staying around 6 to 7 psi of boost if you're running on pump gas. At that level, you're looking at around 550 to 600 rear-wheel horsepower, which is a massive jump from the stock 410-ish. It's enough to make the car feel completely different without turning your pistons into glitter.
If you want more than that, you really need to look into "drop-in" forged pistons and rods. It's an extra expense, but it's a lot cheaper than buying a whole new engine after a catastrophic failure.
Driving Mechanics and the "Whine"
Once it's installed, the first thing you'll notice—besides the power—is the sound. There is absolutely nothing like the sound of a 6.4 hemi hellcat supercharger kit at wide-open throttle. It's a mechanical scream that lets everyone know you aren't running a stock setup.
The power delivery is also incredibly linear. Unlike a turbocharger that needs to "spool up," the supercharger is belt-driven, meaning the boost is right there as soon as you touch the pedal. In a heavy car like a Charger or Challenger, that low-end torque is exactly what you need to get all that weight moving. It makes the car feel 500 pounds lighter than it actually is.
Is It Better Than an Aftermarket Blower?
This is the big debate in the Hemi community. Should you go with a 6.4 hemi hellcat supercharger kit or something like a Whipple or a ProCharger?
The ProCharger is a centrifugal setup, which is easier to install and runs cooler, but you don't get that instant low-end grunt or the classic "top-mount" look. A Whipple is a beast and can arguably make more power than the Hellcat blower, but it also costs a premium.
The reason people stick with the Hellcat kit is the OEM integration. It looks like it belongs there. If you open your hood at a car show, seeing that Hellcat lid sitting on top of a 392 engine just looks cool. It's got a "factory-plus" vibe that aftermarket units sometimes lack. Plus, if you're resourceful, you can sometimes find used Hellcat blowers for a decent price and just buy the installation kit separately to save some cash.
Tuning and Support
Don't even think about finishing the install and driving to the grocery store without a proper tune. Your car's computer (the PCM) has no idea what to do with the extra air coming into the engine. You'll need to have your PCM unlocked and a custom tune written specifically for your setup.
Modern Hemis are sensitive to tuning. You want someone who knows these engines inside and out. A bad tune will destroy your engine faster than any amount of boost ever could. Most 6.4 hemi hellcat supercharger kit retailers will offer a "canned tune" to get you started, but I'd always recommend getting a professional dyno tune or a reputable email tune to make sure your air-fuel ratios are safe and your timing isn't too aggressive.
The Bottom Line
Putting a 6.4 hemi hellcat supercharger kit on your ride is one of the most rewarding mods you can do. It transforms the car from a quick cruiser into a legitimate powerhouse. However, it's not something you should rush into. You've got to respect the limits of the 6.4 engine, keep the boost at a sensible level, and make sure your fueling and cooling are up to the task.
If you do it right, you'll have a car that sounds like a demon and pulls like a freight train. Just be prepared to buy a lot more rear tires, because once that blower is under the hood, your days of having traction are pretty much over. It's a small price to pay for that much fun, though, don't you think?