Part 2 - The Hemi Engine: Under the Hood and Decoding the Hemi Engine Dynasties

Under the Hood: Decoding the Hemi Engine Dynasties

We've talked about the Hemi's history, now it's time to get our hands dirty. We're going deep under the hood of the modern Hemi lineup: the 5.7L, 6.4L, Hellcat, Demon, and Hellephant. It's not just about specs—we're talking about what makes these engines tick (sometimes literally!), what enthusiasts love about them, and what to watch out for.

Okay, let's revamp that section on the 5.7L Hemi, blending the provided information more organically, keeping the engaging tone, and adding more specific details and context:

The Everyday Powerhouse: 5.7 Liter Hemi - The Engine That Reborn a Legend

The 5.7L Hemi—this engine is where the modern Mopar story really takes off. When Chrysler unleashed it in 2003, it wasn't just another V8; it was a resurrection. It marked the return of the Hemi name, and it did it in a way that perfectly balanced the demands of the 21st century with the spirit of the original. The 5.7 Hemi truly gave us a working-man's engine, reliable and easy to fix and document!

This wasn't your grandpa's gas-guzzler. Sure, it had the classic Hemi rumble and plenty of power—initially 345 horsepower in the Ram trucks, later rising to around 390-395 hp. But Chrysler engineers knew they had to do more than just crank up the displacement. They needed an engine that could deliver both performance and reasonable fuel economy, a seemingly impossible task for a V8.

Their solution was a multi-pronged approach. The 5.7L (345 cubic inches, or 5,654 cc to be precise) featured a cast-iron block for durability and two-valve aluminum heads with that signature hemispherical combustion chamber shape for efficient airflow. Early models (2003-2008) had a compression ratio of 9.6:1, but this was bumped up to 10.5:1 in 2009 and later for improved power and efficiency.

But the real ace up the 5.7L's sleeve was the Multi-Displacement System (MDS). This technology allowed the engine to seamlessly shut down four cylinders under light load conditions, like cruising on the highway. It was, in essence, a V8 that could act like a four-cylinder when you didn't need all that muscle. Clever, right?

The result was an engine that could deliver around 340-375 horsepower and 390-410 lb-ft of torque in passenger cars like the Dodge Charger R/T, Challenger R/T, and Chrysler 300C—more than enough to put a smile on your face. Yet, it was also surprisingly manageable in everyday driving, with decent fuel economy (for a V8, of course!).

This versatility is what truly made the 5.7L a hit with enthusiasts. You could haul lumber in your Ram 1500 during the week and cruise to a car show on the weekend, all with the same engine. It was the perfect blend of power, practicality, and—dare we say it—value. The new millenium of working class man. It was an engine that made sense, and that resonated with a wide range of buyers. It proved that the Hemi name wasn't just about nostalgia; it was about a modern, adaptable V8 that could do it all.

Specifications

• Displacement: 5.7 liters (345 cubic inches)

• Block: Cast iron

• Cylinder Heads: Aluminum with those signature hemispherical combustion chambers

• Compression Ratio: 9.6:1 to 10.5:1 (it varies a bit depending on the model)

• Fuel System: Multipoint fuel injection

• Key Features: Two spark plugs per cylinder, Multi-Displacement System (MDS) in some versions

Applications

Here's a more comprehensive list of vehicles powered by the 5.7L Hemi (thanks, Wikipedia, for helping me compile this!):

• 2003–present Ram Pickup 1500/2500/3500

• 2004–2009, 2011–present Dodge Durango

• 2005–2008 Dodge Magnum R/T

• 2005–present Chrysler 300C, 300S V8

• 2005–present Jeep Grand Cherokee

• 2006–2010 Jeep Commander

• 2007–2009 Chrysler Aspen

• 2009–present Dodge Challenger R/T

• 2005- Present Dodge Charger

Common Issues & Enthusiast Takes: The Good, the Bad, and the Tick

No engine is perfect, and even the beloved 5.7L Hemi has its share of quirks and potential problems. Let's be clear: the vast majority of 5.7L owners have a positive experience. But it's important to be aware of the common issues that do pop up, especially if you're buying a used Hemi-powered vehicle.

The most infamous issue, by far, is the dreaded "Hemi Tick." This is a ticking sound that emanates from the valvetrain, and it's the subject of endless online forum discussions and owner debates. The key is differentiating between a normal Hemi tick and a problematic one. Many 5.7L Hemis, particularly those with the Multi-Displacement System (MDS), exhibit a slight ticking sound at idle. This is often attributed to the injectors or the lifters cycling as the MDS system engages and disengages cylinders. In many cases, this light ticking is considered normal and doesn't indicate a serious problem. Think of it as a characteristic of the engine, not necessarily a flaw.

However—and this is a big however—a loud, metallic, persistent tick is a red flag. This often indicates a stuck lifter or, worse, a worn lifter roller that's starting to damage the camshaft. If ignored, this can lead to catastrophic engine failure, with metal shavings circulating through the oil system. The MDS lifters, in particular, seem to be sensitive to oil quality and maintenance. Sticking to the recommended oil change schedule (religiously!) and using the correct oil viscosity (typically 5W-20 for most 5.7L applications, though SRT versions may call for 0W-40) is absolutely crucial.

Beyond the tick, the MDS system itself can be a source of minor complaints. Some owners report a slight hesitation or vibration when the system transitions between eight-cylinder and four-cylinder mode. It's not a reliability issue, per se, but it can be an annoyance for some drivers. Some performance enthusiasts choose to disable the MDS system using aftermarket tuners, prioritizing consistent V8 power over the fuel economy benefits.

Finally, some 5.7L owners have reported higher-than-expected oil consumption. This isn't a universal problem, and it can often be mitigated by diligent maintenance. But it's something to be aware of and monitor regularly.

Overall Enthusiast Opinion: Despite these potential issues, the 5.7L Hemi remains a highly regarded engine. Its combination of power, relative affordability, and overall reliability makes it a popular choice for a wide range of vehicles. The "Hemi Tick" is a known concern, but proactive maintenance and a discerning ear can go a long way in preventing serious problems. The 5.7 is truly the reliable working-man's engine! It's the Hemi you can live with, and for many enthusiasts, that's the ultimate compliment.

Stepping Up the Performance: 6.4 Liter Hemi (392) - Big Power, Big Presence

The 5.7L Hemi is the everyday hero, the reliable workhorse. But what if you crave more? More power, more presence, more attitude? That's where the 6.4L Hemi, affectionately known as the "392" (its cubic-inch displacement), comes in. This isn't just a bigger 5.7L; it's a different beast altogether.

Think of the 6.4L as the 5.7L's wilder, more rebellious sibling. It's the engine for the serious performance enthusiast, the person who wants a Hemi that doesn't just rumble—it roars. And roar it does, with a deeper, throatier exhaust note that's pure American muscle car symphony.

But the 6.4L's upgrades go far beyond just sound. This engine, displacing 6,407 cc (392 cubic inches), is built to handle serious stress. It features a robust cast-iron block, like the 5.7L, but adds a forged steel crankshaft and hypereutectic aluminum pistons—components designed to withstand the higher combustion pressures and temperatures generated by this more powerful engine.

The 6.4L Hemi made its grand entrance in the 2011 Dodge Challenger SRT8, and it was immediately clear that this was something special. Early versions boasted a 10.9:1 compression ratio and pumped out an impressive 470 horsepower and 470 lb-ft of torque. But Chrysler didn't stop there. In 2015, for the Charger and Challenger Scat Pack and SRT models, the output was bumped up to a mighty 485 horsepower and 475 lb-ft of torque. (The Jeep Grand Cherokee SRT, however, retained the approximately 470 hp rating.)

Interestingly, there's also a slightly detuned version of the 6.4L used in Ram Heavy Duty trucks. This version, with a lower 10.0:1 compression ratio, makes around 410 horsepower, but it's tuned for better low-end torque—perfect for towing and hauling heavy loads. It's a testament to the versatility of the Hemi design that it can be tailored for both track-day thrills and work-truck duties.

This is the engine you want if you're serious about performance. It's not just about straight-line speed; it's about the feel of the engine, the way it responds to your right foot, the way it makes you grin every time you start it up. The 6.4L takes the best qualities of the 5.7L—the Hemi heritage, the strong power delivery—and amplifies them, creating an engine that's both exhilarating and (relatively) practical. It is all about the sound!

Specifications

• Displacement: 6.4 liters (392 cubic inches)

• Block: Cast iron with 4-bolt main caps

• Crankshaft: Forged steel

• Pistons: Hypereutectic aluminum

• Compression Ratio: 10.9:1

• Power Output:

• 485 hp / 475 lb-ft (Challenger SRT8, Charger SRT)

• 410 hp / 429 lb-ft (Ram 2500/3500)

• Peak RPM: 6,400

• Fuel: Premium is recommended, for a reason!

Applications

Here's a breakdown, drawing inspiration from those dedicated Wikipedia editors:

• 2011–2023 Dodge Challenger SRT 392

• 2005–2010 Chrysler 300C SRT8

• 2012-2014 Dodge Charger SRT8 Super Bee

• 2006–2010 Jeep Grand Cherokee SRT8

• 2014–present Ram 2500

• 2013–present Ram 3500

• 2015–2022 Dodge Charger SRT 392

• 2015–2018 Dodge Challenger SRT 392

Common Issues & Enthusiast Takes

• MDS Issues (Again!): Yep, the 6.4L also has MDS, and it can have similar problems to the 5.7L. Some owners choose to disable it with a tuner.

• Camshaft/Lifter Failures: Just like the 5.7L, lubrication is key. Sticking to the recommended oil (0W-40 synthetic) and changing it regularly is crucial.

• Piston Slap: This seems to be less common than the "Hemi tick," but some owners have reported a piston slap noise, especially on cold starts.

Overall Enthusiast Opinion: The 6.4L is a beast. It's not quite as refined as the 5.7L, but that's part of its charm. It's raw, powerful, and sounds incredible. If you're serious about performance, this is a great choice.

Unleashing the Supercharged Beast: Hellcat Engine (6.2 Liter) - Welcome to the Mopar Madhouse

Forget "stepping up"—the Hellcat engine is a whole different dimension of performance. When Dodge unleashed this supercharged 6.2L V8 in 2015, it wasn't just introducing a new engine; it was making a statement. 707 horsepower in a factory-built muscle car? It was, frankly, ludicrous. And that's precisely why it became an instant legend.

The Hellcat is where Dodge threw out the rulebook and embraced glorious excess. This isn't just about going fast; it's about the experience. It's about the primal scream of that 2.38-liter IHI twin-screw supercharger, force-feeding the engine with 11.6 psi of boost. It's about the brutal acceleration that pins you to your seat and makes your vision blur. It's about a car that's almost too much, and that's exactly the point.

Technically speaking, the Hellcat shares its bore with the 6.4L Hemi and its stroke with the 5.7L, resulting in a displacement of 6,166 cc (roughly 376 cubic inches). But those numbers don't tell the whole story. This engine features a lowered compression ratio of 9.5:1 to handle the forced induction, and it's packed with strengthened components to cope with the immense power. And that power? A staggering 707 horsepower at 6,000 rpm and 650 lb-ft of torque at 4,000 rpm, straight from the factory. This made the Hellcat one of the most powerful production muscle car engines ever at its launch, and it sent shockwaves through the automotive world. And even better... there were more powerful engines after it was released.

Interestingly, Dodge chose not to include the Multi-Displacement System (MDS) on the Hellcat. This engine is all about maximum power, all the time. And frankly, when you have 707 horsepower on tap, who needs cylinder deactivation?

Enthusiasts don't just like the Hellcat; they revere it. It's the engine that proved Dodge hadn't lost its edge, that it still had the audacity to build something truly outrageous. It was a defiant roar in an era of downsizing and efficiency, a reminder that sometimes, more is more. It was a middle finger to convention, and Mopar fans loved it for that. The sound... is absolutely, and perfectly, loud.

Specifications

• Displacement: 6.2 liters (376 cubic inches)

• Power Output:

• 707 hp / 650 lb-ft (standard Hellcat)

• 717 hp-807 hp (Hellcat various models)

• Block: Cast iron with enhanced cooling

• Crankshaft: Forged steel

• Pistons: Forged

• Compression Ratio: 9.5:1

• Peak RPM: 6,200

• Fuel: Premium. Don't even think about putting anything else in it.

Applications

Compiling the list, leveraging community knowledge and resources like Wikipedia:

• 2015–2023 Dodge Challenger SRT Hellcat

• 2015–2023 Dodge Charger SRT Hellcat

• 2018–2021 Jeep Grand Cherokee Trackhawk

• 2021 Dodge Durango SRT Hellcat

• 2021–present Ram 1500 TRX

Common Issues & Enthusiast Takes

• Supercharger Bearing Failures: This is the big one. Those supercharger bearings can fail, and it's an expensive repair. Some owners have had multiple failures.

• Battery Drain: The Hellcat's electronics can be a bit finicky, and some owners have reported unexpected battery drain.

• Oil Consumption: Like the other Hemis, it's important to keep an eye on the oil level.

• It can attract too much attention: Many fans talk about how much attention driving it on the street is, as people want to always see what it can do.

Overall Enthusiast Opinion: The Hellcat is a legend. It's not perfect, but its flaws are almost part of its charm. It's a wild, untamed beast of an engine, and that's why people love it.

The Drag Strip Dominator: Demon Engine (6.2 Liter – Hellcat, Unleashed)

If the Hellcat is a beast, the Demon engine is a mythical creature. It's not just a tuned Hellcat; it's a Hellcat that's been to the dark side and come back with a vengeance. Dodge's mission was clear: build the ultimate factory drag car, a machine so extreme that it would rewrite the rules of street-legal performance. And they succeeded, spectacularly.

The Demon isn't just about more power (though it has plenty of that, believe me). It's about a relentless focus on quarter-mile domination. Every detail, every component, was scrutinized and optimized for one purpose: to launch like a rocket and obliterate the competition.

The heart of the beast is still a 6.2-liter supercharged Hemi, but it's been significantly upgraded. The supercharger is bigger—a massive 2.7-liter unit compared to the Hellcat's 2.38-liter—and it pumps out even more boost. The internals, including the connecting rods and pistons, were strengthened to handle the increased stress. The valvetrain was also beefed up to cope with the higher engine speeds.

But the magic of the Demon isn't just in the engine; it's in the whole package. Dodge included a TransBrake, a feature typically found only in dedicated drag cars, which allows for incredibly aggressive launches. The suspension was specifically tuned for drag racing, with softer springs and adaptive dampers that optimize weight transfer. Even the air conditioning system was repurposed to chill the intake air, squeezing out every last bit of horsepower.

And the numbers? Staggering. On 91-octane pump gas, the Demon engine produces a mind-blowing 808 horsepower. But feed it 100+ octane race fuel and unlock the factory Stage II kit, and you're looking at a monstrous 840 horsepower and 770 lb-ft of torque. This made the Demon the first-ever production car to break the 800 horsepower barrier on pump gas. The compression ratio, interestingly, remained similar to the Hellcat's, around 9.5:1, demonstrating the effectiveness of the supercharger and other enhancements.

Then, a few years later the Demon 170 came out. Cranking over 1000HP! It was incredible, Dodge really produced some of the most legendary and historic engines in only a few short years.

Enthusiasts don't just admire the Demon; they worship it. It's a car that can run 9-second quarter-mile times straight from the factory, a feat that was once the exclusive domain of heavily modified race cars. It's a limited-production, purpose-built machine, a testament to Dodge's commitment to pushing the boundaries of performance. It's a rolling middle finger to physics, a car that shouldn't exist but does, gloriously.

Specifications

• Displacement: 6.2 liters (376 cubic inches)

• Power Output:

• 808 hp (Demon on pump gas)

• 840 hp (Demon on 100+ octane race gas)

• 900 hp (Demon 170 on E10, a blended fuel)

• 1,025 hp (Demon 170 on E85)

• Block: Cast iron

• Cylinder Heads: Aluminum alloy

• Compression Ratio: 9.5:1

• Redline: 6,500 rpm

• Fuel: Premium or race gas/E85 for peak performance.

Applications

• 2018 Dodge Challenger SRT Demon

• 2023 Dodge Challenger SRT Demon 170

Common Issues & Enthusiast Takes

• Engine Failures: It is an engine pushed to the max. It has happened on occassion.

• Supercharger Woes: Same as the Hellcat—those bearings can be a problem.

• It's Addicting: People love to see just how fast this thing can do on the street and race track!

Overall Enthusiast Opinion: The Demon is the ultimate expression of the Hemi's potential.

The Ultimate Crate Engine: Hellephant (426 ci) - A Modern Legend, Unleashed

The Hellephant isn't just an engine; it's a statement. It's a "what if" scenario brought to life, a love letter to Mopar history and a defiant roar into the future. Imagine taking the legendary 426 Hemi, the "Elephant Engine" that dominated the muscle car era, and giving it a 21st-century makeover—a supercharged, all-aluminum, 1,000-horsepower makeover. That's the Hellephant.

This isn't an engine you'll find in a production car. It's a crate engine, sold by Mopar Performance, designed for the ultimate custom build. It's for the enthusiast who dreams of dropping a modern-day monster into a classic chassis, creating a restomod that's both a tribute to the past and a celebration of cutting-edge performance. It's about building a classic, and reliable car. And you know Mopar's documentation will assist every step of the way.

The name itself is a perfect blend: "Hellcat" (representing the supercharged power) and "Elephant" (a nod to the original 426 Hemi's nickname). And the engine lives up to the name. We're talking about a fully forged, all-aluminum block displacing a massive 426 cubic inches (7.0 liters). Atop that sits a 3.0-liter supercharger, force-feeding the engine to produce a staggering 1,000 horsepower and 950 lb-ft of torque.

Those numbers are almost absurd. This is an engine that can transform a classic muscle car into a modern-day supercar slayer. It runs a 9.5:1 compression ratio, similar to the Hellcat and Demon, and Mopar recommends a maximum of 6,800 rpm on premium fuel.

The Hellephant isn't just about raw power; it's about bringing that power to your project. Mopar even offers a kit to help enthusiasts swap this beast into pre-1976 vehicles, as demonstrated by the stunning 1968 Charger concept car that debuted alongside the engine.

This engine represents the pinnacle of Mopar performance, a blend of heritage and cutting-edge technology. It's a dream engine, a fantasy made real, and a testament to the enduring appeal of the Hemi legacy. It also proves Mopar will always give value!

Specifications

• Displacement: 426 cubic inches (7.0 liters)

• Power Output: 1,000 hp / 950 lb-ft

• Block: Aluminum

• Cylinder Heads: Aluminum

• Supercharger: 3.0 liters

Applications

• Custom Builds: That's it. This is a crate engine, meant to be dropped into whatever you can dream up.

Common Issues & Enthusiast Takes

• Not much really! Because the engines get dropped into so many things, the Hellephant specific issues is very minor.

Overall Enthusiast Opinion: If you can get your hands on one, you are very lucky.

Common Issues and Enthusiast Feedback: The Hemi's Underbelly

No engine, no matter how legendary, is completely without its quirks and potential problems. The modern Hemi family, while generally robust and powerful, has its share of common issues that enthusiasts and owners frequently discuss. Understanding these potential problems is key, whether you're a current owner, a prospective buyer, or just a curious enthusiast.

1. The Infamous "Hemi Tick": This is, without a doubt, the most discussed issue across the 5.7L and 6.4L Hemi communities. It's a ticking sound, typically emanating from the valvetrain, and it can range from a barely audible annoyance to a serious cause for concern. The crucial distinction is between a normal Hemi tick and a problematic one.

• Normal Tick: Many HEMI engines simply tick on startup. Some have said it's due to the oil, or exhaust manifold spacing which will close up upon warmup. This light ticking is generally considered normal and doesn't indicate a mechanical problem. It's often described as a characteristic of the engine, a quirk that many owners learn to live with.

• Problematic Tick: A loud, persistent, metallic tick, however, is a warning sign. This often indicates a stuck lifter, a worn lifter roller, or even damage to the camshaft itself. If ignored, this can lead to catastrophic engine failure, with metal shavings circulating through the oil system. The MDS lifters, in particular, are known to be sensitive to oil quality and maintenance.

The consensus among enthusiasts and mechanics is clear: regular oil changes with the correct viscosity (typically 5W-20 for most 5.7L applications, 0W-40 for the 6.4L and SRT models) are absolutely crucial for preventing lifter and camshaft problems. Sticking to the manufacturer's recommended maintenance schedule is the best defense against the dreaded "Hemi Tick."

2. Multi-Displacement System (MDS) Concerns: While MDS is a clever technology designed to improve fuel economy, it's not without its detractors. Some owners report a noticeable hesitation or vibration when the system transitions between eight-cylinder and four-cylinder modes. This isn't necessarily a sign of a mechanical problem, but it can be an annoyance for some drivers.

More seriously, there's a widespread belief among enthusiasts that the constant cycling of the MDS lifters can contribute to premature wear, potentially exacerbating the "Hemi Tick" issue. While there's no definitive proof of a direct causal link, many performance-minded owners choose to disable the MDS system using aftermarket tuners. This prioritizes consistent V8 power and eliminates any potential risk associated with MDS, even if it means sacrificing a bit of fuel economy.

3. Supercharger Woes (Hellcat and Demon): The supercharged Hellcat and Demon engines are generally robust in terms of their internal components, but the supercharger itself has been a source of issues, particularly in early models.

• Bearing Failures: Owners of 2015-2016 Hellcats frequently reported a rattling or grinding noise from the supercharger at idle, indicating a failure of the front bearings. This was a widespread enough problem that Dodge quietly redesigned the supercharger (manufactured by IHI) around 2016-2017, changing the bearing design and/or supplier. While no formal recall was issued, many early Hellcats had their superchargers replaced under warranty. The issue was largely resolved in later models, but it's something to be aware of if you're considering an older Hellcat. The Demon engine saw very little of this issues.

• The Demon 170 engines are new and haven't seen many real issues that effect performance.

4. Exhaust Manifold Bolt Breakage (5.7L and 6.4L): This is a more mechanical, less "characteristic" issue. The exhaust manifold bolts, particularly the rearmost ones, on the 5.7L and some 6.4L Hemis are prone to breaking. This is often attributed to the exhaust manifold warping due to heat cycles, putting stress on the bolts. The resulting exhaust leak can create a ticking sound that's often mistaken for the "Hemi Tick," leading to misdiagnosis. The fix is relatively straightforward—replacing the broken bolts and, if necessary, the warped manifold—but it can be a labor-intensive job.

5. Maintenance Quirks: The Hemi's dual spark plug design means 16 spark plugs to replace, which can be a more time-consuming and costly maintenance item. Owners also report that the spark plugs tend to wear out relatively quickly (around 30,000 miles), requiring more frequent replacement.

6. Hellephant Feedback is all positive. It should also be noted, because it is technically a "race" engine, Mopar offers it with no warrenty.

Overall: The modern Hemi family, while powerful and generally reliable, has its share of known issues. The "Hemi Tick" is the most pervasive and potentially serious, but diligent maintenance and a discerning ear can go a long way in preventing major problems. The supercharger bearing issue on early Hellcats is also a significant concern, but it was largely addressed in later models. The other issues are generally more manageable and less likely to lead to catastrophic failures. Despite these quirks, the Hemi remains a beloved engine family, prized for its power, sound, and enduring legacy.

Closing Thoughts on the Hemi Dynasties

So there you have it—a deep dive into the modern Hemi family, from the everyday workhorse 5.7L to the fire-breathing Hellephant. Each engine has its own personality, its own strengths, and its own quirks. It's a testament to the enduring appeal of the Hemi that it can be so many things to so many people—a reliable daily driver, a weekend track weapon, or a blank canvas for custom builds. What really makes these engines special is the community around them, the enthusiasts who keep the Hemi spirit alive. But the automotive landscape is changing fast. The rumbling sounds that many know is soon fading. So, what does the future hold for the Hemi in a world of tightening emissions and the rise of electric power? That's what we'll tackle next, in Part 3...