Exploring the Legacy: The Evolution of Chrysler’s 6.4L Hemi Engine in Trucks

We are living the last golden hours of the 6.4L Hemi V-8 Engine

With the constant war waging against the internal combustion engine by the electric car, there are increasingly less and less reasons you can argue on why these dinosaur machines should stick around. At any rate, we should enjoy them while they are here. So, over the next few weeks we will be covering the history and background of the best 6.4 V-8 Hemi truck engines on the market so you can go get one now, and have fun while you can.

Chrysler’s Hemi Engine History

Up until 2002, Chrysler had offered the 8.0L Magnum V-10 engine, producing 300 hp and 450 lb-ft of torque. A monster of a gasoline engine, it rivaled the 5.9L Cummins engines available at the time In both horsepower and torque up until the end when the Cummins surpassed its torque output by a mere 10 lb-ft of torque.

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Ending in 2002, Chrysler had no large displacement gasoline engine as an alternative to the Cummins available in any of their trucks.

Starting in 2014, Chrysler engineers debuted the new 6.4L Hemi engine, code named Apache.

The 6.4L Apache displaces 392 cu-in, and as a medium-duty commercial truck option, falls in line with the 6.7L Cummins medium-duty rating, as well. Pulling from Chrysler’s long history of engines, going all the way back to World War II, the Apache features high end durability enhancements.

Receiving upgrades in the form of tough alloy exhaust valve seats, sodium-filled exhaust valves, aircraft grade stainless steel gaskets and fasteners, and a high-efficiency and high-flow oil cooling system with piston jets and an oil cooler designed with the aid of computational fluid dynamics.

All forged internals, with a cast iron block, cross bolted main-bearing caps, and 356 aluminum—and the list keeps going and going.

Cylinder Head Construction: The Heart of Durability

One question that pops up again and again among Hemi enthusiasts: Are all 2011 and newer 6.4L Hemi engine cylinder heads built from T356 aluminum?

The answer is yes—across the board, Chrysler spec’d out solid 356-T6 aluminum alloy for these heads, regardless of whether you find them in a truck, muscle car, or SUV.

Why does this matter?

This particular alloy is prized in the automotive world for its blend of strength, lightweight properties, and resistance to heat, making it perfectly suited to endure the strains of modern high-compression V-8 life.

Some folks might recall the era when cylinder heads were an iron-heavy affair, but the 356-T6 aluminum formulation is a serious upgrade.

Not only does it keep weight in check for better handling (not that your Ram 2500 is chasing apexes), but it shrugs off the relentless cycles of heat and pressure these powerhouses produce.

This move to robust alloy construction pairs perfectly with the Hemi’s performance intent—providing a solid platform for those hollow-stem intake valves, sodium-filled exhaust valves, and all the other gear that sets the 6.4L apart from your run-of-the-mill truck engine.

So no matter which Hemi you’re eyeing from the 2011 model year and onward, you’re getting a set of cylinder heads forged from the same tough, heat-battling material—a detail that further cements the engine’s legacy of strength and reliability.

Cylinder Head Specs: Car/SUV vs. Truck Variants

So, aside from that robust aluminum foundation, what else distinguishes these Hemi cylinder heads, particularly when you compare car/SUV versions to their truck counterparts? Here’s the inside scoop on what’s lurking beneath those massive valve covers.

Casting Numbers & Variants

For cars and SUVs (think Dodge Challenger, Charger, and Jeep Grand Cherokee SRT), you’ll typically spot casting numbers like 5037369BD and 68166435AA-A02 stamped into the head.
Trucks (Ram 2500 and up) show their own lineage with identifiers such as 05045468AE and additional versions like 68166435AA, AB, AC, or AD.

Construction Details

All 2011+ 6.4L Hemi cylinder heads use the same tough-as-nails 356-T6 aluminum. This means you’re getting premium material whether you pull the engine out of a muscle car or a workhorse pickup.

Combustion Chamber & Ports

Chamber volume: 74cc across the board, designed for that sweet spot between efficiency and performance.
Intake ports: Feature a square shape for maximized airflow—yes, even on the heavy-duty truck heads.
Exhaust ports: Sport a “D” shape, engineered for improved gas scavenging.

Valve Arrangement & Specs

Intake valves: 2.14” diameter, hollow-stem design—lightweight and built for high-rpm breathing.
Exhaust valves: 1.65” diameter, hollow-stem, and sodium-filled for supreme heat resistance—just the ticket for those punishing, repeated pulls.

Fasteners & Plugs

Cylinder head bolts: Torque-to-yield (TTY) style, sized at M12 x 1.5mm along with 8mm for precise clamping force.
Spark plugs: Standard 14mm threads, gasketed, with a 1.043” reach and projected nose—activation relies on a 5/8” socket.

With these elements at play, every 6.4L Hemi head—no matter what badge is on the fender—delivers the resilience and performance legacy the platform is known for.

Camshaft Specs for the 2011+ 6.4L Hemi Apache Engine

Chrysler didn’t just pull the 6.4L Hemi out of a magician’s hat—the camshaft in this Apache engine is a carefully tuned centerpiece built for both muscle and finesse. Here’s the rundown:

Duration (at 0.050” lift): 221 degrees intake, 225 degrees exhaust—striking a solid balance between low-end grunt and high-rpm breathing.
Lobe Separation Angle: 114 degrees, engineered for a smooth idle and excellent airflow throughout the rev range.
Valve Lift: 0.571” on intake, 0.536” on exhaust, allowing those big valves plenty of room to flex their muscles.
Variable Cam Timing (VCT): Yes, courtesy of Chrysler‘s hydraulic cam phasing, giving you a wider torque band and cleaner emissions.
Multiple Displacement System (MDS): Active only in vehicles equipped with automatic transmissions, helping to sip fuel when you don’t need all eight hungry cylinders roaring.
Cam Journal Diameter: Bulky 57mm at the front (narrowing at the rear)—a testament to the beefy construction needed for workhorse duty.

The end result? A cam profile that doesn’t compromise, delivering brawny output for heavy haulers while keeping things civilized for daily driving duty.

Camshaft Variations: Automatic vs. Manual Transmission

Here’s where things get interesting for the shift-it-yourself crowd. If you’ve been digging through spec sheets, you might have noticed some confusion around cam profiles—especially when it comes to how they differ between automatic and manual transmission 6.4L Hemis.

So, are there differences in camshaft specs between auto and manual versions?

Yes, but only in a specific context: the Multiple Displacement System (MDS). This cylinder-deactivation tech—a clever bit of engineering that lets your Hemi run on four cylinders for fuel savings—shows up exclusively in vehicles equipped with automatic transmissions. Because the MDS system relies on variable cam timing and specific cam profiles, engines paired with automatics get a slightly different camshaft designed to work in harmony with MDS.

Meanwhile, manual transmission versions skip the MDS entirely, running a non-MDS cam profile. The main physical specs—duration, lift, and lobe separation—remain nearly identical between the two, but the underlying cam design varies just enough to accommodate the presence or absence of MDS.

To sum up:

Automatic transmission: Features MDS, so the camshaft is tailored for cylinder deactivation.
Manual transmission: Runs a non-MDS cam profile, since MDS isn’t available.

Still, both versions retain the signature 6.4L cam attributes—meaning whether you row your own gears or let the computer do the work, you’re getting a cam setup tuned for big torque and robust street manners.

Decoding the BGE and BE Casting Marks

If you’ve ever taken a closer look at the 6.4L Hemi block, you might spot the casting marks “BGE” or “BE” tucked away on the iron.

Here’s the translation:

“BGE” stands for Big Gas Engine – a designation Chrysler reserves for blocks destined for heavier duty use, like Ram trucks or vehicles needing extra durability under load.

On the other hand, you’ll find the “BE” marking on car-oriented Hemi blocks, such as those found in the Dodge Challenger and Charger.

The two variants share plenty of robust engineering DNA, but the BGE block typically features subtle reinforcements, ready to stand up to the demands of trucks towing trailers or hauling payloads. Think of the BGE block as wearing a pair of steel-toed boots, just in case the job calls for maximum muscle.

Competing with Cummins

An active dual-runner-length intake manifold, that boosts both low and high end power by maximizing the natural supercharger effect of the manifold, and a 10.9:1 compression ratio gives this big engine 410 hp and 429 lb-ft of torque.

Variable valve timing through the use of a hydraulic cam phasing system, ensures that the engine, despite running on mid-grade 89 octane fuel for maximum output, can run seamlessly on regular gasoline.

The extra plug fires during the power stroke to more fully burn the fuel in the cylinder, which provides more power in the down stroke and also numbers the amount of catalyst plates needed In the exhaust system.

This also has the benefit of allowing the primary spark plug to fire closer to top dead center, increasing torque and cutting NOx emissions.

Let’s talk about the heart of the 6.4L Hemi’s breathing system.

Chrysler equipped this engine with a composite “active” intake manifold sporting variable-length runners – a clever setup that lets the engine adapt for both low-end torque and high-RPM power.

This innovation is no afterthought; it’s the kind of engineering you’d expect from a company chasing both muscle and efficiency.

The throttle body is no slouch, measuring in at a hefty 80mm with a sturdy four-bolt mounting pattern. It’s fully electronically controlled, ensuring crisp throttle response whether you’re pulling a trailer or just having a little fun off the line.

Fuel delivery is handled by different injectors depending on application. Car and SUV versions of the 6.4L Hemi use 27 lb/hr injectors at 58 PSI, while the medium and heavy-duty truck variants step up to 31 lb/hr injectors at the same pressure.

Both make use of modern USCAR EV6 connectors for reliability and ease of service, though neither is flex-fuel capable straight from the factory.

This collection of components ensures the 6.4L Hemi breathes deep, burns clean, and delivers the kind of punch you’d expect from a descendant of Chrysler’s legendary engine lineup.

Tuning and Torque Curve Quirks

Now, if you’ve spent any time in Hemi forums or behind the wheel of a 6.4L-equipped machine, you’ve probably heard chatter about the engine’s torque curve—especially when it comes to the variable intake system.

One of the most common questions folks ask is about the stock cam’s power band. In most 6.4L Hemi applications, especially in performance trims like the Challenger R/T Scat Pack, you’ll see peak horsepower arriving near the 6,000-6,400 RPM mark. However, the sweet spot for torque tends to live a bit lower, typically pulling strong from around 4,000 up to 6,100 RPM.

But here’s where things get interesting: there’s a known dip in the torque curve, often hovering around 4,600 RPM. What’s behind this little valley? It’s the timing of the variable intake runner system. As the runners swap from long to short to favor high-RPM breathing, the electronics sometimes transition a hair too early—momentarily leaving the engine between “muscle” and “max flow” modes. It’s a minor quirk, but one that tuners and enthusiasts sometimes address with updated calibrations or aftermarket intake manifolds.

If you find your torque delivery feeling a tad soggy in the midrange, chances are you’re bumping into this very phenomenon. A tweak to the intake runner switch point—via custom tuning—can help flatten out that dip and keep the power flowing smoothly, whether you’re launching off the line or surging onto the highway.

Multi Displacement System

Featuring a cylinder deactivation system called MDS (multi displacement system). The engine has the ability to shut off fuel in the passenger bank of the engine when power is not needed.

This equipment was part of the initial design of the Hemi engine, not an afterthought, so it fully integrates into the engine design. This improved reliability by reducing complexity and lowered the manufacturing cost.

How it works is a hydrualic lifter activates, which cuts off the valve lifters so that there is no loss of energy by pumping air through those cylinders and compressing it.

The engine can complete this transition in less than .04 seconds, and unless you have super human senses, you will never know it is there.

Currently the 6.4L Hemi is only available in RAM HD trucks. Which paired to either the six-speed 68RFE automatic transmission or the six-speed Aisin-Seiki AS69RC medium-duty truck transmission.

FREQUENTLY ASKED QUESTIONS

What are the known issues, if any, with the 6.4 liter truck engine as of the latest information available?

Upon reviewing the latest available information, it appears that no significant issues have been identified with the 6.4 liter truck engine. This suggests a robust performance and reliability record to date.

Key Takeaways:

Current Status: No widespread or critical problems reported.
User Feedback: Generally positive reviews, focusing on reliability and power.
Performance: Often praised for its strong output and efficiency in various conditions.

For potential buyers and current owners, this is encouraging news. It underscores the engine’s solid build quality and performance, providing peace of mind for those considering its purchase or continued use. Always consult the latest updates from mechanics and user reviews to stay informed.

Discrepancies and Clarifications on 6.4L Hemi Camshaft Specs

While the 6.4L Hemi is celebrated for its robust design and performance, there’s been some healthy debate among enthusiasts regarding camshaft duration and lift figures—especially when measured at 0.050″ lobe lift. Several attentive readers have pointed out that some published duration specs have, in the past, been inconsistent or incorrect.

After cross-checking multiple reputable sources, the commonly accepted specs for the non-MDS 6.4L Hemi camshaft (Mopar PN#: 5037379BC) are as follows:

Lobe Separation Angle (LSA): 121°
Intake Valve Lift: 0.574″
Exhaust Valve Lift: 0.541″
Intake Duration @ 0.050″: 215°
Exhaust Duration @ 0.050″: 221°

For reference, some published figures have cited durations such as 286°/288° at 0.006″ lift, but those should not be confused with the 0.050″ specs typically used for comparison in aftermarket camshafts and tuning conversations.

A Closer Look at Measurement Methods and Enthusiast Corrections

It’s worth noting that discrepancies often arise from differences in how camshaft specs are measured and reported. Duration measured at 0.006″ lobe lift will naturally yield a much higher number than duration at 0.050″, a detail that can trip up even seasoned gearheads if they’re not careful. If you see published specs that seem wildly out of range, check the measurement point—industry standards like 0.050″ lobe lift (as used by Comp Cams and Crane Cams) are the go-to for reliable comparison.

This kind of confusion isn’t limited to cam specs. For example, debates have popped up over connecting rod big end bore measurements and corresponding crank rod journal sizes, with sharp-eyed readers chiming in to clarify that a con rod BE bore of 2.125″ typically indicates a crank rod journal of 2.000″, not 2.126″—a good reminder to double-check factory documentation or trusted technical manuals.

Staying Accurate with Community Input

Thanks to a watchful enthusiast community, data inconsistencies get flagged and corrected often. As with any specialty engine info, it’s a good practice to confirm numbers with the latest factory service publications or trusted aftermarket sources before planning any performance modifications. The ongoing conversation around specs—whether it’s camshaft timing or crank dimensions—helps keep the information accurate for everyone, from DIYers to seasoned builders.

When evaluating cam data, always ensure you’re comparing measurements at the same lift point (e.g., 0.050″ lobe lift) for apples-to-apples accuracy. Reputable aftermarket cam manufacturers also post their specs by this industry standard if you’re cross-referencing or considering upgrades.

When evaluating cam data, always ensure you’re comparing measurements at the same lift point (e.g., 0.050″ lobe lift) for apples-to-apples accuracy. Reputable aftermarket cam manufacturers like Comp Cams and Crane Cams also post their specs by this industry standard if you’re cross-referencing or considering upgrades.

What are the horsepower and torque specifications for the G2 5.7, 6.4 (SRT), and 6.4 Truck engines?

Engine Specifications

When comparing the horsepower and torque of various engines, it’s essential to consider each engine type’s specific attributes. Let’s take a closer look at the G2 5.7, 6.4 (SRT), and 6.4 Truck engines:

G2 5.7 Engine:

Horsepower: 390
Torque: 407

6.4 (SRT) Engine:

Horsepower: Ranges between 470 and 485
Torque: Between 470 and 475

6.4 Truck Engine:

Horsepower: 410
Torque: 429

These specifications highlight the performance differences among each engine type, catering to various needs and preferences. Whether you prioritize sheer power or balanced torque, understanding these figures is vital for making an informed choice.

Dyno Performance Figures for 2019+ 6.4L Truck Engines

If you’re evaluating gearing setups for towing and want to know how the 2019 and newer 6.4L Hemi truck engines perform on the dyno, here’s what you can expect:

On a chassis dynamometer—using commonly accepted correction factors—stock 6.4L truck Hemis (as found in Ram 2500/3500 models) typically put down:

Rear-Wheel Horsepower (RWHP): 325–345 hp
Rear-Wheel Torque: 375–395 lb-ft

Keep in mind, these numbers show what actually reaches the wheels, factoring in drivetrain losses—about 15–20% lower than the engine’s rated (crank) specs due to the heavy-duty automatic transmissions and 4WD systems. Variations exist depending on altitude, dyno type (Dynojet, Mustang, etc.), and fuel quality.

Towing Considerations:
For towing, torque is the real star. The 6.4L Hemi’s broad torque plateau—peaking between roughly 4,000 and 4,400 rpm—means you’ll have plenty of grunt within practical highway speeds and typical towing rpm ranges. Many owners find staying in the 3.73–4.10 axle ratio range offers a great compromise between towing performance and fuel efficiency. Careful attention to actual rear-wheel torque (not just the engine spec) can help fine-tune your gearing for your trailer and driving terrain.

For the latest dyno sheets and towing feedback, it’s always smart to check enthusiast forums or reach out to shops that specialize in heavy-duty Ram trucks—they frequently post real-world pull numbers and setups for a variety of towing applications.

What are the key specifications of the 2014 6.4 truck engine compared to the 5.7 truck engine?

Key Specifications of the 2014 6.4 Truck Engine vs. The 5.7 Truck Engine

When comparing the 2014 models of the 6.4 truck engine and the 5.7 truck engine, several key specifications highlight their differences:

Compression Ratio

5.7 Truck Engine: The compression ratio stands at 10.5:1.
6.4 Truck Engine: It has a slightly lower compression ratio at 10.0:1.

Maximum Revolutions Per Minute (RPM)

5.7 Truck Engine: Both engines share a maximum rev limit of 5,800 rpm.
6.4 Truck Engine: Also peaks at 5,800 rpm, but when paired with an Aisin transmission, it is limited to 4,660 rpm.

Oil Capacity

Both the 5.7 and 6.4 truck engines maintain an oil capacity of 7.0 quarts. For metric enthusiasts, the 6.4 engine additionally lists this as 6.62 liters.

Coolant Capacity

5.7 Truck Engine: This engine requires 18 quarts of coolant.
6.4 Truck Engine: The capacity is slightly reduced to 15.75 quarts, equivalent to 15 liters.

These specifications provide a clear comparison, showcasing where each engine stands concerning key performance and maintenance factors.

How does the 6.4 liter truck engine differ from the 6.4 liter SRT Hemis in terms of power and torque?

When examining the differences between the 6.4-liter truck engine and the 6.4-liter SRT Hemis, power and torque are key areas of contrast.

Power Differences

6.4-liter SRT Hemis: Deliver a robust 470-485 horsepower, designed for high-performance vehicles.
6.4-liter Truck Engine: Offers 410 horsepower, tailored specifically for heavy-duty trucks, focusing more on durability and load-bearing capacity than raw power.

Torque Comparison

6.4-liter SRT Hemis: Provides 470-475 lb-ft of torque, aimed at delivering rapid acceleration and enhanced performance.
6.4-liter Truck Engine: Produces 429 lb-ft of torque, optimized for a broad torque curve suitable for carrying heavy loads. It’s limited to 410 lb-ft when paired with a manual transmission, emphasizing steady power delivery over peak performance.

In summary, the truck engine is engineered for longevity and efficiency under demanding conditions, sacrificing some horsepower and torque in exchange for greater reliability and economy when handling heavy loads.

What is the 6.4 liter “truck Hemi” V8 engine and when was it launched?

Starting in 2014, Chrysler engineers debuted the new 6.4L Hemi engine, code named Apache. The 6.4L Apache displaces 392 cu-in, and as a medium-duty commercial truck option, falls in line with the 6.7L Cummins medium-duty rating, as well.

This engine was specially crafted for heavy-duty applications, particularly in Ram pickups and chassis cabs. Although it shares the same displacement, the 6.4L truck Hemi is distinct from the 6.4L SRT Hemis found in non-SRT vehicles. The truck version focuses on durability and torque to handle heavy loads, setting it apart from the sportier SRT variants that deliver 470-485 hp and 470-475 lb-ft of torque.

By creating a powerplant tailored for tough tasks, Chrysler ensured that the 6.4L Apache meets the demanding needs of commercial and heavy-duty users while maintaining performance and reliability.

Is the 6.4L HEMI engine suitable for modifications and boosts in power?

When considering modifications for increased power, the 6.4L HEMI engine may present some challenges. Here’s why:

Bottom End Limitations: The design of the stock bottom end isn’t optimized for handling significant boosts. This can limit the engine’s capability to sustain higher horsepower levels without risking damage.
Piston Composition: Unlike engines equipped with forged pistons designed to endure added stress, the 6.4L HEMI’s pistons have limitations. There isn’t ample material between the ring lands and the top of the piston, which can be a weak point under high pressure.
Exhaust Manifold Concerns: The exhaust manifold is another area of potential trouble. Under the stress of increased heat from enhanced power efforts, the manifold might twist. This could lead to the breaking of fastening studs, impairing the engine’s efficiency and reliability.
Comparison with Other Engine Series: Unlike GM’s LS series, which is known for its resilience to modifications, the 6.4L HEMI requires more cautious handling when considering boosts.

Overall, while the 6.4L HEMI engine can be modified to some extent, it may not be the ideal choice for significant power increases without substantial upgrades.

Tips and Resources for Sourcing Aftermarket Headers for Gen. III Hemi Swaps

Swapping a Gen. III Hemi into an older vehicle is a rewarding project, but selecting the right aftermarket headers can make or break your build. Here’s how to simplify the process:

1. Start with Fitment and Style

Shorty headers are a popular choice for engine swaps, especially when dealing with tight engine bays in classic cars. Their compact design often avoids common clearance issues.
Long-tube headers can provide increased performance but may require more extensive modifications to the exhaust system or chassis.

2. Explore Swap-Specific Solutions

Some manufacturers, like Hooker, Hedman, and TTI, produce headers specifically designed for popular Hemi swap platforms. These can drastically reduce installation headaches.

3. Consult Swap Guides and Project Articles

Research build threads and tech articles for your specific vehicle or a similar platform. Many enthusiasts document what worked (or didn’t) during their Hemi swaps—including part numbers, fitment quirks, and alternatives.

4. Consider the Exhaust System Layout

Think beyond just the header: ensure compatibility with your exhaust routing, steering components, and crossmembers. Sometimes, modifying the exhaust from the headers back can be simpler than adapting headers themselves.

5. Don’t Overlook Expert Advice

Reputable parts suppliers like Summit Racing, Jegs, and Speedway Motors offer tech support; their staff can walk you through fitment details for your application and point out issues to watch for.

6. Retain Essential Components

Integrating the Gen. III Hemi with its factory wiring harness and compatible transmission controller typically simplifies the swap. This can affect header selection, as shift linkage or wiring positions may impact clearance.

By leveraging these resources and planning ahead, your header selection process can be much smoother—making your classic Hemi swap as hassle-free as possible.

How reliable is the 6.4L HEMI engine over time?

Assessing the Long-Term Reliability of the 6.4L HEMI Engine

When considering the long-term reliability of the 6.4L HEMI engine, enthusiasts and everyday drivers will be pleased to discover its reputation for durability. This V8 engine is celebrated for offering robust power and torque while maintaining a strong track record over time.

Key Factors of Reliability

Proven Performance: Known for its impressive performance, the 6.4L HEMI delivers high power suitable for various driving needs, from daily commutes to more demanding terrains.
Minimal Issues Reported: To date, there have been no significant widespread issues impacting this engine when used under normal driving conditions. Its reliability is similar to its sibling, the 5.7L version.
‘MDS Ticking’: One characteristic sound associated with this engine is the mild ‘ticking’ due to its Multi-Displacement System (MDS). It is not detrimental to the engine’s performance or lifespan.

Maintenance Essentials

Oil Specifications: The use of 0W-40 synthetic oil is crucial for optimal performance, as recommended by engine manufacturers.
Oil Change Regularity: Keeping the oil clean and changed on schedule is vital to support the engine’s MDS system and overall health.

Warranty Coverage

This engine typically comes with a five-year or 100,000-mile factory warranty, adding a layer of assurance for long-term operation. This coverage underscores confidence in its durability.

Conclusion

Overall, the 6.4L HEMI engine is a reliable choice for those seeking consistent power and performance. With proper maintenance and adherence to oil specifications, it delivers durability that stands the test of time.

How does the 6.4L HEMI’s design and architecture compare to the 5.7L HEMI?

Core Construction and Block Design

Both the 6.4L and 5.7L HEMI engines share a foundational 90-degree, cast-iron cylinder block with a sturdy deep-skirt design. However, the similarities largely end there. They differ in bore diameter and stroke size, which sets the 6.4L apart with more advanced engineering features.

The 6.4L hosts a forged steel crankshaft, offering enhanced strength and durability compared to its 5.7L counterpart. In both engines, the main bearing caps are secured with cross-bolts, but the 6.4L adds sophistication with piston cooling jets. These oil jets effectively manage heat by spraying oil on the pistons, a feature absent in the 5.7L.

Cooling and Piston Innovations

The advanced cooling system in the 6.4L uses an oil-to-water cooler to maintain optimal performance even under demanding conditions. It also boasts revised connecting rods made from high-strength powder metal and new larger flat-top pistons, distinguishing it from the 5.7L’s simpler configuration.

Head Design and Airflow

The 6.4L cylinders adopt a two-valve, two-spark plug design per cylinder, similar to the late iterations of the 5.7L HEMI. Their combustion chambers are oval-shaped and semi-hemispherical. The 6.4L engine’s cylinder heads improve airflow with an 11% boost in intake and a 13% increase in exhaust port flow, surpassing the air-handling capabilities of the 5.7L.

Intake Systems

While high-speed applications of the 6.4L utilize a plastic intake manifold with shorter runners, engineered for vehicles demanding quick acceleration, the truck variant uses an active dual-runner-length intake manifold. This design optimizes both low- and mid-range power, delivering a broader performance spectrum without sacrificing top-end power—a feat the 5.7L struggles to match.

Throttle and Timing Mechanisms

Both the 6.4L and 5.7L engines employ drive-by-wire throttle bodies, ensuring responsive engine control. However, the 6.4L stands out with a cam-in-block variable valve timing (VVT) system, using hydraulic cam phasing for precise valve operation. This technology contributes to a refined driving experience, setting a higher standard compared to the more traditional timing methods in the 5.7L.

Valvetrain Enhancements

The 6.4L engine’s valvetrain includes hydraulic roller lifters and sodium-filled exhaust valves, specialized for managing heat and improving longevity. These features underscore a modern approach to engine design, offering significant advancements over the 5.7L.

To further illustrate the technical sophistication, the 6.4L valvetrain system features:

Hydraulic roller lifters seated in a plastic retainer for reduced friction and consistent performance.
Lifter body diameter: 0.842″, contributing to stability and efficiency at higher RPMs.
Shaft-mounted rocker arms with a die-cast, roller-fulcrum design that improves durability and valve actuation precision.
Rocker ratio: 1.60:1 on the intake side and 1.66:1 on the exhaust, aiding in optimal valve lift and airflow.
Beehive-style valve springs for enhanced valve control and reduced weight, allowing for smoother operation at high speeds.
Valve angle: 18° intake and 16.5° exhaust, promoting mixture flow and combustion efficiency.
Spring-loaded timing chain tensioner for reliable chain control and quieter operation.

Together, these enhancements ensure the 6.4L Hemi’s valvetrain is engineered for both robust performance and long-term reliability, making it a standout in modern V8 design.

In summary, while the 6.4L HEMI shares structural heritage with the 5.7L, it surpasses it with sophisticated innovations in cooling, airflow management, and valve timing, making it a more high-performance and resilient engine.

Read More: 2UZ-FE 4.7L : Toyota’s Heavyweight V8

What are the engine specifications for the 6.4L HEMI, such as bore, stroke, and displacement?

Engine Specifications:

Bore and Stroke: The engine features a bore of 103.9 mm (4.09 in) and a stroke of 94.6 mm (3.72 in), contributing to its 6,407 cc (392 cu in) displacement.
Materials: The cylinder block is constructed from durable cast iron, while the cylinder head utilizes lightweight aluminum.
Configuration: This V8 engine operates with two valves per cylinder, employing an OHV valvetrain layout for efficient performance.
Fuel System: It runs on gasoline, with a sequential multi-port injection system ensuring optimal fuel delivery.

Performance:

Power Output: Depending on the application, the 6.4L Hemi generates between 366-485 horsepower (273-362 kW).
Torque: It delivers 429-475 ft-lb (582-644 Nm) of torque, providing robust performance across a range of conditions.
Compression Ratio: The engine’s compression ratio varies, with 10.9:1 for the SRT models and 10.0:1 for Ram trucks.

Technical Details:

Engine Weight: The dry weight stands at approximately 500 lbs (227 kg).
Firing Order: The engine’s firing order is 1-8-4-3-6-5-7-2, ensuring balanced operation.
Oil Specifications: It requires SAE 0W-40 engine oil, with a capacity of 6.7 liters (7.0 qt) including the oil filter. The recommended oil change interval is every 6,000 miles (10,000 km) or six months.

Applications:

This versatile engine powers a range of vehicles, including the Ram 2500/3500/4500/5500 and Cab Chassis models, as well as high-performance versions of the Dodge Challenger, Charger, Chrysler 300, Jeep Grand Cherokee, and Dodge Durango.

By blending raw power with refined engineering, the 6.4L Hemi Apache stands out as a formidable choice for both commercial and high-performance applications.

Fully Dressed Engine Weight

When considering a complete, ready-to-install 6.4L HEMI engine—including all major accessories and components—the total “full dress” weight comes in at approximately 582 lbs. This figure accounts for essentials like the intake manifold, exhaust manifolds, starter, alternator, and other attached hardware, reflecting the engine’s robust commercial-grade build.

What types of vehicles have the 6.4L HEMI engine been used in?

Currently, the 6.4L Hemi is only available in RAM HD trucks paired to either the six-speed 68RFE automatic transmission or the six-speed Aisin-Seiki AS69RC medium-duty truck transmission. However, this powerful engine has found its place in a diverse array of vehicles, showcasing its versatility and performance capabilities.

Vehicles Featuring the 6.4L HEMI Engine

RAM Trucks: Beyond the HD line, the 6.4L HEMI engine powers models like the RAM 2500, 3500, 4500, and 5500, including Cab Chassis configurations. This makes it a popular choice for heavy-duty applications requiring robust power.
Dodge Performance Cars:
- Challenger: Offered in high-performance trims like the SRT8, R/T Scat Pack, and SRT, the Challenger utilizes the 6.4L HEMI for exhilarating performance.
- Charger: Similarly, the Charger SRT8, R/T Scat Pack, and SRT models benefit from the engine’s robust power output.
Chrysler and Jeep:
- Chrysler 300: The SRT8 and SRT versions of the Chrysler 300 deliver premium performance enhanced by the 6.4L HEMI.
- Jeep Grand Cherokee: In the SRT8 and SRT trims, this engine provides the Grand Cherokee with a significant performance boost.
Dodge Durango: The Durango’s SRT8 and SRT models also feature the 6.4L HEMI, combining SUV practicality with impressive power.

This engine’s application across such a wide range of vehicles highlights its adaptability and appeal to both performance enthusiasts and those needing reliable power for heavy-duty tasks.

Model-Year Performance Overview: 6.4L HEMI Apache Applications

When looking at how the Gen. III 6.4L HEMI has been implemented across various vehicles, it’s clear that each model and year brings its own performance flair. Here’s a snapshot of key applications, highlighting horsepower and torque figures where they matter most.

Dodge Challenger SRT8 (2011–2014):

Power: 460 horsepower at 6,000 RPM
Torque: 470 ft-lbs at 4,200 RPM

Dodge Challenger SRT8 (2015):

Upgraded to 485 horsepower at 6,100 RPM
Torque: Peaks at 475 ft-lbs at 4,700 RPM

Jeep Grand Cherokee SRT & Dodge Durango SRT (2015):

Power: 475 horsepower at 6,000 RPM
Torque: 470 ft-lbs at 4,300 RPM

RAM 2500/3500 (2014+):

Power: Ranges from 366 to 410 horsepower at 5,600 RPM (model and configuration dependent)
Torque: Robust 429 ft-lbs at 4,000 RPM

These figures underscore the engine’s capability to adapt for both hard-working trucks and adrenaline-driven performance cars. The 6.4L HEMI continues to set the standard, offering substantial power and torque tailored to each vehicle’s role and personality.

Model Years and Applications of the 2011+ Gen. III 6.4L Hemi Apache Engine

The Gen. III 6.4-liter Hemi Apache engine, since its debut in 2011, has powered an impressive lineup of performance vehicles and heavy-duty trucks. Here’s a closer look at the primary models and years where this powerhouse has made its mark:

Dodge Challenger SRT8 (2011–2014)
Throughout these years, the Challenger SRT8 championed the 6.4L Hemi, delivering robust horsepower and torque—ideal for enthusiasts seeking thrilling acceleration.
Dodge Challenger SRT/Scat Pack (2015+)
Updates in 2015 brought even more performance to the Challenger lineup, with the SRT and Scat Pack trims making use of the enhanced output from the Apache engine.
Dodge Charger SRT and R/T Scat Pack (2015+)
The Charger also benefitted from the 6.4L Apache, with spirited driving dynamics and substantial torque numbers specifically in the SRT and Scat Pack models.
Jeep Grand Cherokee SRT (2015+)
In the world of performance SUVs, the Grand Cherokee SRT harnessed the 6.4L Hemi to offer muscle car thrills in a practical package.
Dodge Durango SRT (2018+)
Bringing muscle-inspired performance to a three-row SUV, the Durango SRT utilizes the 6.4L for both towing power and speedy sprints.
Ram 2500 and 3500 Heavy Duty Trucks (2014+)
The commercial-grade strength and durability of the 6.4L Apache have served well in Ram‘s 2500 and 3500 trucks, especially suited for those needing reliable muscle for hauling and work tasks.

Thanks to its blend of brute force and versatility, the 2011+ Gen. III 6.4L Hemi Apache continues to carve out a reputation in both high-performance street vehicles and the demanding world of heavy-duty trucks.

How does the 6.4 liter truck Hemi engine compare to other modern and classic Hemi engines?

Comparing the 6.4 Liter Truck Hemi to Other Hemi Engines

The 6.4-liter truck Hemi V8, introduced in the 2014 model year, offers a balance of durability, power, and efficiency, specifically designed for heavy-duty applications in Ram pickups and chassis cabs. Here’s how it stacks up against other modern and classic Hemi engines.

Modern Hemi Engines

7 Liter Hemi: Known for its versatility across a range of applications, the 5.7 Hemi offers commendable power with 390 horsepower and 407 lb-ft of torque. It’s a popular choice for light-duty trucks.
4 Liter SRT Hemi: This performance-oriented variant delivers between 470 and 485 horsepower, alongside 470 to 475 lb-ft of torque, making it suitable for high-performance vehicles. Unlike the 6.4 truck engine, it prioritizes top-end power.
Supercharged ‘Hellcat’: Setting a high benchmark, the Hellcat variant offers extreme horsepower well beyond the standard Hemis, tailored for performance enthusiasts looking for maximum thrill.

6.4 Liter Truck Hemi Specifics

The 6.4 truck Hemi diverges from its SRT counterpart by focusing on longevity and efficiency under heavy loads. Producing 410 horsepower and 429 lb-ft of torque, it aligns power output with practical usability for trucks, adapting features like an active dual-runner-length intake manifold and cylinder deactivation for efficiency.

It utilizes robust materials and advanced technologies, such as sodium-filled exhaust valves, to withstand rugged use. This engine built for resilience also involves innovations like the integrated PCV system, enhancing performance and reducing oil consumption.

Special Feature: In certain chassis cabs with a gross vehicle weight rating above 10,000 pounds, the engine is rated at 367 horsepower, illustrating its adaptability to different heavy-duty requirements.

Classic Hemi Engines

426 Hemi (“Elephant Engine”): Favored for its legendary status and high performance in muscle cars of the past, this engine remains iconic for enthusiasts and collectors due to its historical significance and raw power.
392 Crate Hemi: Known for being a versatile upgrade option for classic car restorations, it captures the essence of the original Hemis while offering improved performance and reliability.

In summary, the 6.4-liter truck Hemi integrates both modern advancements and traditional engineering prowess, standing out with its targeted focus on durability and efficiency tailored for heavy-duty applications while offering a unique comparison to both modern and classic Hemi engines.

What are the known issues or reliability concerns associated with the 6.4 liter truck Hemi engine?

Known Issues and Reliability Concerns for the 6.4 Liter Truck Hemi Engine

1. Camshaft and Lifter Failure

One of the primary concerns with the 6.4-liter Hemi engine is the potential for camshaft and lifter failure. This issue often leads to noticeable ticking sounds, decreased performance, and can result in expensive repairs if not addressed promptly.

2. Exhaust Manifold Bolt Breakage

Drivers often report broken exhaust manifold bolts, which can cause exhaust leaks. Over time, this issue can lead to decreased engine efficiency and increased emissions, requiring attention to prevent further complications.

3. Transmission Challenges

While not directly part of the engine, the transmission of vehicles equipped with the 6.4-liter Hemi is sometimes noted for rough shifting. This can affect overall driving experience and longevity if not serviced regularly.

4. Cooling System Concerns

Some users have highlighted cooling system inefficiencies. The engine may run hotter than expected, especially under heavy loads, necessitating vigilance and regular maintenance checks.

5. Fuel Economy

Considering its power, the 6.4-liter Hemi is not renowned for fuel efficiency. Owners seeking improved mileage may find this aspect a challenge without sacrificing performance.

Maintenance Tips

Regular Oil Changes: Keeping up with oil changes can help mitigate wear and tear, especially concerning cam and lifter issues.
Routine Inspections: Regular checks of the exhaust system and cooling components can prevent small problems from becoming major ones.
Proper Load Management: Avoiding excessive towing beyond the engine’s capacity can prevent overheating and undue stress.

By addressing these concerns proactively, owners can enhance the reliability and longevity of the 6.4-liter Hemiengine.

How does the ignition system in the 6.4 liter truck Hemi engine work to reduce emissions?

A unique dual-spark system on the engine gives two spark plugs per cylinder, with the coil plug firing the plug it resides over and a wire that runs across the engine to the opposite bank to fire that plug. The extra plug fires during the power stroke to more fully burn the fuel in the cylinder, which provides more power in the down stroke and also numbers the amount of catalyst plates needed in the exhaust system.

This system employs eight coils to fire 16 spark plugs, enhancing combustion efficiency. By igniting the extra plug during the power stroke, the fuel is burned more completely, which not only increases power output but also optimizes the emissions process.

Additionally, this approach allows the primary spark plug to fire closer to top dead center. This precise timing contributes to increased torque and significantly reduces NOx emissions, cutting down on pollutants like ozone. As a result, the ignition system plays a pivotal role in minimizing environmental impact while maximizing engine performance.

What technologies are used in the 6.4 liter truck Hemi engine to improve fuel efficiency?

Featuring a cylinder deactivation system called MDS (multi displacement system), the engine has the ability to shut off fuel in the passenger bank of the engine when power is not needed. This equipment was part of the initial design of the Hemi engine, not an afterthought, so it fully integrates into the engine design.

This improved reliability by reducing complexity and lowered the manufacturing cost. How it works is a hydraulic lifter activates, which cuts off the valve lifters so that there is no loss of energy by pumping air through those cylinders and compressing it. The engine can complete this transition in less than 0.04 seconds, and unless you have superhuman senses, you will never know it is there.

Additionally, the engine employs a cooled EGR (Exhaust Gas Recirculation) system to further enhance fuel efficiency by reducing the engine’s temperature and improving combustion efficiency. This combination of technologies ensures that the engine operates with lower emissions and greater fuel economy.

The engine’s design is robust, featuring a deep-skirt configuration with a cast iron block and a forged steel crank. The main bearing caps are cross-bolted, echoing the design principles found in other high-performance engines. The use of 356 aluminum for the heads contributes to a lighter engine overall, aiding in efficiency without sacrificing durability.

By integrating these technologies from the ground up, the engine achieves a balance of power and efficiency, offering a seamless driving experience that prioritizes both performance and fuel savings.

What design features contribute to the 6.4 liter truck Hemi engine’s durability and efficiency?

Durability and Efficiency Features

Deep-Skirt Design: The engine’s deep-skirt design and cast iron block provide a solid foundation, enhancing structural integrity and reducing wear and tear over time.
Forged Steel Crank & Cross-Bolted Main Bearing Caps: These features further bolster the engine’s toughness, ensuring it can handle heavy-duty usage without compromising performance.
Advanced Cooling System: With a high-volume oil cooler and computational fluid dynamics, the engine maintains optimal temperatures, essential for both durability and efficiency.
Variable Valve Timing: The hydraulic cam phasing system, controlled by a computer, offers precise valve timing adjustments, enhancing fuel efficiency and performance.
Cylinder Deactivation: Known as the Multi Displacement System (MDS), this feature turns off the fuel in four cylinders when not needed, improving fuel economy without sacrificing power. Transitions occur in under 0.04 seconds, showcasing seamless integration and reliability.

These thoughtfully engineered features, from robust materials to innovative systems, ensure the 6.4L Apache not only performs exceptionally but also stands the test of time in demanding conditions.

What materials and design choices are used in the construction of the 6.4 liter truck Hemi engine?

“Receiving upgrades in the form of tough alloy exhaust valve seats, sodium-filled exhaust valves, aircraft-grade stainless steel gaskets and fasteners, and a high-efficiency and high-flow oil cooling system with piston jets and an oil cooler designed with the aid of computational fluid dynamics. All forged internals, with a cast iron block, cross-bolted main-bearing caps, and 356 aluminum—and the list keeps going and going.

The engine’s design incorporates a deep-skirt block, ensuring structural integrity with a cast iron construction and a forged steel crank. This robust foundation is complemented by heads crafted from 356 aluminum, providing a balance of strength and weight reduction.

Key Construction Details and Specifications

Block Material: Cast iron, offering long-term durability and torsional strength.
Displacement: 6.4 liters (391 cubic inches), combining generous bore and stroke for both torque and horsepower.
Bore Diameter: 4.090″, with a stroke of 3.72″, maximizing cylinder volume while maintaining reliability.
Deck Height: 9.25″, contributing to the engine’s stoutness and compatibility with high-performance internals.
Main Cap Design: Two-bolt main caps with additional lateral cross-bolts, enhancing crankshaft stability under load.
Thrust Bearing Location: Positioned at number 3 for optimal load distribution.
Bore Spacing: 4.46″, echoing classic V8 proportions yet designed for modern durability.
Cam-to-Crank Centerline: 7.44″, engineered for precise valvetrain geometry.
Piston Oil Squirters: Yes, with targeted cooling jets to keep pistons at optimal temperatures under hard use.
Bellhousing Pattern: Utilizes a familiar small block bolt pattern (with a minor update—top center bolt omitted) for compatibility across a range of applications.

From the material choices—like robust iron for the block and lightweight yet strong 356 aluminum for the heads—to the inclusion of features such as sodium-filled exhaust valves, forged steel crank, and advanced oil cooling passages, every detail is aimed at maximizing both longevity and efficiency. All these elements combine to create an engine that’s as tough as it is refined, perfectly suited for the rigorous demands of heavy-duty work or spirited driving alike.

Efficiency is at the forefront with the inclusion of cooled Exhaust Gas Recirculation (EGR) and a cylinder deactivation system, known as the Multi Displacement System (MDS). This system elegantly deactivates fuel in four cylinders when full power isn’t necessary, transitioning seamlessly in under 0.04 seconds, enhancing fuel efficiency without compromising performance.

A hydraulic cam phasing system governs the variable valve timing, utilizing computer control to optimize engine responsiveness and power delivery. The integration of oil passages within the camshaft to drive the cam phaser sprocket exemplifies the attention to detail in its engineering.

Every aspect of this engine is tailored for maximum reliability and performance, showcasing a blend of cutting-edge technology and robust materials that ensure longevity and efficiency.”

What specific failure modes (like exhaust manifold twisting and stud failure) are seen in the 6.4L HEMI under heavy modification?

Under substantial power increases, the 6.4L HEMI’s pistons can be a weak link due to their non-forged construction and limited material between the ring lands and piston top. Additionally, the exhaust manifold is prone to distortion from heat, which can result in broken mounting studs, potentially compromising engine reliability.

How does the 6.4L HEMI compare and contrast with the 6.7L Cummins diesel for heavy-duty truck use?

The 6.4 HEMI is positioned as a gasoline-powered alternative to the 6.7L Cummins turbocharged diesel. While both are designed for demanding work in Ram trucks, the HEMI provides a naturally aspirated V8 option with robust performance for those who prefer gas engines over diesel, particularly in tasks requiring consistent torque and durability.