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

We are living the last golden hours of the 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 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. 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.

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.

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

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 paired to either the six-speed 68RFE automatic transmission or the six-speed Aisin-Seiki AS69RC medium-duty truck transmission.

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FREQUENTLY ASKED QUESTIONS

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

Known Issues with the 6.4 Liter Truck Engine

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.

 

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.

 

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 efficiency features are included in the 6.4 liter truck engine design?

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.

In addition to the MDS, the engine design includes a cooled Exhaust Gas Recirculation (EGR) system, enhancing efficiency by reducing emissions and improving fuel economy. The engine features a robust deep-skirt design with a cast iron block and forged steel crank, ensuring durability and longevity. Cross-bolted main bearing caps and 356 aluminum heads contribute to its structural integrity and performance.

These design choices reflect a commitment to efficiency and reliability, with fewer parts leading to maximum reliability and lower costs. The seamlessly integrated MDS system and other advanced features combine to create an engine that excels in both power and efficiency, setting a high standard for performance.

 

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:

1. 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.
2. 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.
3. 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.
4. 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.

 

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

1. Oil Specifications: The use of 0W-40 synthetic oil is crucial for optimal performance, as recommended by engine manufacturers.
2. 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?

Comparing the 6.4L HEMI with 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.

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.

 

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

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.

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.

 

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.

 

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 HemiEngine

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.

 

What was the initial transmission setup for the 6.4 liter truck Hemi engine upon launch?

Upon its release, the 6.4-liter truck Hemi engine was initially paired with the 66RFE automatic transmission. For those seeking alternatives, a six-speed Aisin transmission was also available as an option.

 

How does the 6.4 liter truck Hemi engine differ from the 6.4 liter SRT Hemis?

The 6.4-liter truck Hemi engine and the 6.4-liter SRT Hemis may share the same displacement, but they are designed for distinct purposes, resulting in notable differences.

Power and Torque:

• The 6.4-liter SRT Hemis, found in various performance-focused vehicles, deliver impressive power, ranging from 470 to 485 horsepower and torque between 470 to 475 lb-ft.
• In contrast, the truck Hemi engine, tailored for heavy-duty applications, offers a more modest power output. It’s designed to provide 367 horsepower at 4,600 rpm and 429 lb-ft of torque at 4,000 rpm in heavier vehicles. In lighter-duty vehicles, it ramps up to 410 horsepower.

Design and Fuel:

• Durability and fuel efficiency under hefty loads were paramount in the truck Hemi’s design. It achieves this balance by providing a broad torque curve, and it operates efficiently on 89 octane fuel.

Transmission Compatibility:

• This engine pairs exclusively with a six-speed automatic transmission. The standard pairing is with the 66RFE automatic transmission, though the six-speed Aisin is available as an option.

In summary, while both engines share a displacement of 6.4 liters, the truck Hemi is crafted for robustness and efficient performance under load, unlike the high-power, performance-tuned SRT Hemis.

 

What are the compression ratios and other technical specifications for the 6.4 liter truck Hemi engine?

An active dual-runner-length intake manifold boosts both low and high-end power by maximizing the natural supercharger effect of the manifold. Coupled with a 10.9:1 compression ratio, this big engine delivers an impressive 410 hp and 429 lb-ft of torque. Variable valve timing through a hydraulic cam phasing system ensures that the engine can run seamlessly on regular gasoline, even while achieving maximum output on mid-grade 89 octane fuel.

For those interested in a deeper dive into technical specifications, let’s break down the details of the 6.4-liter truck engine:

• Compression Ratio: 10.0:1
• Max Revs: 5,800 rpm, dropping to 4,660 with Aisin transmission
• Oil Capacity: 7.0 quarts (equivalent to 6.62 liters)
• Coolant Capacity: 15.75 quarts (15 liters)

These specifications highlight the robust design and efficiency of the engine, ensuring not only powerful performance but also reliability in various driving conditions. By combining advanced technology with these technical specs, the engine stands out as a formidable powerhouse in its category.

 

What are the horsepower and torque specifications for the 6.4 liter truck Hemi engine compared to other engines?

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.

To understand how this engine compares to others, consider the full spectrum of performance:

• G2 5.7 Engine
  • Horsepower: 390 hp
  • Torque: 407 lb-ft
• 4 (SRT)
  • Horsepower: 470-485 hp
  • Torque: 470-475 lb-ft
• 4 Truck Engine
  • Horsepower: 410 hp
  • Torque: 429 lb-ft
  • Note: Manual transmission is limited to 410 lb-ft torque.
• 4 Truck Engine (certain chassis cabs)
  • Horsepower: 367 hp at 4,600 rpm
  • Torque: 429 lb-ft
  • Note: Applies to chassis cabs over 10,000 lb GVWR.

This detailed comparison highlights not only the robust power delivered by the 6.4-liter truck Hemi engine but also illustrates its versatility across different applications. Whether you’re looking for raw horsepower or substantial torque, this engine stands out with its balanced performance and adaptability.

 

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?

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.

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.

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.”

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