Unleashing Power: The 6.4L HEMI V8 Engine Explained

Chrysler currently produces the largest OE gasoline V8 engine commercially available, and it stuffs it in a multitude of vehicles from Dodge Chargers to RAM trucks.

The 6.4L HEMI V8, known by the codename “Apache”, is a medium-duty 90-degree pushrod V8 with two large valves per cylinder, 16 spark plugs, 410 horsepower and 429ft-lbs of torque. Featuring all-forged internals, cross bolted main journals, a nodular cast-iron block and aluminum heads – Chrysler went all out on what would become one of the best V8s on the block in some time.

It is a gasoline V8 in a 3/4 ton truck though, right? So it has to be thirsty… or so you would think.

We are here to tell you that yes, absolutely – it is. But not as bad as you would think.

The vehicle of choice in this story is a 2017 RAM 2500 Power Wagon, which when stock had 285/70R17D Goodyear Wrangler Duratrac tires and a gear ratio of 4.11. Stock, the vehicle saw 12-13mpg returns in the city, and 16-17mpg on the highway.

In it’s current iteration, the Power Wagon is now rolling on 37×13.50R20E Falken Wildpeak MT’s and 20×9.5” Trail Ready Beadlock wheels, and returns roughly the same fuel economy numbers.

So yes, the Apache is thirsty – but its a thorn in your side you can live with.

FREQUENTLY ASKED QUESTIONS

How reliable is the 6.4L HEMI engine for long-term use?

The 6.4L HEMI engine is celebrated for its robust performance and reliability over the long haul. This V8 powerhouse is known for delivering impressive horsepower and torque, making it a favorite among enthusiasts who value both power and dependability.

Durability and Longevity

Owners report that this engine consistently performs well over extended periods, showcasing remarkable endurance under normal driving conditions. It’s designed with American pushrod technology, a testament to its sturdy construction, contributing to its long lifespan. With proper maintenance, the 6.4L HEMI can efficiently cover hundreds of thousands of miles.

Warranty and Assurance

To top it off, the engine typically comes with a substantial factory warranty, often around five years or 100,000 miles, providing additional peace of mind to users. This warranty is a strong indicator of the manufacturer’s confidence in the engine’s longevity and reliability.

Summary

Overall, the 6.4L HEMI engine stands out as a reliable option for those seeking a V8 that’s built to last. Its track record of durability, combined with robust warranty support, makes it a solid choice for long-term use.

What maintenance is recommended for the 6.4L HEMI engine to ensure its longevity?

Recommended Maintenance for the 6.4L HEMI Engine

To ensure the longevity of your 6.4L HEMI engine, it’s crucial to adhere to specific maintenance practices:

• Oil Selection and Change: This engine relies on high-quality, thin 0W-40 oil. Always use the recommended oil to ensure optimal performance. Regular oil changes are essential, so stick to the manufacturer’s schedule to keep the engine running smoothly.
• Cylinder Deactivation System Care: The 6.4L HEMI features a Cylinder Deactivation System that benefits significantly from using clean oil. Fresh oil helps maintain efficient engine operation, particularly with this system.
• Routine Inspections and Services: Regularly check all fluid levels, and inspect components like spark plugs, air filters, and belts. Address any wear and tear promptly to prevent long-term damage.
• Keep It Clean: Ensure that the engine bay remains free from debris. This helps components function properly and reduces the risk of overheating.

By following these maintenance tips, you can enjoy the powerful performance of your 6.4L HEMI engine for years to come.

What are the common problems associated with the 6.4L HEMI engine?

Common Problems with the 6.4L HEMI Engine

The 6.4L HEMI engine is renowned for its power and reliability, but like any machine, it’s not without its quirks. Here’s a closer look at some common issues you might encounter:

• Hemi Ticking Sound: A familiar trait among HEMI engines, this subtle ticking noise is linked to the engine’s Multiple Displacement System (MDS). While the noise might be unsettling, it’s typically harmless. Proper maintenance, including regular oil changes using 0W-40 weight oil, is crucial.
• Cylinder Deactivation Sensitivity: The engine’s MDS system requires clean, specific oil to function optimally. Skipping oil changes or using the wrong oil can lead to performance issues.
• Exhaust Manifold Issues: The stock exhaust manifold is prone to distortion from high temperatures, potentially causing the manifold to warp and the studs to fail. This could lead to exhaust leaks and might require replacement parts.
• Engine Bottom End Limitations: Designed for durability rather than extreme power boosts, the stock engine’s bottom end can struggle under added stress. Non-forged pistons can limit the engine’s ability to handle significant power increases without risk of damage.

In Conclusion

The 6.4L HEMI is generally a robust engine, especially when used within its intended parameters. Regular maintenance and using recommended materials can help prevent many common issues, ensuring longevity and performance.

Why is the 6.4L HEMI engine not suitable for high levels of boost or power modifications?

Why the 6.4L HEMI Engine Isn’t Ideal for High Boost or Power Modifications

The 6.4L HEMI engine, while powerful in its stock form, presents some limitations when it comes to handling high levels of boost or significant power enhancements. Here’s why:

1. Piston Construction: The engine’s pistons are not forged, which is a key factor when considering modifications for higher power output. Forged pistons are typically more durable under increased pressure and heat, making them essential for high-boost applications. In the 6.4L HEMI, the pistons lack sufficient material between the ring lands and the top, making them vulnerable to damage under intense conditions.
2. Bottom-End Durability: The engine’s bottom end, which includes the crankshaft, connecting rods, and related components, isn’t designed to withstand the additional stress that comes with increased power. This foundational weakness means that the engine is more susceptible to failures if pushed beyond its intended performance limits.
3. Exhaust Manifold Concerns: Another challenge is the exhaust manifold. Under high heat and pressure, the manifold may warp. This distortion can lead to the failure of the fastening studs, potentially causing leaks or further mechanical issues.

Overall, while the 6.4L HEMI is a robust engine for standard applications, these structural components make it less ideal for heavy modifications aimed at significantly boosting power and performance.

How does the cylinder head design of the 6.4L HEMI engine contribute to its performance?

The 6.4L HEMI engine’s cylinder head design plays a crucial role in enhancing its performance. Mimicking the structure of late 5.7 HEMI heads, each cylinder head includes two valves and dual spark plugs per cylinder—totaling 16 spark plugs. This setup optimizes the combustion process, ensuring efficient power delivery.

Enhanced Airflow

Key to its design is the increased cross-sectional area of the head ports, facilitating better airflow. The intake ports boast an 11% improvement, while exhaust ports see a 13% enhancement. This superior flow design contributes significantly to the engine’s ability to produce higher power outputs and improved fuel efficiency.

Optimized Combustion Chambers

The semi-hemispherical, oval-shaped combustion chambers are another standout feature. This unique shape allows for more effective air and fuel mixing, leading to explosive combustion and, consequently, more power.

Intake Manifold Varieties

For different vehicle applications, the engine utilizes distinct intake manifold designs. A plastic intake manifold with shorter runners caters to high-speed performance, ideal for sporty cars. Meanwhile, the truck variant of this engine employs an active dual-runner-length intake manifold. This versatile manifold adjusts to provide optimal performance across low and mid-range speeds while still maintaining the necessary power for high-end performance.

In summary, the thoughtful design of the 6.4L HEMI’s cylinder heads significantly contributes to its robust performance by improving airflow, enhancing combustion, and adapting the intake manifold to suit diverse driving needs.

What are the differences between the SRT and truck versions of the 6.4L HEMI engine?

Differences Between the SRT and Truck Versions of the 6.4L HEMI Engine

The 6.4L HEMI engine is renowned for its power and versatility, but it comes in two distinct versions tailored for different types of vehicles: the SRT performance models and trucks.

SRT Version: Built for Speed

• Intake Manifold Design: The SRT variant features a plastic intake manifold with shorter runners. This design is optimized for high-speed performance, allowing the engine to breathe efficiently and deliver impressive horsepower, especially at higher RPMs.
• Performance Focus: Geared towards delivering high-end power, the SRT engine variant is perfect for muscle cars and performance-oriented vehicles, where maximum speed and acceleration are key.

Truck Version: Balanced for Versatility

• Active Dual-Runner Intake: The truck version of the 6.4L HEMI is designed with an active dual-runner-length intake manifold. This innovative feature caters to a broad range of engine speeds, enhancing performance in low to mid-range speeds without sacrificing the high-end power characteristics.
• Adaptability: Suited for larger vehicles, this engine offers a balanced approach, providing the necessary torque needed for towing and hauling while maintaining efficiency and power across various driving conditions.

In summary, the main differences lie in the intake manifold design and the intended performance application. The SRT version prioritizes top-speed capabilities, whereas the truck version focuses on versatility and adaptability across diverse driving scenarios.

How does the 6.4L HEMI engine compare to the 5.7L HEMI and the 6.7L ISB Cummins engines?

Comparing the 6.4L HEMI, 5.7L HEMI, and 6.7L ISB Cummins Engines

When deciding between the 6.4L HEMI, 5.7L HEMI, and 6.7L ISB Cummins engines, the choice largely depends on your specific needs, as each has unique advantages.

6.4L HEMI

The 6.4-liter HEMI V8 is a naturally aspirated engine offering impressive power and torque, designed with a focus on performance. It evolved from its 5.7L counterpart with enhancements that make it ideal for heavy-duty tasks. This engine is well-suited for applications that require both strength and reliability, such as hauling and towing. Its solid performance makes it a popular choice for those who need a robust gasoline engine in trucks.

5.7L HEMI

The smaller 5.7-liter HEMI is also a V8 engine known for its balance of power and fuel efficiency. It’s a versatile option for those who value performance but don’t necessarily require the extra power offered by the 6.4L version. While it doesn’t offer the same torque as the 6.4L, it provides sufficient capability for everyday use and moderate towing tasks, making it a practical choice for light-duty pickups and passenger vehicles.

6.7L ISB Cummins

On the other hand, the 6.7-liter ISB Cummins is a turbocharged diesel engine prized for its incredible torque output. This engine is particularly advantageous for heavy-duty towing and long-distance hauling, offering superior fuel efficiency compared to its gasoline counterparts. Its durability and towing capacity make it the engine of choice for serious commercial and industrial applications.

In summary, choose the 6.4L HEMI for a blend of power and versatility in gasoline form, the 5.7L HEMI for a more economical V8 option, or go with the 6.7L ISB Cummins if your needs demand maximum torque and efficiency in a diesel engine.

How does the Multi Displacement System (MDS) work in the 6.4L HEMI truck engine?

The Multi Displacement System (MDS) in the 6.4L HEMI truck engine enhances efficiency by utilizing an intelligent cylinder deactivation process. This system seamlessly integrates with the engine’s architecture and intelligently reduces the number of active cylinders when full power isn’t required.

Here’s a breakdown of how it works:

• Cylinder Deactivation: When cruising on highways or during light-load conditions, the MDS system deactivates four cylinders. This is achieved by cutting off the fuel supply and disabling the valve lifters for these cylinders.
• Reduction of Pumping Losses: By shutting down the valve lifters, the system minimizes unnecessary pumping losses, which enhances fuel efficiency.
• Fuel Compatibility: The 6.4L HEMI engine is versatile, running efficiently on both 89 and 87 octane gasoline, ensuring that the MDS system supports fuel economy without sacrificing performance.

This technology allows for improved fuel consumption without detracting from the engine’s power capabilities when they are required.

What is the origin and history of the 6.4L 392 HEMI engine?

The Origin and History of the 6.4L 392 HEMI Engine

Introduction to the 6.4L HEMI

In 2011, a significant development in automotive engineering was unveiled with the introduction of the 6.4-liter HEMI engine. This powertrain made its first appearance in the sporty lineup of American muscle cars. Its conception marked a leap forward from its predecessor, the 5.7-liter HEMI engine, by enhancing both power and performance.

Evolution and Adaptation

Initially launched for muscle cars, by 2014, the 6.4L HEMI engine found its place under the hood of more robust vehicles. Its versatility and power made it an ideal choice for heavy-duty trucks seeking enhanced towing capabilities. These trucks needed the kind of horsepower and torque that this engine could deliver, especially when compared to its smaller sibling, the 5.7L version.

Design and Performance

The architecture of the 6.4L HEMI took inspiration from the earlier 5.7L model, yet introduced advancements that catered to the needs of drivers requiring more power. This naturally aspirated V8 engine was crafted to provide not just higher speed and acceleration for cars, but also the strength necessary for hauling and towing tasks in larger trucks.

A Distinct Alternative

While turbocharged diesel engines often dominated the heavy-duty segment, the 6.4L 392 HEMI positioned itself as a powerful gasoline alternative. Its introduction provided truck owners who preferred gasoline engines with a viable option, balancing the expectations of power without the complexities of diesel systems.

In summary, the 6.4L 392 HEMI engine represents a convergence of innovation and adaptation, tracing its roots back to earlier HEMI engines but evolving to meet a broader range of automotive needs. Its legacy continues as a versatile powerhouse in the automotive world.

What materials are used in the construction of the 6.4L HEMI engine’s components?

Featuring all-forged internals, cross-bolted main journals, a nodular cast-iron block, and aluminum heads – Chryslerwent all out on what would become one of the best V8s on the block in some time. This powerhouse not only boasts impressive performance but also showcases meticulous craftsmanship in its construction materials.

Engine Construction Details

• Cylinder Block Material: Cast Iron
• Cylinder Head Material: Aluminum

These carefully chosen materials ensure durability and efficiency, forming the backbone of the 6.4L HEMI engine’s robust design. By combining the strength of cast iron with the lightweight properties of aluminum, Chrysler has crafted an engine that stands up to the rigors of high performance while maintaining optimal weight distribution.

Where is the engine manufactured?

The engine is produced at the Saltillo Engine Plant located in Ramos Arizpe, Mexico.

Who is the manufacturer of the engine?

The engine is manufactured by Chrysler.

What are the key design features of the 6.4L HEMI engine?

Chrysler currently produces the largest OE gasoline V8 engine commercially available, and it stuffs it in a multitude of vehicles from Dodge Chargers to RAM trucks. The 6.4L HEMI V8, known by the codename “Apache”, is a medium-duty 90-degree pushrod V8 with two large valves per cylinder, 16 spark plugs, 410 horsepower, and 429 ft-lbs of torque. Featuring all-forged internals, cross-bolted main journals, a nodular cast-iron block, and aluminum heads – Chrysler went all out on what would become one of the best V8s on the block in some time.

Key Design Features of the 6.4L HEMI

• Cylinder Block and Crankshaft: Built around a 90-degree, cast-iron cylinder block with a deep-skirt design, the 6.4L HEMI includes a forged steel crankshaft. This robust construction ensures durability and performance.
• Piston Cooling and Oil System: The engine block is equipped with piston cooling jets, which spray oil on the bottom of each piston to dissipate combustion heat. This feature is complemented by an oil-to-water oil cooler, enhancing the engine’s thermal efficiency.
• Connecting Rods and Pistons: Revised connecting rods made of high-strength powder metal and new, larger-diameter flat-top pistons contribute to the engine’s resilience and power output.
• Cylinder Heads: The aluminum heads house two valves and two spark plugs per cylinder, with an 11% increase in the intake port flow and a 13% increase in the exhaust port flow. These enhancements optimize the combustion process.
• Intake Manifold: The truck version of the 6.4L HEMI features an active dual-runner-length intake manifold, designed to boost low- and mid-range performance without sacrificing high-end power.
• Variable Valve Timing (VVT): A cam-in-block VVT system uses a hydraulic cam phasing mechanism, elevating the engine’s adaptability and efficiency across various speed ranges.
• Fuel Efficiency: The Multi Displacement System (MDS) deactivates four cylinders when full power isn’t required, improving fuel economy without compromising on capability. This system allows the engine to run on both 89 and standard 87 octane gasoline.

These meticulously crafted elements come together to form an engine that not only delivers impressive power but also maintains efficiency and reliability, making the 6.4L HEMI a standout in the world of V8 engines.

What type of fuel can the engine run on?

The engine can operate on both 89 octane and standard 87 octane gasoline.

What is the role of the variable valve timing (VVT) system in the engine?

The cam-in-block VVT system enhances engine performance by adjusting the valve timing through a hydraulic cam phasing system.

What systems are in place for optimizing fuel efficiency?

The engine uses a Multi Displacement System (MDS) that deactivates four cylinders during low power demand situations to reduce fuel consumption.

What types of intake manifolds are used in different applications of the engine?

SRT versions use a plastic intake manifold with shorter runners for high-speed performance, while truck versions have an active dual-runner-length intake manifold for balanced power across various speeds.

How are the cylinder heads designed, and how do they enhance performance?

The cylinder heads have two valves and two spark plugs per cylinder, with semi-hemispherical combustion chambers. They have enhanced port flow for improved intake and exhaust efficiency.

What materials and design features are used in the construction of the engine block and internals?

The 6.4L HEMI features a cast-iron cylinder block with cross-bolted main bearing caps, a forged steel crankshaft, piston cooling jets, and connecting rods made from high-strength powder metal.

What are the differences between the 5.7L and 6.4L HEMI engines?

The 6.4L HEMI differs from the 5.7L version in both bore diameter and stroke size, despite sharing the same 90-degree cast-iron block design.