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.

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 are the benefits of the MDS system in terms of parts and cost?

The MDS system reduces the number of parts needed, which enhances the engine’s reliability and lowers manufacturing costs.

What is the transition time for the cylinder deactivation system, and how is it achieved?

The system transitions in under 0.04 seconds by deactivating the valve lifters, thus minimizing energy loss during these quick changes.

How is the cylinder deactivation system integrated into the engine design?

The Multi Displacement System (MDS) is seamlessly integrated as part of the engine’s original design, ensuring it operates efficiently and reliably while maintaining simplicity.

What materials and design choices contribute to the engine’s efficiency and durability?

The engine is constructed with a deep-skirt design, featuring a cast iron block and a forged steel crankshaft. It also includes cross-bolted main bearing caps and aluminum heads, contributing to its durability and performance.

What additional efficiency features are present in the engine design?

The engine includes a cooled Exhaust Gas Recirculation (EGR) system, which enhances efficiency by reducing emissions and improving fuel economy.

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.

What are the power ratings of the SRT version?

The SRT version of the 6.4-liter engine typically delivers between 470 and 485 horsepower, along with 470 to 475 lb-ft of torque, providing a benchmark for performance in non-truck applications.

How does this engine differ from other similar engines?

Although it shares the same displacement with other 6.4-liter engines, this version is distinctively engineered for trucks, differing significantly in design and purpose from the SRT variants.

What is the primary application of the engine?

The engine is specifically designed for use in heavy-duty Ram trucks and chassis cabs, indicating its suitability for demanding tasks.