Ram 6.4L HEMI Specs: The Ultimate (Data-Driven) Guide

When evaluating heavy-duty trucks, the conversation is often dominated by the colossal torque figures of diesel engines. Yet, for a significant majority of truck owners, the standard-bearer for Ram’s Heavy-Duty lineup—the 6.4L HEMI V8—is the smarter, more practical, and more cost-effective workhorse While the 6.7L Cummins diesel gets the towing glory, the 6.4L HEMI is the unsung hero of payload, daily drivability, and long-term value.

This guide provides a data-driven dissection of the 6.4L HEMI’s technical specifications, real-world capabilities, and common owner-reported issues. It is designed to answer one critical question: Is this the right engine for you?

A Tale of Two HEMIs: Why “6.4L HEMI” Is a Confusing Term

The first point of confusion for many prospective buyers is the 6.4L HEMI” designation itself. The 6.4-liter (or 392-cubic-inch) displacement is a hallowed number in Mopar history, tracing its lineage back to the legendary first-generation FirePower HEMI in 1957.

However, the 6.4L HEMI found in a Ram 2500 is a fundamentally different engine than the 6.4L HEMI found in a Dodge Challenger, Charger, or Durango SRT.

• The SRT “Apache” V8: Debuting in 2011, this engine (code-named “Apache”) is a high-performance, high-horsepower engine built for acceleration. It uses a high 10.9:1 compression ratio and an aggressive camshaft to produce 470-485 horsepower.
• The Ram HD “BGE” V8: The truck version, which carries the “BGE” (Big Gas Engine) casting mark on its block, is optimized for a completely different mission: low-speed torque and extreme durability.

These differences are not superficial. To achieve its goal of low-end pulling power, the BGE variant uses a unique camshaft designed specifically for low-RPM torque. To enhance its durability for a lifetime of heavy-duty work, it employs a lower 10.0:1 compression ratio. This design results in lower peak horsepower but delivers its robust 429 lb-ft of torque at a very accessible 4,000 RPM.

This report will focus exclusively on the truck-based 6.4L HEMI “BGE” engine.

6.4L HEMI (BGE) vs. 6.4L HEMI (Apache/SRT) Specs

Specification	Ram HD "BGE" (Truck)	SRT "Apache" (Car/SUV)
Primary Goal	Low-Speed Torque & Durability	High-RPM Horsepower & Performance
Horsepower	405-410 hp @ 5,600 rpm	470-485 hp @ 6,000+ rpm
Torque	429 lb-ft @ 4,000 rpm	470-475 lb-ft @ 4,200+ rpm
Compression Ratio	10.0:1	10.9:1
Camshaft Design	Optimized for low-speed torque	Optimized for high-rpm horsepower
Key Applications	Ram 2500, Ram 3500	Dodge Challenger, Dodge Charger, Jeep Grand Cherokee SRT

Ram 6.4L HEMI (BGE) Engine Specifications: The "Work" Engine

The 6.4L BGE is engineered from the ground up for the stresses of heavy-duty applications. Its architecture prioritizes strength and longevity over all-out performance.

Core Architecture & Materials:

• Engine Block: The foundation is a durable cast iron block. While heavier than aluminum, this provides superior strength for withstanding high-load, high-torque conditions and forms a "strong foundation" for a work-truck engine.
• Cylinder Heads: The heads are made from 356 T6 aluminum, which saves weight on top of the engine and is highly effective at dissipating heat.
• Valvetrain: It uses a simple and robust Overhead Valve (OHV), or pushrod, design with two valves per cylinder (16 total).
• Crankshaft: The rotating assembly is built around a strong steel crankshaft.

Dimensions & Specifications:

• Displacement: 6.4 liters / 391-392 cubic inches
• Bore: 4.090 inches (103.9 mm)
• Stroke: 3.72 inches (94.6 mm)
• Compression Ratio: 10.0:1
• Fuel System: Sequential Multi-Point Fuel Injection (MPI)
• Firing Order: 1-8-4-3-6-5-7-2
• Engine Weight: Approximately 500 lbs (dry)

The engine's oversquare design (where the bore diameter is larger than the stroke length) typically favors high-RPM horsepower. This may seem contradictory to its low-torque mission. The technology that bridges this gap is Variable Cam Timing (VCT), which allows the engine to optimize valve timing across the RPM band. This gives the 6.4L HEMI its impressive flexibility, providing strong low-end pulling power without becoming asthmatic at higher RPMs.

Horsepower & Torque Specs by Model Year (Ram HD)

For the Ram 2500/3500, the 6.4L HEMI's output has remained remarkably consistent, a testament to its proven design.

• 2014-2024 Models (Ram 2500/3500/Power Wagon):
  • Horsepower: 410 hp @ 5,600 rpm
  • Torque: 429 lb-ft @ 4,000 rpm
• 2025 Model Year Update:
  • Horsepower: 405 hp
  • Torque: 429 lb-ft

This minor 5-horsepower drop for the 2025 model year is not due to a physical engine change but is almost certainly a result of updated emissions tuning and electronic calibration. It should be noted that Chassis Cab models or other fleet applications may be detuned to as low as 366 horsepower for specific duty cycles.

Key Technologies & Transmission Pairings

The 6.4L HEMI's performance is defined by two key technologies and, most importantly, its transmission.

• Variable Cam Timing (VCT): This is the engine's secret weapon for "consistent power across a wide torque band". By automatically advancing or retarding camshaft timing based on load and RPM, VCT ensures optimal efficiency and power delivery whether idling, towing, or cruising.
• Multi-Displacement System (MDS) / FuelSaver Technology: This is the engine's most controversial feature. Under light-load conditions, such as highway cruising, MDS deactivates four of the eight cylinders, effectively turning the V8 into a V4 to conserve fuel. While it provides a measurable (though debated) MPG benefit, it adds significant complexity via specialized hydraulic lifters. These specific lifters are the primary suspect in the engine's most notorious reliability problem: the "Hemi tick" and subsequent camshaft failure.

Transmission Evolution: A Critical Upgrade

The 6.4L HEMI was first introduced to the Ram Heavy Duty lineup in the 2014 Ram Power Wagon. The transmission paired with it is a critical factor for any potential buyer.

• 2014–2018: The 6.4L HEMI was paired with the 6-speed 66RFE automatic transmission. This was a capable and proven, if somewhat dated, gearbox.
• 2019–Present: Ram upgraded to the 8-speed ZF 8HP75-LCV automatic transmission.

This 2019 upgrade is arguably the single most important change in the 6.4L HEMI's history. The 8-speed ZF transmission is world-renowned for its refinement and intelligence. It features "on-the-fly shift mapping" and closer gear ratios, which dramatically improve acceleration, towing performance, and fuel economy. As one owner review notes, "the gear changes are seamless". When shopping for a used Ram 2500, a 2019+ model is far more desirable than a 2014-2018 model for this reason alone.

6.4L HEMI Towing & Payload Capacity (Ram 2500 & 3500)

This is the entire purpose of the BGE engine. Its specifications are a means to an end: providing best-in-class gasoline truck capability.

A critical trade-off exists between gas and diesel engines. The 6.4L HEMI engine is significantly lighter than its 6.7L Cummins diesel sibling. A truck's payload capacity is calculated by subtracting its curb weight from its Gross Vehicle Weight Rating (GVWR). Because the HEMI's curb weight is so much lower, it leaves more available capacity for payload.

The result is a clear verdict: the 6.4L HEMI loses to the Cummins on maximum towing but wins on maximum payload. This makes the 6.4L HEMI the best-in-class gas payload engine and the superior choice for users with heavy slide-in campers or those who frequently haul heavy materials in the bed.

• Ram 3500 (6.4L HEMI) Capability:
  • Maximum Payload: Up to 7,680 pounds (2024 models) or 7,590 pounds (2025 models).
  • Maximum Towing: Up to 18,150 pounds.
• Ram 2500 (6.4L HEMI) Capability:
  • Maximum Payload: Up to 4,420 pounds.
  • Maximum Towing: Up to 17,750 pounds.

2025 Ram 2500 & 3500 Max Gas Payload/Towing (6.4L HEMI)

Model	Max Payload	Required Configuration (2025)	Max Towing	Required Configuration (2025)
Ram 2500	4,680 lbs	4x2 Mega Cab, 6'4" Bed	17,750 lbs	4x2 Regular Cab, 8' Bed
Ram 3500	7,590 lbs	4x2 Regular Cab, 8' Bed (DRW)	18,150 lbs	4x2 Regular Cab, 8' Bed (DRW)

Real-World 6.4L HEMI MPG: What Owners Actually Get

Heavy-duty trucks are not rated for fuel economy by the EPA, so all figures are based on real-world owner reports. These figures are highly variable.

• City/Stop-and-Go: 10-12 MPG is a commonly reported average. Some owners see up to 14 MPG in mixed, light-traffic driving.
• Highway (Unloaded): This is the most surprising figure. Many owners report 16-19+ MPG. This is achievable only by keeping speeds low (around 63-65 mph), which allows the Multi-Displacement System (MDS) to remain active.
• Towing (Heavy, ~10,000-12,000 lbs): 7-9 MPG is the consistent reality of towing heavy with a large gas V8.

Two factors have the greatest impact on these numbers:

1. Axle Ratio (3.73 vs 4.10): Owners with 3.73 axle gears are the ones who typically report the 19+ MPG highway figures. The 4.10 axle (standard on the Power Wagon) provides better towing leverage but will result in lower unloaded MPG.
2. Speed: This is the single biggest variable. One owner report noted 20 MPG at 65 mph, which plummeted to 15-16 MPG at 78 mph. The engine's efficiency, and the MDS's effectiveness, fall off a cliff at higher highway speeds.

6.4L HEMI Real-World Fuel Economy (Owner-Reported)

Driving Condition	Reported MPG	Key Factors
City (Stop-and-Go)	10-14 MPG	Heavy traffic, frequent stops
Highway (< 70 mph)	16-19+ MPG	MDS active, 3.73 axle ratio
Highway (> 70 mph)	15-16 MPG	MDS less active, wind resistance
Towing (10k+ lbs)	7-9 MPG	Trailer weight, hills, speed

6.4L HEMI Reliability, Lifespan, and Common Problems

The 6.4L HEMI BGE is generally considered a "robust engine" and a "reliable work-horse". With proper maintenance, owner reports of 150,000-200,000 miles are common, and many examples run far longer.

However, no engine is without its faults. The #1 concern for any 6.4L HEMI owner is the notorious "Hemi tick". This is a rhythmic ticking sound, and it is crucial to diagnose which tick is present.

The "Hemi Tick": What It Is (and Isn't)

1. Cause 1 (Harmless): Fuel Injector Noise. The multi-port fuel injectors make a light, fast "ticking" sound as they operate. This is 100% normal engine operation and is not a sign of a problem.
2. Cause 2 (Common/Annoying): Exhaust Manifold Leak. The exhaust manifold bolts (a common Mopar V8 issue) can break, causing a small exhaust leak. This creates a "ticking" sound that is often loudest when the engine is cold and may quiet down as the metal expands and seals the gap.
3. Cause 3 (Severe): Lifter & Camshaft Failure. This is the "real" Hemi tick. It is a deeper, more metallic tick or light knock caused by a failed hydraulic lifter. The needle bearings inside the lifter's roller fail, causing the lifter to stop spinning and "eat" the camshaft lobe. This catastrophic failure sends metal particles throughout the engine, often requiring a full engine replacement.

Deep Dive: Why Do 6.4L HEMI Lifters Fail?

Data from owner reports and mechanic reviews points to a "perfect storm" of three factors that lead to lifter failure:

1. The MDS System: The Multi-Displacement System requires complex, deactivating lifters, which are a known weak point and potential failure point.
2. Extended Idling: The most common advice from long-time owners is to "avoid extended idling". This is believed to cause a "lack of oil to the lifters at idle". On a cold start or at low-RPM idle, the lifters and camshaft are among the last components to receive full oil pressure.
3. The HD Truck Use Case: Ram HD trucks are work trucks. They are used by fleets, plowers, and utility workers who let their trucks idle for hours on job sites.

This creates a causal chain: the truck's intended use case (extended idling) directly attacks the engine's known design weakness (MDS lifters) by creating the condition it hates most (low-RPM oil starvation).

How to Prevent 6.4L HEMI Lifter Failure

1. Do NOT Let It Idle: This is the most critical preventative step. Avoid extended idling (over 10-15 minutes) whenever possible.
2. Use High-Quality Oil: Use the exact specified 0W-40 full synthetic oil and do not extend oil change intervals.b Proper lubrication is the best defense.
3. Owner-Endorsed Fix: Some owners have reported installing the higher-volume oil pump from an SRT model to force more oil to the top end at idle, though this is not a factory-endorsed solution.

6.4L HEMI Maintenance Schedule & Costs

Proper maintenance is the key to this engine's longevity.

6.4L HEMI Oil Type & Capacity

• Oil Type: 0W-40 Full Synthetic (API SP grade).
• Oil Capacity: 7.0 Quarts (with filter).
• Oil Drain Plug Torque: 25 ft-lbs.
• External Source: Using a high-quality, API-certified synthetic oil is required.(https://www.amsoil.com/lookup/auto-and-light-truck/2022/ram/2500-pickup/6-4l-8-cyl-engine-code-j-esb-j/).

6.4L HEMI Spark Plug Change Interval

• Quantity: 16 spark plugs (two per cylinder).
• Change Interval: 100,000 miles.

Fuel Recommendation

• Octane: 89 Octane is recommended for optimal performance. 87 Octane is acceptable for use.

6.4L HEMI Maintenance Specs & Schedule

Item	Specification	Interval / Torque
Engine Oil Type	0W-40 Full Synthetic	4,000 - 6,000 miles (or per oil life monitor)
Engine Oil Capacity	7.0 Quarts (with filter)	N/A
Oil Drain Plug Torque	25 ft-lbs	N/A
Spark Plugs	16 total (2 per cylinder)	100,000 miles
Fuel Requirement	89 Octane Recommended / 87 Acceptable	N/A
Coolant	Mopar 10-year / 150,000-mile	10 years / 150,000 miles
Transmission Fluid	8-Speed 8HP75-LCV	60,000 miles

6.4L HEMI vs. The Competition (Gas & Diesel)

This is where the 6.4L HEMI's value proposition becomes clear.

6.4L HEMI vs. Ford 7.3L "Godzilla" vs. GM 6.6L "L8T"

This is the modern gas HD V8 showdown. On paper, the 6.4L HEMI (410 hp / 429 lb-ft) is the "weakest" of the three. The Ford 7.3L "Godzilla" V8 produces 430 hp and 475 lb-ft of torque, while the GM 6.6L "L8T" V8 makes 401 hp and 464 lb-ft of torque.

However, an engine's specs do not tell the whole story. The Ram 2500's platform advantages are what set it apart. Its class-exclusive 5-link coil-spring rear suspension and the superb 8-speed ZF transmission give it a widely praised advantage in ride comfort and on-road refinement that the leaf-spring-equipped Ford and GM trucks cannot match.

The buying decision is a clear trade-off: The Ford 7.3L offers best-in-class gas torque. The Ram 6.4L offers the best ride comfort and gas payload. The GM 6.6L is a proven, direct-injection workhorse.

Gas HD V8 Engine Comparison (Ram vs. Ford vs. GM)

Specification	Ram 6.4L HEMI	Ford 7.3L "Godzilla"	GM 6.6L "L8T"
Displacement	6.4 Liters	7.3 Liters	6.6 Liters
Horsepower	410 hp	430 hp	401 hp
Torque	429 lb-ft	475 lb-ft	464 lb-ft
Block Material	Cast Iron	Cast Iron	Cast Iron
Valvetrain	OHV / Pushrod	OHV / Pushrod	OHV / Pushrod
Fuel System	MPI (Multi-Point)	PFI (Port)	DI (Direct Injection)
Transmission	8-Speed Auto (ZF)	10-Speed Auto (TorqShift)	10-Speed Auto (Allison)

6.4L HEMI vs. 6.7L Cummins: The In-House Dilemma

This is the most common decision for a Ram buyer.

• Towing & Payload: As established, the 6.7L Cummins is the towing king, rated for over 37,000 lbs in some 3500s. The 6.4L HEMI is the payload king, maxing out at 7,680 lbs, which is significantly more than a diesel can offer.
• Towing MPG: The Cummins is far more efficient while towing. Owner reports show the Cummins getting 11.6-14 MPG towing the same load that a HEMI gets 8-10 MPG on.
• Total Cost of Ownership (The "Diesel Myth"): The long-held belief that a diesel's fuel savings will pay for its high upfront cost is no longer a guarantee.
  • Upfront Cost: The Cummins is a $9,000-$11,000 option.
  • Maintenance: Diesel maintenance is far more expensive. It requires 12-quart oil changes (vs. 7 for the HEMI), mandatory fuel filter changes, and Diesel Exhaust Fluid (DEF).
  • Fuel Cost: Even with better MPG, the higher price of diesel fuel can erase the savings. One analysis showed that for a heavy commuter, the net annual fuel savings of a Cummins could be less than $1,800.
  • The Breakeven Point: When factoring in the high upfront cost, higher fuel price, and more expensive maintenance, one owner concluded you would have to drive a "ridiculous amount" of miles to actually hit the breakeven point.

Final Verdict: Is the Ram 6.4L HEMI the Right Engine for You?

The 6.4L HEMI BGE is a proven, powerful, and capable engine. Its "best-in-class" titles just aren't the ones that grab headlines.

You should buy the 6.4L HEMI if:

• You are the "Payload King": You need to haul a heavy slide-in truck camper or carry thousands of pounds of tools and materials in the bed. The HEMI's 7,680 lb max payload is superior to the diesel's.
• You are the "Occasional Tower": You tow a boat, travel trailer, or equipment trailer under 15,000 lbs a few times a year. The HEMI has more than enough power and saves you over $10,000 upfront compared to the diesel.
• You value comfort: You want a heavy-duty truck that serves as a comfortable daily driver. The HEMI, paired with the 8-speed ZF transmission and 5-link coil-spring suspension, provides a best-in-class ride.

You should AVOID the 6.4L HEMI if:

• You are the "Heavy Hauler": You regularly tow 18,000+ lb fifth-wheel or gooseneck trailers. You need the low-end torque and towing stability of the 6.7L Cummins. Period.
• You are a "Fleet Idler": Your truck will be a work-site or plow truck that idles for hours every day. The known risk of lifter failure from extended idling makes this a poor choice for that specific use case.

For more information on the Gen-III HEMI family,(https://www.dodgegarage.com/news/article/how-to/2020/10/gen-iii-hemi-engine-quick-reference-guide-part-iv).

Frequently Asked Questions (FAQ)

Q: What is the horsepower and torque of the Ram 6.4L HEMI?

A: In Ram 2500/3500 trucks (model years 2014-2024), the 6.4L HEMI (BGE) produces 410 horsepower @ 5,600 rpm and 429 lb-ft of torque @ 4,000 rpm.1 2025 models are rated at 405 hp and 429 lb-ft.

Q: What kind of oil does the 6.4L HEMI take?

A: The Ram 6.4L HEMI requires 7.0 quarts (with filter) of 0W-40 full synthetic motor oil that meets API SP-grade standards.

Q: Is the 6.4L HEMI reliable?

A: Yes, it is generally considered a reliable and robust workhorse engine.4 Its main weakness is the "Hemi tick," which can be caused by severe lifter/camshaft failure. This risk is primarily linked to extended idling and failing to use the correct 0W-40 synthetic oil.

Q: How often do you change spark plugs on a 6.4L HEMI?

A: The recommended service interval for the 6.4L HEMI's 16 spark plugs is every 100,000 miles.

Q: What is the difference between the 6.4L HEMI and the 7.3L Godzilla?

A: Both are pushrod, cast-iron block V8s. The Ram 6.4L HEMI (410 hp / 429 lb-ft) is paired with an 8-speed auto and offers better ride comfort via a coil-spring suspension. The Ford 7.3L "Godzilla" (430 hp / 475 lb-ft) produces more torque and is paired with a 10-speed auto.

Q: Is the 6.4L HEMI better than the 6.7L Cummins?

A: It is "better" for payload and has a much lower total cost of ownership.15 The 6.7L Cummins is significantly better for heavy towing (over 18,000 lbs) and long-distance towing fuel economy.