2018 Ram 3500 6.4L HEMI Specs: HP, Towing, Payload Charts

The 2018 Ram 3500 6.4L HEMI V8 makes 410 horsepower at 5,600 rpm and 429 lb-ft of torque at 4,000 rpm. Those two numbers only tell part of the story on a truck this configurable. Towing and payload change significantly depending on cab style, single rear wheel versus dual rear wheel setup, and axle ratio.

This guide breaks down the real 2018 Ram 3500 6.4L HEMI specs by configuration, covers which trims actually offered the engine, and compares it directly to the 6.7L Cummins so you know exactly what you are looking at before you buy or upgrade.

2018 Ram 3500 6.4L HEMI Engine Specs Explained

The 6.4L HEMI V8 is Ram’s top gas engine for the 2018 Heavy Duty lineup. It sits above the base 5.7L HEMI and below the 6.7L Cummins in both output and price.

The engine uses variable-valve timing to improve efficiency across the rpm range. It also runs Ram’s Multi-Displacement System, which shuts down four of the eight cylinders during steady highway cruising to save fuel without a noticeable change in how the truck drives.

What MDS Does For Fuel Economy

MDS works automatically in the background. Under light, steady throttle at highway speed, the engine switches to four-cylinder mode. Under acceleration, towing load, or hard throttle, all eight cylinders come back online instantly. The system is calibrated to be invisible to the driver in daily use.

That output only tells half the story. Where you could actually get the 6.4L HEMI in a 2018 Ram 3500 changes the picture.

Which 2018 Ram 3500 Trims Got the 6.4L HEMI

Some listings claim the 6.4L HEMI was Crew Cab only on the 2018 Ram 3500. Ram’s own factory towing guide shows that is not accurate.

The 6.4L HEMI was available across Regular Cab, Crew Cab Short Box, Crew Cab Long Box, and Mega Cab, in both 4×2 and 4×4, and in both single rear wheel (SRW) and dual rear wheel (DRW) configurations.

Trim availability was more limited than cab availability. The 6.4L HEMI came on:

• Tradesman
• Big Horn or Lone Star
• Laramie

Limited and Limited Longhorn 3500 models were diesel only in 2018. If you want the top-tier interior package, the 6.7L Cummins was the only engine offered. For comparison, the 2018 Ram 2500 6.4 HEMI specs show a similar trim split, but the 2500’s lighter chassis produces different payload numbers than what you get on a 3500.

Cab and trim only tell you what you could order. Towing and payload depend on the axle and cab configuration underneath it.

2018 Ram 3500 6.4L HEMI Towing and Payload By Configuration

This is where most spec pages give you one flattened number. The real figures move a lot depending on drivetrain, axle ratio, and whether you are looking at a pickup or a chassis cab. All figures below come from Ram’s official 2018 Ram 3500 trailer towing chart, rated to SAE J2807.

Pickup Towing and Payload

The Regular Cab dually with the 4.10 axle produces both the highest payload and the highest max trailer weight rating of any 6.4L HEMI pickup configuration. That 16,480-lb max trailer figure is the true ceiling for the gas engine. Some third-party sources cite a 30,000-lb fifth-wheel rating for the 6.4L HEMI, but that number belongs to the 6.7L Cummins High Output diesel, not the gas engine.

Chassis Cab Towing and Payload

Chassis cab models run a different frame and body configuration, so their numbers are separate from the pickup chart above.

The 4.44 axle trades a little payload for a noticeably higher GCWR and trailer rating, which matters if you’re upfitting for gooseneck or fifth-wheel work.

Those numbers only apply with the right transmission and axle underneath them.

66RFE Transmission and Axle Ratio Options Explained

Every 2018 Ram 3500 pickup with the 6.4L HEMI came standard with the 66RFE six-speed automatic. Chassis Cab models could also be ordered with the AS66RC medium-duty automatic for heavier-duty applications.

Two axle ratios were offered with the 6.4L HEMI:

• 3.73 axle favors fuel economy and lower engine rpm at highway speed, with a modest trade in max towing.
• 4.10 axle favors towing capacity and acceleration under load, at the cost of slightly lower highway fuel economy.

Four-wheel drive trucks used a BW 44-46 electric shift transfer case or a BW 44-47 manual shift transfer case, depending on trim and package.

With the hardware covered, the real question most 3500 shoppers ask is how this compares to the diesel.

How the 6.4L HEMI Compares to the 6.7L Cummins in 2018

The core tradeoff is simple. The 6.4L HEMI costs less to buy and service, while the 6.7L Cummins pulls harder and lasts longer under sustained heavy loads.

The 2018 6.7 Cummins specs show why the diesel wins on raw pulling power. It carries far more low-rpm torque, which matters most on long grades and heavy fifth-wheel trailers.

The 6.4L HEMI is better suited to shorter trips, moderate towing under roughly 15,000 lbs, and buyers who want to avoid diesel exhaust fluid, DPF regen cycles, and higher fuel costs. If you regularly tow near the 3500’s upper towing limits or need the highest GCWR available, the Cummins remains the stronger choice.

Engine choice aside, the HEMI’s own reliability track record is worth a straight answer too.

Is the 6.4L HEMI Reliable in the 2018 Ram 3500

The 6.4L HEMI has a strong reputation for long-term durability. FCA has stated the engine went through the same extended endurance testing program used for the Cummins diesel during development, though that claim comes from the manufacturer and should be read as a marketing data point rather than an independent study.

Forum owners commonly note that the HEMI runs well on short trips and stop-and-go driving, a scenario that can be harder on a diesel’s emissions system. Reported issues are more about maintenance items than major engine failures. For a full breakdown of known issues, see Ram 6.4 HEMI problems.

No NHTSA recall specific to the 6.4L HEMI engine itself was found for the 2018 Ram 3500. The truck was included in a broader tailgate actuator recall and a hydraulic control unit brake recall that year, but neither is tied to the engine.

What the 2018 Ram 3500 6.4L HEMI Numbers Mean For You

The 2018 Ram 3500 6.4L HEMI delivers 410 hp and 429 lb-ft, with a max payload of 7,350 lbs and max towing of 16,480 lbs in its strongest Regular Cab DRW configuration. It was available across every cab style that year, not just Crew Cab, though trim choice narrows to Tradesman, Big Horn, and Laramie.

If your towing stays under roughly 15,000 lbs and you want lower running costs, the 6.4L HEMI covers that job well. If you regularly push toward the 3500’s upper towing limits, step up to the Cummins. Either way, match your exact cab, drivetrain, and axle combination against the tables above before you buy or tow.

Frequently Asked Questions

What is the horsepower of the 2018 Ram 3500 6.4 HEMI?

The 2018 Ram 3500 6.4L HEMI makes 410 horsepower at 5,600 rpm and 429 lb-ft of torque at 4,000 rpm. This is Ram’s strongest gas engine offered that year on the Heavy Duty lineup.

Does the 2018 Ram 3500 6.4 HEMI come in Mega Cab?
Yes. Ram’s official towing data confirms the 6.4L HEMI was available in Mega Cab, along with Regular Cab and Crew Cab, in both SRW and DRW form. It was not limited to Crew Cab as some listings suggest.

What is the max towing capacity of a 2018 Ram 3500 6.4 HEMI?

The highest-rated pickup configuration, a Regular Cab dually with the 4.10 axle, tows up to 16,480 lbs. Towing drops meaningfully on Crew Cab and Mega Cab configurations with less rear axle weight rating.

Is the 6.4 HEMI or 6.7 Cummins better for the 2018 Ram 3500?

The 6.4L HEMI works well for moderate towing under roughly 15,000 lbs and lower running costs. The 6.7L Cummins offers far more torque and a higher GCWR ceiling for heavy fifth-wheel and gooseneck work.

How reliable is the 6.4L HEMI engine?

The 6.4L HEMI has a solid reputation for long-term durability, with most reported issues tied to maintenance items rather than major failures. No NHTSA recall specific to the engine itself was found for the 2018 model year.