It’s just a fact of life. Sometimes truck size matters. The new lineup of Ram HD trucks just got extra beefy thanks to an improved diesel engine. The Cummins 6.7-liter turbo diesel is about to change the heavy-duty game. 

2025 Ram HD trucks have a new diesel engine 

The entire 2025 Ram HD truck lineup is available with a reworked Cummins diesel engine. The 6.7-liter V6 turbo diesel engine high output variant delivers 430 hp and 1,075 lb-ft of torque. It has an increase of 30 hp over the outgoing unit. 

The Cummins engine has a new intake manifold, a redesigned block and head, larger valves, and heavy-duty pistons. 

It’s equipped with advanced emissions air handling, a new high-pressure fuel delivery system, and improved serviceability. 

This engine provides faster acceleration, improved towing capabilities, is quieter, and reduces vibrations. Plus, it has improved cold-start management with advanced glow plug tech.

Stellantis has not released any figures related to fuel-economy improvements. However, the differential combo will provide higher efficiency and lower revs, especially at higher highway speeds. 

According to Stock Titan, the engine is paired with a new TorqueFlite eight-speed automatic transmission, top-feed dry service injectors, and a variable-geometry turbocharger. The heavy-duty trucks also feature a 3.42 rear-axle ratio and a maximum towing capacity of 36,610 lbs. 

The Ram 2055 and 3500 are still available with the 6.4- liter V8 Hemi that cranks out 405 hp and 429 lb-ft of torque. Also, the lower rear gear allows for a lower engine speed when you aren’t hauling a trailer. 

Of course, you can’t ignore the total refresh inside and out. Ram heavy-duty trucks have a new exterior style with split headlights and larger grilles. The interior features larger screens, dual wireless phone charging pads, safety upgrades, and improved furnishings.