Mopar Insiders posted in March about a diesel engine rumor concerning the 2025 Ram Heavy Duty lineup. Apparently, the truck brand would pare its two 6.7-liter Cummins turbodiesel engine options back to one, and that one engine would be more powerful than the most potent engine on sale today. Right now, Ram 2500 buyers can get a Standard-Output (SO) Cummins diesel making 370 horsepower and 850 pound-feet of torque, while 3500 buyers get to choose a High-Output (HO) version making 420 hp and 1,075 pound-feet of torque. MI credits "sources within the company" for confirmation of a single engine for next year, an insider hopes that "this engine will surpass the performance metrics of the current H/O variant, promising more power and torque."
For context, Ford's 6.7-liter Godzilla V8 diesel makes 475 hp and 1,050 lb-ft in base form, or 500 hp and 1,200 lb-ft in HO form. We suspect this is the one Ram's trying to get ahead of, Ram still putting huge effort into its Cummins branding and offerings, and having lifted the diesel's torque rating to 1,075 lb-ft in 2021 when Ford's lump was "only" putting out 1,050 lb-ft. Chevrolet's 6.6-liter Duramax diesel comes in one flavor, producing 470 hp and 975 pound-feet of torque.
As the product people say, the key enabler of Ram's rumored strategy is a new ZF Powerline eight-speed automatic transmission. It's slated to replace the base 68RFE and Aisin-sourced AS69RC transmissions used now, both of them six-speeds. Developed for Class 5-8 trucks with engines maxing out at maxing out at 1,000 lb-ft and GVWR's up to 57,000 pounds, we're told that its use in a heavy-duty pickup with much less vehicle weight GVWR will raise its torque cap. Transmission tech like "intelligent powershifts" s said to lower fuel use by as much as 10%, skip-shifting through gears is claimed to improve acceleration by up to 30%, and it's reported to weigh less than the six-speeds it replaces.
The diesel change would mean that 2500 buyers won't get left out of HO turbodiesel potency, probably a common gripe submitted to Ram HQ since Ford's HO Godzilla can be had on any Super Duty. The engine revision is coming with a refresh for the 2025 Ram HD lineup that will make the expected tweaks around the exterior, and might install the 14.5-inch Uconnect 5 system in the cabin. The 6.4-liter Hemi V8 making 410 hp and 429 lb-ft will continue to be the base engine.
