6.7 Cummins Standard Vs. High Output: What's The Difference?
Over the past 40-some years I've had the pleasure of towing trailers loaded with cattle, horses, furniture, cars, and, lately, nearly all of my worldly possessions as I traipse around the country towing my camper. To say I was excited when Ram introduced the High Output (HO) 6.7 Cummins in its 2019 HD pickup trucks would be an understatement, until I saw the price of those new trucks. However, I'm glad I didn't buy one then, because the HO 6.7 Cummins keeps getting better. Currently, the Ram 3500 ranks second for the most torque among diesel trucks in 2024.
I recently had the opportunity to test drive a 2024 Ram 3500 Dually equipped with the HO 6.7 Cummins and the power delivery was as impressive as I'd imagined it would be. However, the price difference between the HO Turbo Diesel and the Standard Output (SO) version made me wonder if the extra power (not a necessity in my situation) was worth it. After all, the SO 6.7 Cummins produces 370 horsepower compared to 420 horsepower from the HO, and 850 lb-ft of torque rather than 1,075. Overall, still very impressive numbers.
Other than more power, is the High Output 6.7 Cummins better than the Standard Output version?
The simple answer is yes. If you need to tow substantial loads, and you've decided on the Ram 3500, the HO 6.7 Cummins is the best engine option. For 2024, opting for the HO Cummins adds $2,800 to the price.
In addition to the 50 extra horsepower and the 225 lb-ft of torque gains, the HO Cummins is backed by a better transmission. The SO 6.7 Cummins comes equipped with the Chrysler 68RFE transmission, whereas the Aisin AS69RC transmission handles shifting duties in the HO-equipped Ram 3500 powertrain.
The downsides to the HO 6.7 Cummins option is that it is only available to HD Ram truck buyers in the 3500 models. So if you'd rather have a Ram 1500, or even the HD Ram 2500, with the HO Cummins you're out of luck. In fact, if you want a Ram truck with a diesel engine, you'll need to skip the Ram 1500 altogether.
What makes the HO 6.7 Cummins Turbo Diesel engine so good?
When the High Output 6.7 Cummins Turbo Diesel came out in Ram trucks in 2019 it was the first in the class to have 1,000 lb-ft of torque. Upon its introduction at the 2019 North American International Auto Show (NAIAS) in Detroit, Michigan, Cummins listed a number of improvements found in the next-generation HO 6.7 Turbo Diesel compared to the existing SO offering.
At the time, the new HO 6.7 Cummins featured an upgraded compacted graphite iron engine block to provide a basis to allow increased cylinder pressures. While the compression ratio within the cylinders dropped from 19:1 in the SO 6.7 to 16.2:1 in the new HO diesel engine, overall pressures increased due to the new, larger, turbocharger.
At the heart of the HO 6.7 Cummins power boost was the Cummins-Holset variable-geometry turbocharger. The new turbo featured heavy-duty bearings encased in a new style housing and the capability to produce boost pressures of up to 33 pounds per square inch (PSI). Other engine enhancements included a new cast iron cylinder head, exhaust valves capable of withstanding higher exhaust gas temperatures (EGT), self-adjusting hydraulic valve-lash adjusters, and an improved-alloy crankshaft.