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Description
The 2025–2026 Ram 2500, 3500, 4500, and 5500 continue to use the familiar 6.7L Cummins inline-six, but these trucks represent one of the biggest mechanical updates Ram has made in years.
While the exterior refresh is obvious—with a redesigned grille, hood, headlights, and bumper—the real changes are buried under the hood and underneath the chassis. Ram and Cummins focused heavily on fixing long-standing weak points, improving drivability and power delivery, and modernizing the trucks without sacrificing the durability and character that diesel owners expect.
This generation targets three major goals. First, it addresses known problem areas such as transmissions and the infamous intake grid heater. Second, it improves power, responsiveness, and overall drivability, especially when towing.
Third, it refines noise, vibration, emissions behavior, and cold-start performance while keeping the engine reliable and serviceable for long-term ownership.
TRANSMISSION: TORQUEFLITE HD 8-SPEED AUTOMATIC
One of the most significant upgrades for 2025–2026 is the transmission. Ram has fully moved away from the long-criticized 68RFE and the Aisin option and standardized every Cummins truck on the ZF-built TorqueFlite HD 8HP75 eight-speed automatic. This transmission immediately puts Ram back into serious contention with Ford and GM, both in strength and in overall driving feel.
Compared to older Ram automatics, the 8HP75 offers faster, smoother shifts and a much wider and tighter gear spread. Adaptive shift logic allows the transmission to learn driver behavior, adjusting shift timing depending on whether the truck is unloaded, towing, or stuck in stop-and-go traffic.
Electronic Range Select gives the driver manual control to hold gears when descending grades or managing heavy trailers. The torque converter can lock up as early as first gear and remain locked through all eight gears, which improves power transfer, reduces heat, and helps with fuel economy under load. Smaller RPM drops between gears keep the engine in its sweet spot, especially when towing in hilly terrain.
The eight forward gears range from a deep 4.71:1 first gear to a 0.67:1 overdrive, paired with a 3.30:1 reverse. Four-wheel-drive models use a BorgWarner BW 44-48 part-time transfer case with 2WD, 4-High, 4-Low, and Neutral. Low range comes in at 2.64:1, making it easier to crawl off-road or maneuver heavy trailers at low speeds. Overall, this transmission completely changes how a Cummins-powered Ram feels, making it more responsive, more confident, and far less “lazy” than previous setups.
ENGINE: UPDATED 6.7L CUMMINS
At its core, the engine remains a 6.7L inline-six with 408 cubic inches of displacement, a 4.21-inch bore, and a 4.88-inch stroke. Compression sits at 16.2:1, and output climbs to 430 horsepower at 2,800 rpm with 1,075 lb-ft of torque at 1,800 rpm. High-idle can reach 3,200 rpm, oil capacity is 12 quarts with a filter, and the cooling system holds just under 24 quarts of coolant.
Where things get interesting is in the changes Cummins made to address past complaints and modern requirements. One of the biggest is the elimination of the intake grid heater. Older 6.7L engines relied on a grid heater plate mounted in the intake, which became notorious for bolt or nut failures that could destroy an engine if hardware entered a cylinder.
For 2025 and newer, Cummins switched to a multi-stage glow plug system similar to what Ford and GM have used for years. This improves cold-start performance, reduces intake restriction, and completely removes the grid heater failure risk.
The intake layout itself was also redesigned. Previous engines used a bulky plenum and a crossover manifold that wrapped around the cylinder head. The new design is more compact and resembles a factory side-draft intake, improving airflow and packaging without requiring major cylinder head changes.
While it still isn’t as free-flowing as high-end aftermarket manifolds at extreme boost levels, it is noticeably cleaner and more efficient than older stock setups.
Cummins also moved away from the compacted graphite iron block used in some earlier engines and returned to a traditional gray iron block. Many enthusiasts prefer this material for long-term durability and ease of machining.
The valvetrain remains a 24-valve, pushrod-actuated design with hydraulic lifters and a hydraulic roller cam. It stays quiet, requires minimal maintenance, and is more than capable of supporting towing and moderate performance upgrades. For longevity, cooling improvements and crankcase ventilation upgrades are still worthwhile. For higher power builds, head studs, stronger valve springs, and upgraded pushrods remain standard practice.
2025+ CUMMINS EXHAUST SYSTEM
The 2025–2026 Cummins does not use a radically redesigned exhaust-manifold casting compared to 2024 and earlier models, but it operates within a significantly improved exhaust-flow system. A new cylinder head features larger, reshaped exhaust ports and bigger exhaust valves, allowing exhaust gases to exit the combustion chamber with less restriction before reaching the manifold. This improved flow is paired with a revised Holset variable-geometry turbo that more efficiently uses exhaust energy, reducing backpressure and improving turbo response.
As a result, even with a similar-looking manifold, the 2025+ exhaust side runs more efficiently, with smoother spool-up and generally lower EGTs at stock or mildly tuned power levels. The improved head and turbo also provide a stronger baseline for future exhaust upgrades, meaning aftermarket manifolds or downpipes tend to deliver cleaner, more effective gains than on 2024-and-earlier 6.7L engines.
FUEL SYSTEM: CP3 PUMP AND PIEZO INJECTORS
The fuel system is another major leap forward for the 2025–2026 Cummins. These trucks use top-feed piezo injectors, replacing the older common-rail injector design used for decades. While still operating at extremely high pressures—over 30,000 psi—the piezo injectors offer far more precise control over injection timing and fuel delivery. The result is cleaner combustion, better fuel economy, more responsive power delivery, and lower exhaust gas temperatures.
Feeding those injectors is the new Bosch CP8 high-pressure pump. Historically, Cummins owners loved the CP3 used from 2003 to 2018, while the CP4 that followed gained a reputation for catastrophic failures across multiple brands. Ram temporarily returned to the CP3 from 2021 to 2024 as a stopgap solution.
The CP8 is a new-generation design intended to deliver higher pressures with improved reliability and control. While real-world longevity will take time to fully prove, it is not a simple rehash of the problematic early CP4 designs.
As with any modern high-pressure fuel system, a clean and consistent fuel supply is critical. Quality lift pumps and additional filtration from companies like FASS, AirDog, or Fleece are still highly recommended. They protect the CP8 and injectors, stabilize fuel pressure, and support tuning. It’s also important to note that injectors for this system are unique to the 2025–2026 platform and are not interchangeable with earlier 6.7L setups.
SUSPENSION AND STEERING UPDATES
Ram didn’t reinvent the suspension, largely because the existing design already rode and handled well for a heavy-duty truck. Four-wheel-drive models retain a 9.25-inch solid front axle with a center-axle disconnect, supported by radius arms, coil springs, and a track bar. For 2025 and newer trucks, optional adaptive steering improves on-center feel and stability, especially at highway speeds.
In the rear, the Ram 2500 can be equipped with either coil springs or a full air-ride system, while the 3500 uses leaf springs or leafs with factory air assist. Axle options include the AAM 11.5 or the heavier AAM 12.0 on Max Tow configurations. Common axle ratios include 3.42, with optional 3.73 and 4.10 gears for towing or larger tire setups.
From the factory, these trucks ride better than most heavy-duty competitors, but there are still compromises. Radius arms limit articulation, and stock shocks and steering components are tuned more for comfort than abuse. Over time, coils can sag, and joints can wear, leading to steering wander or even death wobble—especially with oversized tires or heavy front accessories.
Common upgrades include mild leveling kits, progressive-rate coils, better shocks, and improved steering stabilizers. For owners who tow heavy or run off-road regularly, aftermarket suspension systems from companies like Carli, Kryptonite, and ICON dramatically improve control and durability.
Rear airbags or upgraded springs are also popular for keeping the truck level under heavy fifth-wheel or gooseneck loads.
INTAKE, FILTRATION, AND AIRFLOW
From the factory, the intake system is designed primarily for noise reduction and emissions compliance. The closed airbox uses a snorkel and resonator to quiet turbo noise, and while it performs adequately at stock power levels, it quickly becomes a restriction once tuning, larger turbos, or heavy towing in hot conditions are introduced.
Aftermarket cold air intake systems from companies like S&B, Banks, and aFe offer improved airflow and reduced restriction while feeding cooler, denser air to the turbocharger. These systems typically improve throttle response, turbo spool, and exhaust gas temperatures.
For dusty environments or off-road use, many owners pair these intakes with pre-filter wraps or additional filtration stages to avoid sacrificing engine life for airflow. Reusable filters and simpler airbox designs also make routine service easier than with the factory setup. For tuned trucks or future turbo upgrades, a higher-flow intake quickly becomes a necessity rather than a luxury.
BIG PICTURE: DID RAM AND CUMMINS GET IT RIGHT?
Overall, the 2025–2026 Ram Cummins represents a major step forward. The new eight-speed transmission dramatically improves drivability and towing confidence. The revised 6.7L engine offers more power, better cold starts, and eliminates the grid heater failure risk entirely.
The fuel system is more modern and precise, though still worth protecting with proper lift pumps and filtration. The suspension remains one of the best-riding in the heavy-duty segment and is easy to refine with quality aftermarket parts.
While long-term data will ultimately decide how bulletproof the CP8 pump and 8HP75 transmission prove to be, early signs point to a well-engineered platform. For work trucks, tow rigs, and daily drivers alike, this generation looks like a solid foundation that finally fixes many of the complaints owners had about older Ram Cummins models.
Disclaimer: Diesel Power Products is not affiliated with Cummins or any of its subsidiaries or related companies. Unless a product is specifically identified as a Genuine Cummins product that has not been remanufactured, modified, or refurbished, Cummins makes no representation or warranty about the product and has not authorized, tested, or approved the parts for use in genuine Cummins brand products.