2025 Diesel Dyno Shootout: Ford Power Stroke HO vs. L5P Duramax vs. Cummins 8-Speed
At Edge Products, pushing boundaries is what we do—whether it’s unlocking your truck’s potential with the CTS3 or strapping the latest powerplants to our dyno to see what they’re really made of. The 2025 model year brings some serious updates to the light-duty diesel segment, and we wanted to know: Which of the Big Three is putting down the most real-world power?
To find out, we gathered the top dogs from Ford, GM, and Ram and ran them bone-stock on our in-house chassis dyno. These were fresh-from-the-factory, unmodified trucks with break-in miles complete and topped off with the recommended fluids and fuel. No tricks. No tuning. Just raw, out-of-the-box numbers.
Let’s dive in.
The Contenders: What’s New for 2025
2025 Ford Power Stroke HO
Ford came out swinging this year with the updated High Output (HO) variant of the 6.7L Power Stroke. With redesigned internals, improved fuel delivery, and some clever calibration tweaks, this beast is advertised to deliver over 500 horsepower and 1,200 lb-ft at the crank. Pair that with Ford’s 10-speed TorqShift transmission, and you’ve got a recipe for brute force with responsive shifts.
2025 Chevrolet Silverado HD – L5P Duramax
Chevy’s tried-and-true 6.6L L5P Duramax returns for 2025, with minor updates to injection timing and transmission mapping. GM is focusing more on refinement and drivability this year rather than peak performance. It still pairs with the excellent Allison 10-speed, and while its spec sheet may seem familiar, this platform remains one of the most balanced in the class.
2025 Ram 2500 Cummins with 8-Speed Transmission
The biggest news out of Auburn Hills is Ram finally ditching the 6-speed in its 2500-series Cummins-powered trucks. The legendary 6.7L I6 Cummins now mates to a ZF-sourced 8-speed automatic, bringing faster shifts and better gear spread. While high output variants are still reserved for the 3500-series with Aisin, the 2500 benefits massively from the new gearbox. The torque numbers are climbing again, and efficiency gains are a welcome bonus.
The Numbers: Dyno Results
We tested all three trucks in identical conditions: same dyno, same fuel, same tire pressure, and ambient temperatures controlled within a few degrees.
Here’s how they stacked up:
2025 Ford Power Stroke HO 504HP/1,181lb-ft
2025 Chevrolet L5P Duramax 409HP/910lb-ft
2025 Ram Cummins (8-Speed) 403HP/996lb-ft
Analysis: Breaking Down the Results
Ford Power Stroke: King of the Hill
The Ford Power Stroke HO dominated the dyno with a staggering 504.2 horsepower at the wheels. Let that sink in—this is stock, emissions-compliant, pump diesel power. Torque didn’t disappoint either, coming in at an earth-twisting 1,181.6 lb-ft. That puts Ford comfortably ahead of the pack in both categories.
Ford’s aggressive calibration and turbo strategy deliver immense grunt across the entire powerband. You feel the pull early, and it doesn’t let up until well past 3,000 RPM. There’s little question that, for 2025, Ford is wearing the torque crown.
L5P Duramax: Smooth Operator
While not as powerful as the others, the L5P is no slouch. It put down 409.9 horsepower and 910.1 lb-ft of torque, staying true to GM’s philosophy of refined performance over brute strength. The Duramax delivers its power smoothly and consistently, with very little lag and excellent throttle response.
On the dyno, the L5P’s curve was the most linear of the three—flat, predictable, and perfect for towing or daily driving. It’s not the numbers king, but it’s an excellent real-world performer.
Ram Cummins: New Gearbox, Big Gains
The Cummins-powered Ram posted 403.5 horsepower and 996.2 lb-ft of torque, benefiting significantly from the new 8-speed automatic. Compared to the outgoing 6-speed version from previous years, we’re seeing faster ramp-up, smoother transitions, and less torque converter lag.
While the Cummins isn’t the peak performer in this test, its torque numbers are strong and arrive low in the RPM band. This makes it a killer for towing and low-end grunt. Add the better-shifting 8-speed into the mix, and you’ve got a powertrain that finally feels modern.
The Takeaway: Who Wins?
If it’s about numbers, Ford wins. Hands down. The Power Stroke HO is laying down dyno numbers that were once reserved for tuned trucks or race builds. But numbers aren’t the whole story.
The L5P Duramax continues to be a crowd favorite for balance and comfort, while the Cummins proves it still has life in it—especially now that it’s freed from the aging 68RFE.
Here’s how we see it:
Best Overall Power: Ford Power Stroke HO
Smoothest Power Delivery: Chevrolet L5P Duramax
Most Improved Drivetrain: Ram Cummins w/ 8-Speed
All three trucks bring serious performance to the table, and depending on your goals—towing, racing, daily driving—any one of them could be the right choice.
What’s Next: Tuning Potential?
While this dyno test focused on stock performance, you can bet we’re already working on unlocking more power from all three platforms with the Insight CTS3 support is always first and foremost and covers the Ford and GM already, with Ram coming soon. The Ford HO is ripe for tuning and our performance module releases in just a matter of weeks! The L5P we released support for in late 2024 and our 20202 EZ Module adds 63hp/130tq and is even CARB compliant for sale in all 50-states. We’re particularly excited about how the Cummins responds to tuning now that it finally has a transmission that can keep up.
Stay tuned as we release new tunes, data logs, and CTS3 updates for each of these platforms. The diesel wars are far from over—and at Edge, we’re here to help you stay ahead of the competition.
Final Thoughts
2025 is shaping up to be an exciting year for diesel performance. Whether you’re Team Blue, Bowtie, or Ram loyalist, there’s a lot to be proud of. At Edge Products, we’re thrilled to be part of the journey—giving you the tools to monitor, modify, and master your truck like never before.
Which truck impressed you the most? Have questions about tuning your 2025 diesel?
Drop a comment below or hit us up through our support channels. We’re here to help.
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