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Wondering which diesel engine reigns supreme? We break down the Duramax, Powerstroke, and Cummins head-to-head across power, reliability, fuel economy, and tuning potential. Get the facts you need to choose the right diesel for your truck.
When it comes to heavy-duty diesel trucks, three names dominate the conversation: GM's Duramax, Ford's PowerStroke, and Ram's Cummins. Each has its loyal fanbase, and for good reason. But which diesel engine is actually the best for your needs? Whether you're towing a fifth-wheel, hauling equipment to the job site, or building a performance monster, understanding the differences between these powerplants is crucial.
At T3 Speed Shop, we've worked on countless diesel builds across all three platforms. We've seen them at stock power levels and pushed to their absolute limits. Here's our no-BS breakdown of how the Duramax, Powerstroke, and Cummins stack up in 2026.
Out of the box, all three diesel engines deliver serious grunt. But the devil is in the details—and the potential for more power.
Stock Output: 445 HP / 910 lb-ft
Tuning Potential: 550-650 HP with tuning and basic bolt-ons
The Verdict: The L5P Duramax is smooth, refined, and responds incredibly well to tuning. With a simple delete and tune (where legal), you're looking at substantial gains. The downside? GM's emissions systems can be restrictive, and the CP4.2 fuel pump has a reputation for catastrophic failures that can grenade the entire fuel system.
Stock Output: 475 HP / 1,050 lb-ft
Tuning Potential: 600-700+ HP with aggressive tuning
The Verdict: Ford's 6.7L Powerstroke leads the pack in stock torque output, making it a beast for towing right off the dealer lot. The single turbo setup is simpler than the Duramax, and aftermarket support is massive. However, the emissions systems are complex, and EGT management becomes critical when pushing serious power.
Stock Output: 400 HP / 1,000 lb-ft (High Output: 420 HP / 1,075 lb-ft)
Tuning Potential: 600-800+ HP with proper supporting mods
The Verdict: The Cummins inline-six is legendary for its durability and modification potential. The platform has decades of aftermarket development, and tuners have unlocked insane power from these engines. The straight-six design is inherently balanced and can handle abuse that would destroy lesser engines. If you're chasing 1,000+ HP, this is often the platform of choice.
Diesel engines are built to last, but not all are created equal. Here's what we've seen in terms of common issues and longevity.
Duramax: Solid engines but at times high failure rates with the 10-speed transmission. Also no longer an Allison backed transmission. DPF collapse at times.
Power Stroke: NEW 6.7L Power Strokes (2011-2014) had turbo issues, but Ford has addressed most gremlins in recent years. The emissions systems (SCR, DPF, EGR) are maintenance-intensive and expensive when they fail. Expect to budget for DEF system repairs after 150k miles. The engine itself, however, is stout. CP4.2 injection pumps have a high tendency to fail. There are upgrade options available that T3 Speed Shop can help with.
Cummins: The weak link is often the truck around it—specifically Ram's transmission options (the 68RFE). While the 6.7L Cummins itself is bulletproof, budget for transmission work if you tow heavy or tune aggressively. Common issues include grid heater failures that can take out the entire engine. The hydraulic lifters are weak and usually lead to engine full replacement. Hamilton Cam conversion kits are a great solution.
One of the main reasons people buy diesels is fuel economy. While all three get better mileage than their gas counterparts, there are differences.
Highway (Empty): Duramax: 20-24 MPG | Powerstroke: 18-22 MPG | Cummins: 17-22 MPG
Towing (10,000 lbs): Duramax: 12-14 MPG | Powerstroke: 10-13 MPG | Cummins: 10-12 MPG
The Duramax typically edges out the competition in fuel economy, thanks to its advanced engine management and lighter overall package. However, real-world results vary based on driving style, terrain, and load. All three will drink fuel when you're heavy on the throttle.
Diesel trucks are designed to move heavy loads, and all three deliver. The question is how they feel while doing it.
Duramax: Smooth power delivery and excellent transmission programming make the Duramax a comfortable tower. The GM platform offers excellent stability and refined ride quality. Max towing capacity on 2500/3500 models reaches 36,000+ lbs with proper configuration.
Power Stroke: The torque king. That 1,050 lb-ft rating means the Powerstroke pulls hard from low RPM, making it ideal for heavy fifth-wheel and gooseneck trailers. Ford's Super Duty chassis is engineered for heavy work, with max capacities exceeding 37,000 lbs. You'll feel the power.
Cummins: The Cummins pulls strong and steady, with a broad torque curve that makes towing effortless. However, the Ram chassis can feel less planted than the GM or Ford, especially in crosswinds. Max towing is competitive at 37,000+ lbs, but the coil-spring rear suspension sacrifices some stability for ride comfort.
For performance enthusiasts, aftermarket support is everything. Here's how the three platforms stack up for modifications.
Duramax: Strong aftermarket with tons of tuning options. Companies like EFI Live, HP Tuners, and countless others offer tunes and support. Turbos, injectors, CP3 conversions, and built transmissions are all readily available. The L5P is newer, so some parts availability lags behind older LML and LBZ platforms.
Power Stroke: Massive aftermarket. The 6.7L has been around since 2011, so there's a mature ecosystem of parts. Tuners like SCT, Bully Dog, and H&S offer everything from mild tunes to full race builds. Turbo upgrades and built transmissions are common.
Cummins: The Cummins has decades of aftermarket development, giving it the edge. From mild street tunes to 2,000+ HP drag builds, the parts and knowledge are out there. The platform is proven in competition pulling, drag racing, and sled pulling. If you want maximum modification potential, the Cummins is hard to beat.
Diesel trucks aren't cheap to buy or maintain. Here's what you need to budget for--- Everything.
Maintenance Costs: Diesel maintenance is more expensive than gas. Oil changes require 10+ quarts of synthetic oil, fuel filters need regular replacement, and DEF fluid is an ongoing expense. Budget $500-800 routine maintenance.
Repair Costs: Powerstroke EGR coolers and DPF replacements run $2,000-4,000. Cummins transmissions are $3,500-6,000 for a rebuild. Emissions systems across all three platforms are expensive to fix.
Resale Value: Diesel trucks hold value incredibly well, especially Cummins-powered Rams. A well-maintained diesel can sell for 60-70% of its original price after five years, compared to 50-55% for gas trucks.
Here's the truth: there's no single "best" diesel. It depends on what you prioritize.
Choose the Duramax: You want the best fuel economy, refined driving experience, and a well-integrated truck package. It's the most civilized daily driver of the three, with strong performance and great tech. Just address that CP4 pump risk.
Choose the Power Stroke: You need maximum torque for heavy towing and want a truck that pulls like a freight train. The Ford Super Duty chassis is built for serious work, and the 6.7L delivers the power to match. It's the towing champion.
Choose the Cummins: You want legendary durability, maximum modification potential, and the bragging rights that come with an inline-six. The Cummins will outlast the truck it's bolted to, and it's the go-to for anyone chasing big horsepower numbers. Just budget for transmission upgrades.
Whether you drive a:
Chevy Silverado HD or GMC Sierra HD with a Duramax
Ford Super Duty with a Powerstroke
Ram 2500, 3500, 4500, or 5500 with a Cummins
The best diesel engine is the one that fits your specific needs, budget, and driving style. Whether you're Team Duramax, Team Powerstroke, or Team Cummins, we've got the parts, tuning, and expertise to help you get the most out of your diesel. Also, diesel trucks retain value extremely well, light-duty and heavy-duty platforms.
Our team of diesel mechanics work on them every day.
From routine maintenance and diagnostics to full diesel air suspension upgrades, performance tuning, air and general diesel truck service in Salt Lake City, we’re experienced across all three diesel platforms.
Make your truck stronger, smoother, and more reliable — no matter what badge is on the grille.
Come visit us today at T3 Speed Shop!
