The Detroit DD15 is a 14.8-liter inline six-cylinder heavy-duty diesel engine built by Detroit Diesel. It produces between 400 and 505 horsepower and 1,250 to 1,750 lb-ft of torque, depending on the rating. The DD15 has a cast iron block, an amplified common rail fuel system, and a variable geometry turbocharger. It first launched in 2007 as the replacement for the Detroit Series 60 and powers Class 8 trucks like the Freightliner Cascadia and Western Star models.
That short answer covers the basics. The rest of this guide breaks down every DD15 specification in detail: power ratings, dimensions, weight, fuel system, oil and coolant capacities, emissions equipment, and the truck models that run it. Whether you are replacing an engine or verifying specs before you buy, this page has the numbers you need.
What Is the Detroit DD15 Engine?
The Detroit DD15 is the flagship heavy-duty engine in Detroit's DD platform. Detroit Diesel introduced it in 2007 to replace the legendary Series 60, which had powered heavy trucks for two decades but could no longer meet tightening EPA emission rules.
The DD15 quickly became one of the most common engines in North American long-haul trucking. It is known for strong low-end torque, good fuel economy for its class, and a reputation for durability past 1 million miles when maintained well.
HD Engines has supplied Detroit diesel engines for more than 25 years. You can view current DD15 inventory on our Detroit DD15 engines collection page, where each listing shows the serial number, horsepower, emissions rating, and engine family.
Looking for the right DD15 engine? Our experts will match the correct rating using your engine family number before purchase.
Detroit DD15 Engine Specs at a Glance
Here are the core Detroit DD15 specifications every buyer should know:
- Engine type: Inline 6-cylinder, 4-stroke diesel
- Displacement: 14.8 liters (904 cubic inches)
- Bore and stroke: 139 mm x 163 mm (5.47 in x 6.42 in)
- Horsepower range: 400 to 505 hp
- Torque range: 1,250 to 1,750 lb-ft
- Compression ratio: 18.4:1 (varies slightly by model year)
- Dry weight: approximately 2,880 lb (1,306 kg)
The DD15 uses a cast iron block and a single overhead camshaft cylinder head. Its Amplified Common Rail System (ACRS) delivers precise fuel injection at high pressure, which improves both combustion efficiency and fuel economy.
Detroit DD15 Horsepower and Torque Ratings
The DD15 comes in several factory power ratings. The rating is set by the ECM calibration, so two physically identical engines can carry different horsepower depending on the tune.
Common DD15 ratings include 400 hp, 435 hp, 455 hp, 475 hp, and 505 hp. The 505 hp version is the most popular for long-haul applications because it pairs high horsepower with 1,750 lb-ft of torque for pulling heavy loads at highway speed.
Lower ratings around 400 to 435 hp are common in regional and vocational trucks where fuel economy matters more than peak power. If you need help matching a DD15 rating to your truck, our team can guide you based on your VIN and application.
Detroit DD15 Dimensions and Weight
Physical size matters when you are planning an engine swap. The DD15 is a large, heavy engine designed for Class 8 chassis.
- Length: approximately 55 inches
- Width: approximately 38 inches
- Height: approximately 51 inches
- Dry weight: approximately 2,880 lb
Because of its weight and size, the DD15 ships on a freight pallet with liftgate service. Confirm your shop has a forklift or engine hoist rated for at least 3,000 lb before delivery.
Detroit DD15 Fuel System and Turbocharger
The DD15 uses the Amplified Common Rail System, a high-pressure fuel injection setup that Detroit developed for cleaner, more efficient combustion. The system meters fuel precisely at each injector, which improves throttle response and reduces waste.
Air is fed by a variable geometry turbocharger (VGT). The turbo's adjustable vanes let the engine build boost quickly at low RPM and maintain efficiency at cruise. On newer generations, Detroit switched to a fixed geometry ball-bearing turbo that spools faster for even better response.
Fuel injector and turbo problems are among the more common DD15 repairs. When a turbo fails and sends debris downstream, the damage can force a full engine replacement rather than a simple part swap.
Detroit DD15 Oil and Coolant Capacities
Keeping the DD15 within spec on fluids is the single biggest factor in how long it lasts. Here are the key capacities:
- Engine oil capacity: approximately 42 quarts (10.5 gallons) with filter
- Recommended oil: full-synthetic 10W-30 meeting Detroit spec 93K222
- Coolant capacity: approximately 40 quarts (engine only, more with full cooling system)
- Oil change interval: up to 50,000 miles on long-haul with premium synthetic and Detroit Connect monitoring
Always confirm the exact capacity against your engine's specific model year, since intervals and volumes changed slightly across generations.
Detroit DD15 Emissions and Aftertreatment
Every DD15 built after 2010 uses a full aftertreatment system to meet EPA and GHG standards. This includes a diesel particulate filter (DPF), selective catalytic reduction (SCR), and diesel exhaust fluid (DEF).
The emissions rating is stamped on the engine and matters a lot when buying used. A truck registered for on-highway use needs an engine with the matching EPA certification, such as EPA10, EPA13, or EPA17. Installing the wrong emissions-rated engine can create compliance and registration problems.
When you buy from HD Engines, every DD15 listing shows the exact emissions rating so you can match it to your truck before you order.
Not sure which DD15 emissions rating fits your truck? Our experts will verify the correct engine using your VIN information.
Which Trucks Use the Detroit DD15 Engine?
The DD15 is used almost exclusively in Daimler Truck North America chassis. The most common applications are:
- Freightliner Cascadia (the most common DD15 truck)
- Freightliner Coronado
- Western Star 4900, 5700, and 49X
If you drive a Cascadia or Western Star and need a replacement, a DD15 from the same emissions generation is usually a direct fit. Our team can verify compatibility from your truck's build year and engine family number.
Is the Detroit DD15 a Reliable Engine?
Yes. The DD15 has a strong reputation for reliability, with many engines running past 1 million miles before a major overhaul. Its cast iron block and robust rotating assembly are built for the long haul.
Like any heavy-duty engine, it has known weak points. The EGR cooler, aftertreatment sensors, and turbo actuator are the parts most likely to need attention. Staying on top of oil changes and DEF quality prevents most major DD15 failures.
When a DD15 does reach the end of its service life, a run-tested replacement engine is often more cost-effective than a full in-frame rebuild, especially on higher-mileage trucks.
How the DD15 Compares to Other Heavy-Duty Engines
The DD15 competes with a small group of 15-liter class engines. Each has trade-offs in power, fuel economy, and parts availability.
The Cummins ISX15 is the DD15's closest rival, popular for its wide parts network and proven durability across many truck brands.
The Volvo D13 is a 13-liter option favored for fuel economy in Volvo and Mack chassis, though it makes less peak torque than the DD15.
The Paccar MX-13 powers many Peterbilt and Kenworth trucks and is a lighter 13-liter alternative for weight-sensitive fleets.
Within Detroit's own lineup, many buyers compare the DD15 vs. DD13 when choosing an engine for their application. The Detroit DD13 is a lighter 12.8-liter engine better suited to regional hauling, while the Detroit DD16 is the heavy-spec option for the most demanding vocational and heavy-haul work.
What to Check Before Buying a Used DD15
A used DD15 can save you tens of thousands compared to new, but only if you verify the engine first. Check these details on any listing:
- Engine serial number and family number, matched to the listing
- Emissions rating (EPA10, EPA13, or EPA17) matched to your truck
- Documented hours or mileage and a run-test report
- Horsepower rating confirmed against your application
Detroit engines are just one part of a large inventory. Whether you need a DD15 or a different brand, you can browse the full range of our main Detroit collection or explore engines from other manufacturers.
Start with our complete Detroit diesel engines collection, or view every engine we carry on the full engine inventory page.
Detroit DD15 Specs: Frequently Asked Questions
How much horsepower does a Detroit DD15 have?
The Detroit DD15 produces between 400 and 505 horsepower depending on the ECM rating. The 505 hp version with 1,750 lb-ft of torque is the most common for long-haul trucks.
What is the displacement of the Detroit DD15?
The DD15 has a displacement of 14.8 liters (904 cubic inches) from an inline six-cylinder configuration with a 139 mm bore and 163 mm stroke.
How much does a Detroit DD15 engine weigh?
A Detroit DD15 weighs approximately 2,880 pounds (1,306 kg) dry. Plan for lifting equipment rated above 3,000 pounds when handling the engine.
How many miles does a Detroit DD15 last?
With proper maintenance, a Detroit DD15 commonly lasts 800,000 to over 1,000,000 miles before needing a major overhaul. Regular oil changes and clean DEF are the biggest factors in longevity.
What oil does a Detroit DD15 take?
The DD15 uses full-synthetic 10W-30 oil meeting Detroit specification 93K222, with a capacity of about 42 quarts including the filter.
What trucks have the Detroit DD15 engine?
The DD15 is used in the Freightliner Cascadia and Coronado, and the Western Star 4900, 5700, and 49X. The Freightliner Cascadia is by far the most common DD15 application.
Get the Right Detroit DD15 Engine From HD Engines
HD Engines has supplied tested diesel engines since 1998 from our facility in Hialeah, Florida. Every DD15 we sell is inspected, listed with full specs, and backed by our team's help matching the right engine to your truck.
Ready to buy or need a quote? Contact HD Engines with your VIN or engine family number. Call (786) 377-5210 or email info@hdengines.com and we will match you with the right DD15.