Complete Engine Guide for International Trucks | S13 Integrated Powertrain vs. Cummins B6.7, L9, and X15
There’s a moment of quiet confidence when you turn the key and feel the powertrain respond exactly as you expect—whether you’re pulling a heavy load up a grade or navigating a tight jobsite.
TL;DR
International offers two distinct engine paths: the in-house S13 Integrated Powertrain and a lineup of proven Cummins engines. The S13 is a clean-sheet 12.7L design that eliminates EGR hardware and uses a dual-stage aftertreatment system, delivering up to 515 hp and 1,850 lb-ft of torque with industry-leading fuel economy. It’s paired with the T14 14-speed automated transmission for full integration. For medium-duty applications, the Cummins B6.7 (6.7L, up to 300 hp) and L9 (8.9L, up to 380 hp) offer proven reliability, while the X15 (14.9L, up to 675 hp) remains the heavyweight choice for maximum power. The S13 is also EPA 2027-ready with 90% parts commonality, making it the future-focused choice.
Key Takeaways
- S13 Integrated Powertrain: International’s proprietary 12.7L engine with no EGR cooler, dual-stage aftertreatment, and integrated T14 transmission. Delivers up to 515 hp and leads the on-highway aero category in fuel economy by at least 5%.
- Cummins B6.7: A 6.7L medium-duty workhorse offering 200-300 hp and 600-660 lb-ft of torque. The new B6.7 Octane is Cummins’ first gasoline-powered engine.
- Cummins L9: An 8.9L engine with 260-380 hp and up to 1,250 lb-ft of torque. Known for its power-to-weight ratio and over 35 years of production history.
- Cummins X15: A 14.9L heavy-duty engine with 400-500 hp (Efficiency Series) up to 675 hp (Performance Series) and up to 2,050 lb-ft of torque.
- EPA 2027 Readiness: The S13 was designed with future regulations in mind, carrying over 90% of components for the 2027 model year.
The S13 Integrated Powertrain: International’s Clean-Sheet Design
The S13 Integrated Powertrain represents a fundamental shift in how International approaches diesel power. Developed from a clean sheet of paper in collaboration with the TRATON Group, it’s the first engine International designed with selective catalytic reduction (SCR) technology as the primary emissions reduction method.
What Makes the S13 Different?
The most striking feature of the S13 is what it doesn’t have: an EGR cooler. By eliminating cooled exhaust gas recirculation, the engine can flow 100% of exhaust to the turbocharger during normal operation. This means more power, improved performance, and less soot generation.
Key Engine Specifications:
| Specification | Detail |
|---|---|
| Displacement | 12.7L |
| Configuration | Inline 6-Cylinder |
| Horsepower | Up to 515 hp |
| Torque | Up to 1,850 lb-ft |
| Compression Ratio | 23:1 |
| Aspiration | Fixed Geometry Turbocharger |
| Dry Weight | 2,284 lbs |
| B10 Design Life | 1,200,000 miles |
The 23:1 compression ratio is among the highest in the industry, ensuring a more complete fuel burn. This allows the high-pressure fuel pump to operate at a lower pressure (1,800 bar) while still delivering excellent performance.
The T14 Transmission: Built to Match
The T14 is a 14-speed overdrive automated manual transmission designed in-house specifically for the S13 engine. It features a unique planetary gear set for reverse, reducing weight and size. The electronically controlled clutch actuator delivers faster, smoother shifts and doesn’t consume air during complex maneuvers.
Transmission Highlights:
- 14 speeds with 2 crawler gears
- Deep low-end gearing with shifting smoothness
- Direct drive in 13th gear for peak fuel economy
- Integrated oil-to-water coolant system
- Vocational modes including paver, off-road, and split shaft
Aftertreatment: Simpler and More Reliable
Because the S13 generates less soot through its clean combustion cycle, the engineers eliminated the need for a diesel oxidation catalyst (DOC). The dual-stage aftertreatment system injects DEF in two stages and reduces NOx without the complexity of EGR. The result is extended service intervals and no active regens.
How does this compare to the trusted Cummins lineup?
Cummins B6.7: The Medium-Duty Workhorse
The B6.7 is Cummins’ legendary 6.7L engine platform, powering millions of medium-duty trucks worldwide. It’s available in International’s MV and CV Series trucks for applications like delivery, municipal service, and utility work.
B6.7 Key Specifications:
| Specification | Detail |
|---|---|
| Displacement | 6.7L |
| Horsepower | 200-300 hp |
| Torque | 600-660 lb-ft |
| Governed Speed | 3,200 rpm |
| Dry Weight | 1,301 lbs |
The B6.7 platform has earned a reputation for durability and reliability across the most challenging duty cycles. It features high-pressure common rail fuel injection and is compatible with B20 biodiesel.
The B6.7 Octane: A New Option
Cummins recently introduced the B6.7 Octane, which is the company’s first gasoline-powered engine built on the B-platform. It delivers diesel-like performance with up to 300 hp and 660 lb-ft of torque, offering an alternative fuel option for medium-duty fleets.
What about applications that need more power than a 6.7L can provide?
Cummins L9: The Mid-Range Powerhouse
The L9 is an 8.9L engine that bridges the gap between medium and heavy-duty applications. With over 35 years of production history and 5 million units built, it has a proven track record.
L9 Key Specifications:
| Specification | Detail |
|---|---|
| Displacement | 8.9L |
| Horsepower | 260-380 hp |
| Torque | 860-1,250 lb-ft |
| Governed Speed | 2,100/2,200 rpm |
| Dry Weight | 1,695 lbs |
L9 Power Ratings:
- Performance Ratings: 370-380 hp with 1,250 lb-ft torque
- Productivity Ratings: 260-360 hp with 860-1,150 lb-ft torque
The L9 features replaceable cylinder liners for easier rebuilding, adding to its residual value. It’s available with both front and rear PTO options for vocational applications. The L9 uses a Cummins VGT Variable Geometry Turbocharger to deliver higher torque and lower emissions.
For the heaviest loads and longest hauls, you need something bigger.
Cummins X15: The Heavy-Duty Legend
The X15 is Cummins’ flagship heavy-duty engine. With a 14.9L displacement, it delivers the power and torque needed for the most demanding linehaul and vocational applications.
X15 Key Specifications:
| Specification | Detail |
|---|---|
| Displacement | 14.9L |
| Horsepower | 400-500 hp (Efficiency Series) up to 675 hp (Performance Series) |
| Torque | 1,450-1,850 lb-ft (Efficiency Series) up to 2,050 lb-ft (Performance Series) |
| Governed Speed | 1,700 RPM |
| Dry Weight | 2,961 lbs |
X15 Rating Options:
Efficiency Series (for fuel economy):
- 400-500 hp with 1,450-1,850 lb-ft torque
- SmartTorque (ST) ratings provide additional torque in top 2 gears
- EX ratings use GPS data for dynamic powertrain optimization
Performance Series (for maximum power):
- 450-675 hp with up to 2,050 lb-ft torque
- Available for on-highway and vocational applications
The X15 uses a high-pressure fuel injection system and VGT turbocharger for exceptional throttle response. It’s available with a powerful engine brake for improved retarding force. For European markets, the X15 is available in EGR-free versions to meet Euro VI standards.
Head-to-Head Comparison: Choosing the Right Engine
| Feature | S13 Integrated | Cummins B6.7 | Cummins L9 | Cummins X15 |
|---|---|---|---|---|
| Displacement | 12.7L | 6.7L | 8.9L | 14.9L |
| Horsepower Range | Up to 515 hp | 200-300 hp | 260-380 hp | 400-675 hp |
| Torque Range | Up to 1,850 lb-ft | 600-660 lb-ft | 860-1,250 lb-ft | 1,450-2,050 lb-ft |
| Best For | Linehaul, regional, vocational | Medium-duty delivery, municipal | Vocational, refuse, school bus | Heavy linehaul, heavy haul |
| Key Tech | No EGR, dual-stage SCR, integrated T14 trans | High-pressure common rail | VGT turbo, replaceable liners | SmartTorque, VGT turbo |
| EPA 2027 Ready | Yes, 90% parts carryover | Yes (B6.7 Octane) | EPA 2024 certified | EPA 2024 certified |
| Weight (Dry) | 2,284 lbs | 1,301 lbs | 1,695 lbs | 2,961 lbs |
Which Engine Is Right for Your Fleet?
Choose the S13 Integrated If:
✅ You want industry-leading fuel economy—the LT with S13 leads the on-highway aero category by at least 5%
✅ You value an integrated powertrain designed to work as a system
✅ You want to eliminate EGR complexity and reduce regen downtime
✅ You’re planning for EPA 2027 compliance without major changes
✅ You need up to 515 hp for linehaul or vocational work
Choose Cummins B6.7 If:
✅ You operate medium-duty trucks for delivery or municipal service
✅ You value the proven reliability of the B-platform
✅ You’re interested in the new gasoline-powered Octane option
Choose Cummins L9 If:
✅ You need more power than the B6.7 in a mid-range package
✅ You operate vocational trucks requiring PTO capabilities
✅ You want the ability to rebuild with replaceable cylinder liners
Choose Cummins X15 If:
✅ You need maximum power for heavy haul applications
✅ You operate in demanding terrain requiring up to 675 hp
✅ You prefer the SmartTorque feature for optimized gear retention
The Future: EPA 2027 and Beyond
The S13 Integrated Powertrain was engineered with a long-term vision. When the EPA’s 2027 regulations take effect (reducing NOx limits from 0.20 to 0.035 g/bhp-hr), the S13 will require only minimal changes.
2027 S13 Updates:
- Variable Valve Timing (VVT): Adapts valve timing for smooth performance and exceptional power across all conditions
- 24V Electrical Architecture: Improved cold-crank performance, 40% weight savings in components
- 24V Transmission Control Module: Uses GPS and topography data for predictive shifting
- Closed Crankcase Breather and Oil Centrifuge: Additional emissions and maintenance improvements
Best of all, 90% of components carry over unchanged, meaning your service tools, parts, and technician training remain familiar. The S13 is also approved for use with R100 renewable diesel, reducing well-to-wheel carbon footprint without hardware changes.
Frequently Asked Questions
What is the International S13 Integrated Powertrain?
The S13 is International’s proprietary 12.7L engine paired with the T14 14-speed transmission and dual-stage aftertreatment, designed together as a complete system for maximum efficiency and performance.
How does the S13 differ from Cummins engines?
The S13 uses an SCR-only emissions strategy with no EGR cooler, while Cummins engines typically use a combination of EGR and SCR. The S13 is also fully integrated with its dedicated T14 transmission.
What is the B6.7 Octane?
The B6.7 Octane is Cummins’ first gasoline-powered medium-duty engine, built on the proven B6.7 platform, offering up to 300 hp and 660 lb-ft of torque.
Which engine is best for vocational applications?
The S13 offers specialized vocational drive modes including paver, off-road, and split shaft modes, while the L9 and X15 are also proven vocational performers. The L9’s replaceable cylinder liners add rebuild value for demanding service.
Is the S13 EPA 2027 compliant?
Yes. The 2027 S13 Integrated Powertrain meets EPA’s stricter NOx regulations with 90% parts commonality to the current platform, requiring minimal updates.
What is the fuel economy advantage of the S13?
The International LT with the S13 Integrated Powertrain leads the on-highway aero category by at least 5% compared to competitive models.
Can the S13 run on renewable fuels?
Yes. The S13 is approved for use with R100 renewable diesel without any hardware changes.
References
Explore Official International and Cummins Resources:
- International S13 Integrated Powertrain Official Page
- Cummins B6.7 Octane
- Cummins L9 (2024)
- Cummins X15 Efficiency Series
What’s your experience with International and Cummins powertrains? Share your questions and stories in the comments below.
