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The International® S13® Integrated Powertrain isn’t your momma’s Navistar engine. Since its unveiling last year, the S13 has taken the commercial trucking industry by storm.
Born from a clean sheet design through global collaboration between Navistar and the TRATON GROUP, the S13 Integrated Powertrain integrates the 12.74L S13 Engine, 14-speed automated manual T14 Transmission and Dual Stage Aftertreatment to provide maximum performance and the most efficient, reliable and sustainable powertrain Navistar has ever produced. Available for International LT® Series, RH™ Series and HX620 models, the S13 has a lot to offer for companies looking to streamline the overall operation of their fleets. To help International truck owners shift their idea of what’s possible for their business, we broke down the advantages the S13 Integrated Powertrain provides.
1. Smooth Operation and Superior Performance
The “clean sheet” S13 Integrated Powertrain was designed from the ground up without starting from the A26, N13 or other previous International engines. Its three distinct components — engine, transmission and aftertreatment system — were all developed concurrently to ensure maximized compatibility and integration between systems, leading to a smoother and quieter driving experience while improving upon the performance International drivers have come to expect.
The S13 Engine has seven engine rating options and delivers up to 515 hp and 1,850 lb.-ft. of torque at 2,000 revolutions per minute (RPM). Even the most efficient engine rating, code 12BGT, achieves 400 hp, and full torque is available at only 900 RPM. The engine compression ratio was also improved to 23:1 compared to the 20.5:1 ratio offered by the International A26 engine, equating to more power and better fuel economy.
The S13 Integrated Powertrain also features a wide gear ratio that provides optimal efficiency and performance on both flat roads and hilly terrain. And the new compression release brake ensures secure braking power up to 470 hp when descending, operating at approximately 300 RPM higher than the A26 brake.
Perhaps one of the biggest performance boosters for the S13 Integrated Powertrain is the elimination of the exhaust gas recirculation (EGR) cooler and variable-geometry turbocharger (VGT). In a typical engine, the EGR cooler recirculates about 20% of the gas out of the exhaust flow and into the front of the engine, meaning only 80% of produced energy goes to the turbocharger. The absence of the EGR cooler in the S13 allows nearly 100% of energy to flow to the simpler, more reliable fixed-geometry turbocharger (FGT), ensuring a more complete fuel burn and delivering more power and improved engine performance.
2. Reduced Weight
The introduction of the new dual stage aftertreatment in the S13 Integrated Powertrain allowed for the removal of the heavy EGR cooler, eliminating 40-50 lbs. from the overall weight of the unit. In addition, the T14 Transmission’s planetary gear set eliminates the need for a dedicated reverse gear, allowing for a lightweight, efficiently packaged gearbox. And the single countershaft with helical gears provides overall weight savings without compromising the durability or performance of the transmission.
All of this allows the S13 to be the lightest 13-liter diesel engine on the market, offering a 52-lb. weight reduction compared to the A26 engine*. This weight reduction allows LT Series, RH Series and HX620 trucks to achieve remarkable payload capacities and improved fuel economy.
3. Increased Fuel Efficiency
Speaking of fuel economy, the S13 Integrated Powertrain provides up to a 15% increase in fuel efficiency compared to the first-generation A26 engine**. To put this into perspective, if a truck equipped with the S13 was driven 100,000 miles in one year, you would save 1,650 gallons of fuel or $6,930 (assuming a price of $4.20/gallon). The improvements in fuel efficiency and reductions in fuel consumption are the result of many design improvements made by S13 engineers:
- The S13 Engine operates at low RPMs and high torque, resulting in fewer fuel injections and less fuel consumed.
- A new cylinder and piston head with maximum cooling properties were designed along with a new double overhead camshaft (DOHC) featuring an integrated compression release brake assembly and parallel valve pattern. Combined, these result in reduced parasitic losses.
- The engine was converted from a 10-blade to a 6-blade fan to increase efficiency.
- A higher compression ratio, higher air-to-fuel ratio, new peak cylinder pressure of 250 bars, longer fuel burn duration, XPI injectors that operate at lower pressures and adapt for the quick release of fuel, and reversing the rotational direction of the turbine wheel all contribute to improved combustion efficiency.
- Friction within the powertrain was reduced by improving the materials used on liners, rings, coatings and bearings as well as using a single countershaft geartrain design for the T14 Transmission rather than a dual countershaft.
- The high-pressure fuel pump was designed to operate at only 1,800 bars of pressure compared to the 2,500 bars needed to operate the fuel pump in the A26, a 28% decrease that means less energy is needed to pressurize the fuel and lower parasitic losses.
- Pumping losses were further improved by optimizing the size and flow rate of the coolant pump, ensuring efficient air passage through the intake and exhaust manifolds, and using a DOHC with separate intake and exhaust cams.
4. 14-Speed Overdrive Transmission with Shift-On-The-Fly Capabilities
The T14 is a 14-speed, fully automated manual transmission and International’s first commercial transmission to go to market. Thanks to the holistic design behind the S13 Integrated Powertrain, the transmission’s electronic clutch actuator works in sync with the S13 Engine, resulting in gear shifting that is perfectly matched to engine revolutions for a faster, smoother shifting experience. Drivers also get the benefit of a quicker-accelerating package in a downsped configuration thanks to the T14 Transmission’s overdrive 14th gear and direct drive 13th gear optimized to deliver peak fuel economy during typical load.
The T14 was designed to not consume air during complicated maneuvers, such as backing a truck into tight spaces, which means drivers do not need to stop and let air recharge. And the transmission also uses an integrated oil-to-water coolant system that optimizes temperature regulation in hot and cold environments, allowing the T14 to achieve an unlimited Gross Combination Weight Rating (GCWR) for on-highway applications.
Two crawler gears on the transmission offer heavy-load stability and low-speed maneuvering capabilities as well as consistent performance when carrying heavy loads requiring lower rear axle ratios. Plus, Eco, Performance and Performance+ modes allow drivers to shift on the fly, and options for downhill speed control, eco-coast and creep modes enhance driving performance even further.
5. Easily Serviced and Sustainable Dual Stage Aftertreatment
According to Navistar, the S13 Engine will be the last internal combustion engine it will ever produce as it shifts its focus to investing in and developing carbon-neutral technologies. However, until electric, zero-emissions vehicles are widely available, the S13 Integrated Powertrain is EPA-compliant and designed to be as sustainable as possible. And we have the new Dual Stage Aftertreatment system to thank for it.
Difficulties with heavy-duty emission-control systems such as clogged diesel particulate filters (DPFs), EGR failures and sensor malfunctions cost fleet managers time and money. The Dual Stage Aftertreatment was developed alongside the selective catalytic reduction (SCR)-based S13 Engine to solve these problems through reduced complexity, increased serviceability and improved emissions control.
The removal of the EGR cooler from the S13 Engine combustion chamber means the EGR is primarily used for cold starts, not controlling emissions. It also means much less soot and particulate matter are generated since the engine can burn fuel more effectively. In fact, the reduction in soot buildup is so great it allows the powertrain to operate at lower temperatures, eliminating the need for a diesel oxidation catalyst (DOC) and active DPF regeneration cycles in the aftertreatment system. Instead, passive regeneration cleans out the DPF in most conditions.
However, as soot production is reduced, nitrogen oxide (NOx) emissions typically increase. To keep NOx emissions at bay, the Dual Stage Aftertreatment breaks down NOx using dual diesel exhaust fluid (DEF) injectors to distribute a first dose of DEF in the evaporator tube after exhaust flows through the turbocharger and a second dose in the aftertreatment container. As a result, the DPF only needs to be serviced every 650,000 miles.
All of this combined makes the Dual Stage Aftertreatment system a simple, reliable solution that’s easily serviceable when, and if, service is needed.
6. Power Take-Off (PTO) Options for Heavy-Duty Applications
Navistar announced in March 2023 that the S13 Integrated Powertrain will soon be available in International HX620 model trucks, expanding its capabilities from long haul and regional haul to vocational applications. The HX620 is ideal for severe-duty jobs in construction, dump, heavy haul and logging, meaning it needs a powertrain that can maintain speed and power, no matter the load.
To do just that, HX620 trucks equipped with the S13 Integrated Powertrain will come with the option of Rear Engine Power Take-Off (REPTO), Front Engine Power Take-Off (FEPTO) and single and dual output transmission PTOs. These PTOs will direct power produced by gear rotation in the transmission and transfer it to mounted equipment, such as a dump body, cement mixer or crane, to allow them to function. The optional PTOs will be installed on the S13 in the factory and carry the same warranty as the T14 Transmission.
To equip the S13 Integrated Powertrain even further for vocational applications, the T14 Transmission features vocational-specific drive modes such as off-road, manual and paver. Plus, the T14’s deep crawler gears provide slow-speed maneuverability and startability needed on job sites.
Inquire About the S13 Integrated Powertrain at Rush Truck Centers
Rush Truck Centers is excited to soon offer the new S13 Integrated Powertrain in International LT625, RH613 and HX620 trucks. Contact an International dealership near you or fill out our vehicle inquiry form to request more information or inquire about availability.
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*When paired with the 12-speed overdrive Eaton Endurance HD automated transmission.
**Comparing the 2017 GHG International A26 engine in a 2017 International LT with aero package to the new International S13 Integrated Powertrain in a 2024 International LT Series truck with the LT aero package and chassis enablers.
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