Navistar A26 Engine
Oday Forster
The S13 Integrated Powertrain offers customers several benefits contributing to higher operational efficiency and improved performance. In comparison to the first-generation International A26 engine specified with the 12-speed overdrive Eaton Endurant HD automated transmission, the S13 Integrated Powertrain is the lightest weight powertrain on the market, providing a weight reduction of 52 lb. With the same comparison when specified with the updated International LT Series aerodynamics package, the S13 Integrated offers up to a 15% gain in fuel efficiency*.
The S13 engine operates on low revolutions and higher torque equating to fewer fuel injections and less fuel consumption. Designed with selective catalytic reduction (SCR) technology as the primary emissions reduction technology in mind, the S13 engine has no exhaust gas recirculation (EGR) cooler and flows 100% of the exhaust to the turbocharger in normal engine operating conditions. This process delivers more power and improved engine performance. Eliminating the recirculation of exhaust gas ensures a more complete fuel burn and allows cleaner air to enter the combustion chamber on the intake cycle to mitigate soot buildup.
With the goal of improving uptime through elimination of subcomponents, the S13 engine has succeeded in improving efficiencies in multiple areas. A fixed geometry turbocharger reduces system complexity and increases reliability. Low friction materials and finishes are used for the liners, rings and bearings. The design eliminated the downstream fuel injector and the high-pressure fuel pump operates at a lower pressure of 1,800 bar. Additional features include a dual overhead cam design and cast aluminum cam cover and oil pan, 23:1 compression ratio and a compression release brake for maximum engine braking power. The compacted graphite iron block of the S13 engine combined with a cast aluminum cam cover and oil pan help make this the lightest weight 13L powertrain available in North America.
The first commercial transmission offered by International, the International T14 is a 14-speed fully automated manual transmission with an electronic clutch actuator to deliver faster, smoother shifting.
The T14 features a planetary gear set that supports a compact design and optional programmable reverse speeds. This transmission has two crawler gears for improved heavy load startability and low-speed maneuvering. Complete with deep low-end gearing and shifting smoothness, the T14 delivers efficiencies of a direct drive in an overdrive package.
The S13 Integrated Powertrain offers increased power, with the full torque available at 900 RPM to support drivability. Drivers have shift-on-the-fly capabilities with Economy, Performance and Performance+ modes. Also included are intelligent shifting capabilities, like skip shifting and turning radius offsets.
Since an EGR cooler was eliminated from the combustion process, less soot and particulate matter are generated. This cleaner combustion cycle allows for extended service intervals and eliminates the need for active regeneration cycle and the diesel oxidation catalyst. By employing a design which eliminates the need for active diesel particulate filter regeneration, the Dual Stage Aftertreatment system saves fleets time and fuel.
The International S13 Integrated Powertrain includes several customer benefits outside of the product itself, including dealer integrated software, built-in service products, repair maintenance contracts and other solutions available for International vehicles equipped with the new S13 Integrated Powertrain.
*Comparing the fuel economy of the 2017 GHG International A26 engine in a 2021 model year International LT Series truck with aero package to the fuel economy of the new International S13 Integrated Powertrain in a 2024 model year International LT Series truck with the LT aero package and chassis enablers. Actual customer results may vary due to various factors, including but not limited to truck specifications, weight of the vehicle, predictive features, environmental conditions, etc.
From city streets to open roads, work sites to delivery routes. The demands of your profession require the best diesel engines available to ensure vehicles and fleets always operate at the highest level.
LISLE, Ill., Oct. 20, 2021 /PRNewswire/ -- Navistar today announced significant updates to the International A26 engine, now allowing fleets to achieve 10% improved fuel economy since the engine's initial launch.
"These latest updates to the International A26 highlight Navistar's ongoing commitment to improved vehicle efficiency and total cost of ownership for our customers," said Diane Hames, vice president, Marketing. "Our key drive continues to be meeting the demands of our customers today while helping them plan for the road ahead. Every incremental change helps to forge a path toward that more efficient future."
The previous updates contributing to the 6% fuel efficiency improvement include more optimized engine and transmission calibrations mated with the Eaton Endurant automated manual transmission, a direct drive 2.15 ratio, and aerodynamic improvements to wheel coverings on drive axle wheels and the chassis.
The latest generation International A26 13-liter engine was designed to provide greater fuel efficiency without sacrificing power. Built from the proven MAN D26 engine crankcase, this latest version of the International A26 produces up to 515 horsepower and 1,850 lb.-ft. of torque.
"The updated International A26 provides the horsepower you'd expect from a 15L engine, while working harder at lower engine speeds," said Chet Ciesielski, vice president, On-Highway Truck Business. "The active torque management at the pedal delivers the required amount of torque at the moment it's needed while providing a smoother shifting experience for the driver."
About Navistar
Navistar, Inc. ("Navistar") is a purpose-driven company, reimagining how to deliver what matters to create more cohesive relationships, build higher-performing teams and find solutions where others don't. Based in Lisle, Illinois, Navistar or its subsidiaries and affiliates produce International brand commercial trucks and engines, IC Bus brand school and commercial buses, all-makes OnCommand Connection advanced connectivity services, and Fleetrite, ReNEWeD and Diamond Advantage brand aftermarket parts and includes a Brazilian manufacturer of engines and gensets, MWM Motores Diesel e Geradores. With a history of innovation dating back to 1831, Navistar has more than 12,000 employees worldwide and is part of TRATON SE, a global champion of the truck and transport services industry. Additional information is available at www.Navistar.com.
The Navistar DT (Diesel Turbocharged or Diesel Turbo) engine family is a line of mid-range inline-6 diesel engines. With horsepower ratings ranging from 170 hp (130 kW) to 350 hp (260 kW), the Navistar DT engines are used primarily in medium-duty truck and bus applications such as school buses, although some versions have been developed for heavy-duty regional-haul and severe-service applications.Prior to 1986, Navistar International, then known as International Harvester Company, used the DT engine in farm and construction equipment.
The Navistar DT diesel engines are of a wet-sleeve design. This means that the cylinder wall (sleeve) is a separately machined part that fits into the cylinder bores cast into the engine block. The cylinder sleeve is in contact with the engine coolant, hence the "wet"-sleeve.
Navistar claims that the wet-sleeve design enhances durability because the consistent wall thickness of the sleeve allows for consistent heat transfer, ensuring the cylinders stay round during thermal expansion. Additionally, they state that the hardened cylinder sleeve is more durable and wear resistant than a softer, cast-in wall. Also, the replaceable cylinder sleeves protect the block from damage (e.g. in case of foreign objects entering the cylinder) and can easily be replaced, which Navistar claims enables simpler restoration to original specifications. The wet-sleeve design also allows the engine to be rebuilt easily to factory specifications, sometimes without even removing the engine from the vehicle.
This design is opposed to parent bore engines, where the cylinder walls are machined out of the bores cast into the block. International states that the uneven thickness of the cylinder walls causes the cylinders to become out of round during thermal expansion, increasing wear. Also, damage to the cylinder wall requires more extensive work to repair.
From 1984 until late 1995, the DT engines used a Bosch pump-line-nozzle (PLN) mechanical direct fuel injection system. 1984 through 1992 DTs used a Bosch MW style pump, while the 1993-1995s used a Bosch P style pump, and starting what was called New Generation Diesel engine design, which is still the same basic block design. Mechanical injection was still utilized in trucks up into the 1997 year, but this is rare. In 1994, due to tightening emissions regulations, the engines were redesigned to use electronically controlled unit direct fuel injection. From 1994 to 2004, the engines used HEUI (Hydraulically actuated Electronically controlled Unit Injection) injectors, co-developed by Navistar and Caterpillar Inc.[4] From 2004 to 2009, the engines use International's Electro-Hydraulic Generation Two (G2) unit injectors.
From the time the United States Environmental Protection Agency's 2007 emissions regulations went into effect, the Navistar DT engines were available in three configurations in what turned out to be their final generation prior to discontinuation. These variants were renamed to conform to International's then-new MaxxForce engine brand.
The engines were also available for defense applications under the MaxxForce D brand. The final generation MaxxForce DT was known as the MaxxForce D7.6I6, and the MaxxForce 10 was known as the MaxxForce D9.3I6. Modifications from the civilian versions included diamond-coated (metal nitride coating) injectors[citation needed] to enable the engines to run on JP-8 fuel.[8]
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