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International A26 Engine Updates Further Improve Efficiency and Performance


The International® A26 engine

Navistar announced updates to the International® A26 engine, allowing fleets to achieve 10% improved fuel economy since the engine’s launch.

Previous design and system updates account for a 6% fuel efficiency improvement; the latest engine enhancements to the A26 (2021 GHG) provide an additional 4% fuel economy benefit.

“These latest updates to the International A26 highlight Navistar’s ongoing commitment to improved vehicle efficiency and total cost of ownership for our customers,” says 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.”

Previous updates contributing to the 6% fuel efficiency include more optimized engine and transmission calibrations with the Eaton Endurant transmission. Other contributions include aerodynamic improvements to wheel coverings on drive axle wheels and the chassis.


The latest engine enhancements to the A26 (2021 GHG) providing an additional 4% fuel economy benefit include:

  • Combustion enhancements. An increased compression ratio from 18.5:1 to 20.5:1. This delivers higher combustion efficiency with maximized fuel injection pressure from the 2500 bar high pressure common rail fuel system.
  • Optimized engine temperature control. The efficient design of the cylinder head coolant passages helps reduce parasitic loss at the water pump. The addition of a variable water pump also provides more optimized run time versus constant “on.”​
  • Air management system updates. An optimized exhaust gas recirculation (EGR) cooler and intake throttle valve create more efficient charge air flow. Additionally, the Variable Geometry Turbocharger delivers the desired boost air pressure across a range of engine speeds, loads, and elevation.
  • Reduced engine speed without compromising power. A higher horsepower output provides maximum power when needed; operating at lower rotations per minute (rpm) optimizes the amount of fuel consumed during operation.

Navistar designed the latest generation A26 13-L engine to provide greater fuel efficiency without sacrificing power. Built from the MAN D26 engine crankcase, this A26 version produces up to 515 hp and 1,850 lb-ft of torque.

“The updated International A26 provides the horsepower you’d expect from a 15-L engine, while working harder at lower engine speeds,” says 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.”

The A26 engine is available for order in the International® LT® Series as well as the RH™ Series. It’s also available in the HX® Series for heavy-haul and construction applications and the HV™ Series for vocational applications.

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