Truck & Off-Highway Engineering - December 2021 - 7

TECHNICAL INNOVATIONS
POWERTRAIN
Navistar updates A26 engine, improves FE by 4%
The 2021 GHG-compliant
International A26 engine
features an increased compression
ratio, from 18.5:1 to 20.5:1, and a variable
water pump that provides more optimized run time.
Since the initial launch of the International A26 engine five years
ago for the Class 8 market, Navistar engineers have tweaked the
power plant to improve fuel economy (FE) by 10%. Previous design
and system updates account for a 6% FE improvement, while
the latest significant enhancements to the 2021 Greenhouse Gas
(GHG) A26 engine provide an additional 4% 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, " said Diane
Hames, VP of Marketing. " 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 engine design and system updates include combustion
enhancements and optimized engine temperature
control. An increased compression ratio, from 18.5:1 to 20.5:1,
The updated A26 produces
up to 515 hp and 1,850 lb.-ft.,
compared to 475 hp and 1,750 lb.-ft.
for the previous version.
delivers higher combustion efficiency along with maximized
fuel injection pressure from the 2,500-bar (36,260-psi), highpressure
common-rail fuel system. Efficient design of the cylinder-head
coolant passages helps to reduce parasitic loss at
the water pump. The addition of a variable water pump provides
more optimized run time versus constant " on. "
Air management system updates feature an optimized exhaust
gas recirculation (EGR) cooler and intake throttle valve
that create more efficient charge air flow. The variable geometry
turbocharger delivers the desired boost air pressure
across a wide range of engine speeds, loads and elevation.
At 2,314 lb (1,050 kg), the latest-generation A26 is the lightest
engine in its class, Navistar claims. The 13-L engine reportedly
weighs 600-700 lb (272-318 kg) less than typical 15-L
big-bore engines. Higher power output while operating at
lower rpm optimizes the amount of fuel consumed during
operation. Built from the proven MAN D26 engine crankcase,
the latest version of the A26 produces up to 515 hp (384 kW)
and 1,850 lb.-ft. (2,508 Nm), compared to 475 hp (354 kW)
and 1,750 lb.-ft. (2,373 Nm) for the previous version.
" The updated International A26 provides the horsepower
you'd expect from a 15-L engine, while working harder at lower
engine speeds, " said Chet Ciesielski, VP of 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 new-generation A26, which was on display during the
The new-generation A26 engine powers Class 8 trucks such as the
International RH Series of regional haul vehicles.
TRUCK & OFF-HIGHWAY ENGINEERING
recent American Trucking Associations' Management
Conference and Exhibition in Nashville, Tenn., is available for
order in the International LT Series of long-haul vehicles, RH
Series of regional haul vehicles, the HX Series for heavy-haul
and various construction applications and the HV Series for
select vocational applications.
Ryan Gehm
December 2021 7
ALL IMAGES: NAVISTAR

Truck & Off-Highway Engineering - December 2021

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - December 2021

Truck & Off-Highway Engineering - December 2021 - CVR4
Truck & Off-Highway Engineering - December 2021 - CVRA
Truck & Off-Highway Engineering - December 2021 - CVRB
Truck & Off-Highway Engineering - December 2021 - CVR1
Truck & Off-Highway Engineering - December 2021 - CVR2
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Truck & Off-Highway Engineering - December 2021 - CVR3
Truck & Off-Highway Engineering - December 2021 - CVR4
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