Truck & Off-Highway Engineering - December 2022 - 10

Navistar's 'ground up'
approach to all-new
DIESEL
ENGINE
Navistar claims that the S13 is the
lightest powertrain available in its size class.
The S13 Integrated Powertrain will be Navistar's final clean-sheet design of
a diesel ICE powertrain.
by Matt Wolfe
T
hough electrification has taken center stage for the commercial
trucking industry, diesel ICE powertrains will continue to
serve as the preferred propulsion system of many fleets for
decades to come. Navistar has committed to keeping the
diesel combustion engine relevant for the near future by revealing
the S13 Integrated Powertrain.
Truck & Off-Highway Engineering was on hand for the company's
reveal event in Las Vegas, where Navistar proclaimed that the S13 will
be its final clean-sheet design of a diesel ICE powertrain. The S13 is
intended specifically for the North American commercial-vehicle
market. It was developed over the past five years in a global collaboration
effort by the Traton Group, which encompasses Scania, MAN,
Volkswagen Truck & Bus, Navistar and RIO.
" The path toward a zero-emissions future requires improvements
to traditional propulsion technologies parallel to the development of
new powertrain technologies, " said Michael Grahe, executive vice
president of operations. " To ensure optimal reliability, efficiency, performance
and sustainability, we designed the S13 Integrated
Powertrain from the ground up. "
Grahe also discussed the extensive validation testing that Navistar
performed while developing the S13 powertrain. " Before this integrated
powertrain goes into serial production, this product will have
logged more than 4 million miles of field testing on North American
roads, " he said. " We are testing on all terrains - from the desert of
Arizona to the frozen tundra of Alaska. "
Navistar has not given a start date for the S13 to enter production
for the North American market (the engine already is in production in
Europe, where it is sold as the Super 13). When it does enter serial production
for North American customers, the S13 will be manufactured at
Navistar's Powertrain Manufacturing Plant in Huntsville, Alabama.
10 December 2022
A clean slate
The S13's clean-sheet design started with a modular
approach. Navistar's goal was to commonize many of
the S13's systems for mass customization across a
wide array of variants. This approach helps to ensure
the long-term viability of the S13's design should emissions
regulations for commercial diesel-powered ICE
vehicles become increasingly stringent. The engine,
transmission and aftertreatment system were designed
and developed concurrently to ensure maximized
compatibility and integration between systems.
Navistar claims that the S13 is the lightest powertrain
available in its size class thanks to a 52-lb
(23.5-kg) reduction in weight over the outgoing engine.
Total dry weight is listed at 2,284 lbs. (1,036 kg).
Other weight-saving measures include a cast aluminum
camshaft cover and oil pan as well as a compacted
graphite iron block.
The S13 also reportedly offers up to a 15% gain in
fuel efficiency when combined with the updated aerodynamics
package (see sidebar) that Navistar revealed
for the International LT Series. These gains were
achieved through greater combustion efficiency combined
with a reduction of friction and pumping losses.
Low-friction materials and finishes also were used for
the liners, rings and main bearings.
One of the guiding principles for the S13's operation
was to reach higher torque ratings at lower revolutions.
According to Navistar, operating the engine at
TRUCK & OFF-HIGHWAY ENGINEERING
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Truck & Off-Highway Engineering - December 2022

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