The all-new S13 Integrated Powertrain is Navistar's latest innovation, designed to be one of the last ground-up internal combustion powertrains developed. This impressive 12.7-liter diesel engine is engineered for peak efficiency, ruggedness, and power, aiming to surpass its predecessor, the A26 Diesel. Experience the future of heavy-duty trucking with the S13, a testament to cutting-edge engineering.

The S13 aims to overthrow Navistar’s previous flagship, the A26 Diesel, introduced five years ago. This 400-horsepower, 2,284-pound diesel will achieve significantly better fuel economy than its older sister. The engine has been carefully developed by a conglomerate of engineering luminaries to be as easily serviced and repaired as possible. It features a low-pressure oil pump, double overhead cams, a fixed geometry turbocharger, and a 23:1 compression ratio – all contributing to its impressive efficiency.

Explaining the virtues of the S13, Navistar’s Michael Grahe noted that the truck is designed for long service life. The self-shifting T14 transmission system seems, by all accounts, to be more than capable of delivering the trinity of quiet, smooth, durable performance. Whether you opt for the sleeper-cab or regular-cab version, the S13’s T14 transmission features dual creeper gears with close ratios running up to 13th gear in direct drive and tipping into overdrive in 14th gear. 14th-overdrive is programmed to kick in when the truck is headed downhill or carrying a light load, but fuel economy is typically best when the truck is loaded and running in 13th-direct gear. To keep things running smoothly under all conditions, you’ll have an additional 469 retarding horsepower thanks to the compression engine brake that comes as standard with the truck.

If you’re focused on reducing your carbon footprint and helping keep the environment clean, you’ll appreciate the S13. It comes equipped with an advanced aftertreatment system that uses a two-stage diesel exhaust fluid (DEF) dosing setup. The first stage is positioned near the turbocharger, while the second stage occurs in the enclosure that also houses the diesel particulate filter. The S13 does not require active regenerations for effective operation, but it retains the capability to initiate them when needed. This is a significant step forward from previous generations of trucks and long-distance haulers.

The S13 diesel is in high demand, as illustrated by the range of configurations in which it will be rolled out. Expect ratings ranging from the 370-horsepower, 1,250 lb-ft torque models to the 515-horsepower, 1,850 lb-ft iteration. The highest fuel economy will likely be seen in the 400-horsepower version, which might see up to a 15% efficiency improvement.

Navistar is pinning much hope on the S13’s global performance, so they have conducted extensive testing in extreme climates. It has been taken through 4 million miles of terrain ranging from Alaska to Arizona and has successfully undergone more than 400,000 road hours of dynamometer testing. According to Navistar Director David Hillman, Navistar intends for this to be its best—and possibly last—internal combustion engine and transmission, built at its newly expanded factory in Huntsville, Alabama.