When International’s engineering team joined forces with MAN and Scania back in 2017 to design a new heavy-duty powertrain from scratch, they started with a radical design philosophy: forget about emissions — for now.
As Keith Watts, International’s training specialist, put it during a comment before my test drive, “Let an engine be an engine.”
Stepping back a bit, design work on the S13 began shortly after Volkswagen Truck & Bus (now Traton Group) acquired a 16.6% stake in Navistar (now International Motors). This brought together engineering teams from Traton subsidiary, Scania and International, beginning a five-year, multi-billion-dollar effort that produced what North Americans know as S13 Integrated powertrain.
The exact same powertrain, dubbed Scania Super, entered European service in 2021. Earlier this year, it went into production with another Traton Group subsidiary, MAN. They call it the D30. It was formally revealed to North America in August of 2022.
Trucknews.com finally got ride in one this past summer during a Customer Experience Tour stop at Altruck International Truck Centres in Burlington, Ont.
It’s a global platform sharing about 85% parts and design commonality. The remaining 15% are largely variations necessary to accommodate the difference between cabover and conventional trucks. The engines are nearly identical, as is the 14-speed transmission and the aftertreatment system.
Scania pioneered the all-SCR, no-EGR emissions strategy with its DC13 engine in 2014 to meet Euro VI emissions standards. It continues to evolve to meet ever more stringent emissions standards.
“The low-carbon, high-NOx design concept hinged on having the engine just create power and produce NOx as a byproduct,” recalled Jonathan Hutchison, Sr., powertrain launch manager at International. “The idea was, let the engine generate power and heat to burn off particulate matter, and let the aftertreatment system take care of all the NOx.”
S13 goes away with EGR
At the heart of the engine is a 23:1 compression ratio — unusually high by modern diesel standards — to produce hotter combustion and a near soot-free burn.
The engine does not use cooled exhaust gas recirculation to mute the efficiency of the burn in order to reduce NOx. This increases soot production and fouls the diesel particulate filter.
To handle the higher-than-usual NOx load resulting from hotter combustion, the S13 uses a dual-dosing SCR system that injects diesel exhaust fluid (DEF) at two points in the exhaust stream. The first dose occurs close to the turbo outlet, and the second downstream in the one-box aftertreatment unit. This staggered approach allows more precise NOx reduction under a wide range of temperatures and loads.
“We do dose twice with DEF, but we aren’t dosing twice the amount,” Hutchison told trucknews.com. “Our dosage percentage is higher than industry average, roughly about 6-8% while others are in the 5.5-6% range.”
While DEF consumption is slightly higher, the tradeoff is the elimination of the diesel oxidation catalyst (DOC) and the so-called seventh injector to perform active regens.
Real-world testing backs that up. Trucks equipped with the S13 have gone more than a year-and-a-half without a single active regeneration event.
“The forced-regen button will be the dustiest button on the dashboard,” Hutchinson quipped.
International claims that when fuel economy averages above 8.2 mpg, the DPF can last up to 650,000 miles (1,040,000 km) before replacement. That’s often into the second ownership cycle.
While the troublesome EGR cooler is gone, the S13 still has an EGR system, but for an entirely different purpose. Combined with variable valve timing, the EGR is used during periods of coasting or idling and at cold startup to keep the aftertreatment system hot and functioning most efficiently.
The transmission ties it together
The T14 14-speed transmission is the other half of the integrated design — developed specifically for the S13 and not sold separately.
It’s a compact, fully automated manual with evenly spaced 29% gear steps that keep power delivery smooth across the range.
Instead of the industry-standard air-actuated clutch, the S13 uses an electronic clutch actuator (ECA) — a self-adjusting linear unit that can engage the clutch as smoothly or aggressively as needed. The result is seamless shifting, minimal driveline shock, and reduced wear over time.
A clever planetary gear set built into the tail housing provides two reverse speeds for highway trucks and up to six for vocational models, with ultra-deep first gears as low as 20:1.
The transmission’s pressurized lubrication and temperature-conditioning system circulates oil through a liquid-to-liquid cooler. That not only reduces drag losses, but also extends filter and oil life to about 600,000 miles (960,000 km) — another nod to uptime.
Versatile PTO and chassis integration
Both front- and rear-mounted PTOs are available for vocational applications, with options for one or two rear units. Every chassis is pre-wired for PTO installation, meaning fleets can add equipment later without cutting into the harness.
When ordered from the factory, the PTO carries the same warranty as the transmission. Control logic is integrated through Diamond Logic, International’s electrical architecture, for programmable parameters and safe operation.
The finer points
International claims the S13 is the lightest 13-liter engine on the market today, tipping the scales at 2,284 lb. (1,038 kg), according to published figures. Comparing published data from other manufacturers shows the S13 is about 300 lb. (136 kg) lighter than its closed rival, and nearly 800 lb. (364 kg) lighter than the heaviest engine in class.
Remember, weight is subject to how the manufacturer presents the engine, with or without oil and/or a flywheel, including the aftertreatment or not. It’s hard to make direct comparisons.
Fuel efficiency is often almost as difficult to surmise, but Navtej Singh, International’s director of engineering, is pretty sure of his claims.
“We are already fuel economy leaders in Europe*,” he insists. “Now we have A-B testing that shows with the same hardware set, same rear axle ratios, etc. on the Indiana and Kentucky fuel economy test cycles, we are 6.5% or higher more fuel efficient than our competitors.”
*In 2023, the Scania Super won the European Truck Challenge for fuel efficiency showing 4.9% better than the nearest competitor. That event takes place on public highways in real-world driving conditions around Hanover, Germany.
There’s no disputing the drivability of this powertrain. The evenly spaced gear steps coupled with peak torque delivered from 900 rpm all the way out to 1,400 rpm ensures there is plenty of pull available in any gear when the engine is at its most fuel efficient.
Also, and this is no small matter, the powertrain is expected to meet EPA27 emission standards with minimal modifications.
“We set up this powertrain in such a way that when we go from 2024 to 2027, we don’t have to make major changes,” Singh said. “We don’t want to surprise our customers, so we laid the foundation for 2027 when we launched this powertrain.”
Driving the S13
Since the 2006 introduction of the ProStar, I’ve driven other ProStars, LoneStars and LTs with Cummins, MaxxForce, and A26 engines — seven test drives of International product.
I’ve seen good and bad from the truck maker, and I have a bit of a feel for the product. I can say, with no reservation, this LT/S13 combination is top of the heap. It’s a great driving truck.
From Altruck International’s lot on the QEW’s south service road in Burlington, we bobtailed down to a lakeside park in downtown Burlington for a few photos, and then made our way over to Hwy. 6 and Clappison’s Cut, the traffic-choked grade heading north off the Queen Elizabeth Way near Hamilton. We ran north for about 15 minutes, then turned around just south of Morriston, near the junction with Hwy. 401.
Between the stop-and-go in urban Burlington, the 20 or so miles (32 km) at highway speed on the QEW and the miles on Hwy. 6, I got a pretty good feel for the truck.
Maneuvering Mode
One feature I really liked was Maneuvering Mode. This is something unique to the S13, as far as I know. In the lower gears at launch, the electro-mechanical clutch actuator will engage the transmission as you take your foot off the brake pedal. This is called Creep Mode. It behaves like an automatic transmission, where the torque converter urges the vehicle to move.
With Maneuvering Mode engaged (there’s a button on the B-panel with a cute little turtle icon), Creep Mode is disengaged.
The truck won’t roll when the brakes are released. Also, this “desensitizes” the throttle pedal, giving you more movement of the pedal per increase in rpm. This allows for more precise speed control at low speed — such as when hooking up to a trailer, backing into a dock, or driving bobtail. It disengages automatically above 9 mph (14 km/h).
Skip the shifting
Also deserving of mention here is the super-smooth shifting T14 transmission. You won’t use the lowest gears often under normal U.S. weight loads, but it’s nice to have them. Final drive (14th) is 0.78 overdrive. Direct is 13th gear.
The clutch actuators are electro-mechanical, rather than pneumatically driven. That means they can be very precisely controlled. The result is gear changes you hardly even notice.
The traffic on Hwy. 6 is trying at the best of times, but true to form, it provided several opportunities to test the adaptive cruise control and collision mitigation systems. I was impressed with how they performed, and I don’t say that often.
This may come as disappointing to some, but there’s nothing flashy or fancy about this truck and its powertrain. It’s just very competent. It’s comfortable and quiet, and while drivers will probably never even notice all the engineering that went into this, fleets certainly will.
They see it in terms of better fuel efficiency and lower maintenance costs owing to the lack of a cooled EGR loop and the incessant regens common with other engines. Advanced telematics will deliver better diagnostic data and vehicle condition reports, which can turn breakdowns into planned service events.
International was bitten once before after tinkering with emissions systems. One has to believe it won’t let that happen again. The powertrain has been in service for several years now, here and overseas, and disparaging online posts about maintenance and reliability are few and far between.
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