International Motors in 2022 unveiled its new in-house designed and engineered powertrain – the first new International on-highway product since regulators approved Volkswagen subsidiary Traton Group's 2021 takeover of then-Navistar.
Following more than five years of development alongside its Traton commercial truck siblings Scania, MAN, Volkswagen Caminhões e Ônibus and RIO, the all-new International S13 Integrated Powertrain was born.
The International S13 Integrated Powertrain is composed of the S13 engine, T14 transmission, and dual-stage aftertreatment system, and will be the final combustion product platform the company will develop as it transitions to zero-emission commercial vehicles.
The heart of the new Alabama-built powertrain is a 13-liter International S13 engine and its seven engine rating options, offering up to 515 horsepower and 1,850 lb-ft of torque. The entire powertrain is built in the heart of the deep south following a February 2020 groundbreaking on a 110,000 sq. ft. expansion of the company's Huntsville, Alabama, assembly plant. To date, more than 1 million engines have been built in Huntsville since the plant opened in 2008 and the company has its eyes fixed on building many millions more are its proprietary engine gains more marketshare.
Chet Ciesielski, International's vice president of highway heavy truck, noted the company previously skewed heavily in favor of the Cummins 15 liter engine, with a product mix of roughly 70%/30% of Cummins 15 liter power compared to International's prior 13-liter offering, the A26.
"We're pretty proud to say that that mix has shifted, and now it's more like a 60/40," he said. "Remember, we were just ramping up (production of the S13) at the beginning of the year, so we were kind of restricted. We expect to see that really go much higher as the next couple of years come upon us because the performance of the powertrain... We're we're expecting to see that 50/50 going into '25."
Driving that market growth is repeat business from early adopters, added David Hillman, vice president of integrated technology sales. "We haven't been in market with this powertrain for very long, [but] we've already got some customers that have liked so much of what it's been delivering for them and their operations that they're rewarding us with additional business," he said. "We see that mix shifting more toward our proprietary (13-liter) offering. Cummins is and will remain a great strategic supplier to us and a partner, but the S13 is really gaining some traction with us."
A new age throwback of aftertreatment
The technology in basically every diesel engine in the marketplace is a dual system based around some level of use of exhaust gas recirculation (EGR) feeding the SCR, yet the S13 brings to market a fully SCR system.
"It's a fundamental shift," Ciesielski added.
It's also a fundamental shift from then-Navistar's ill-fated fully EGR MaxxForce engines that hit the market in time for Greenhouse Gas 2010 regulations. Hillman said this time, with its Traton siblings, International was able to refine and bring to market an emissions solution first launched by Scania that is just as cutting edge, but has been validated and proven over millions of miles.
"We took the approach that we can make a big investment as part of a global group to do it right, and instead of incrementalizing something from the '90s that first added a little EGR, and then added other things, and then added SCR... and you're kind of like building on wings of a house," he said. "This is like investing in a brand new, clean sheet place to live."
And that new house comes minus one significant headache for service technicians: an ERG cooler.
"It becomes very customer centric because you're solving their problems by eliminating a pain point of an EGR cooler [and] eliminating a pain point of a variable geometry turbo with a just a wastegated, simple fixed turbo like from the 1980s," Hillman said. "So it becomes that customer centric thing that gives us the confidence because it's simplified and it's global."
"This is technology that's been used in the industry for decades prior," Ciesielski added, "because before EGR, everybody was just burning clean and [the engine was] doing its thing... This is old-style engine technology. How do we know it's going to work? It's going to work because you're taking one of the problem children in the industry – EGR – and you're taking it back out of the engine and letting the recirculation go away and you're letting the aftertreatment do its thing."
Designed with emissions regs in mind
Hillman noted the S13 engine was designed with eyes on the future, specifically the future of emissions. When engineers kicked off the development process in 2017, they had no idea what emissions regulations would be in 2027. All they knew is they would be tougher.
"We knew two things: We knew they were coming around that time, and we knew they were not going to get more lenient. They were going to get stricter," he said. "We designed this not to be an engine that we launched in '24 and have to completely redo in two or three years... We've got considerable (component) carry over (between model years)."
Hillman said he was recently at International's Huntsville engine plant where a handful of pre-production 2027 engines had just been completed, "and we ran them down the assembly line. We didn't have to tear apart the factory to build them because 90% of the parts, pretty much, are carrying over. We expect to be building, basically, the same powertrain that we are building today for the foreseeable future."
Chasing emissions standards in the years ahead will bring to the North American market parts, technologies and concepts from from Traton's global footprint, but "we are not changing the what the engineers call the form factor or the package envelope of the aftertreatment," Hillman added, "but we're maybe kind of tweaking some of the bits inside. But it's not getting bigger. It's not getting heavier. What I would characterize as tweaks to the base foundation (like variable valve timing). It's evolution, not revolution."
The 2027 EPA compliant engine will also eliminate what little remains of the EGR system. The EGR in use today is just to keep the catalyst warm in idle conditions and long idle.
"In today's model, we have an EGR crossover tube," Ciesielski said. "So that's a big one in '27. Believe it or not, there will be zero EGR pieces on our engine."
"The way it was designed, we don't have to do any sort of preheating of the gas," Hillman added. "We're hot enough in cylinder that we remain hot enough in the aftertreatment without any sort of pre-heat, which is why we're so confident with what we've got carrying us forward through '27 and beyond."
That the engine won't have be reinvented for the 2027 model year, Ciesielski said that simplifies maintenance in that technicians won't have to be retrained or have new tooling.
"Service, parts, workshop tools, technician training; all the stuff fleets are investing in now, they don't have to invest in again because it's all part of the roll over into '27," he said. "So it's a good segue into (model year 2027)."
An International transmission... finally
"A lot of people make damn good transmissions out there, so you've got to bring your A-game," he said. "That's something that we couldn't do as an independent."
The new gearbox is fully automated and was not adopted from an existing manual transmission.
With planetary gear sets in addition to typical bevel gears, the T14 transmission is 14 gears in a 12 gear package. "So we're able to kind of get the best of both worlds, where you've got the 14 gears to give you a wide ratio and also very even steps... Drivers don't know it but that's what they feel in the seat of the pants, and it also allows us to have a very short and lightweight package so that instead of just growing the length of the transmission case to add more gears, we're able to do it all because of the planetary gear set in there," Hillman said. "It keeps it short and compact, so it's able to be packaged and it drives super smooth."
Fuel efficiency gains
Built from the 12.7-liter displacement Scania Super, the low-rev, high-torque setup of the S13 engine allows for fewer fuel injections and lower fuel consumption – to the tune of about a 15% improvement in efficiency.
A 23:1 compression ratio, among the highest numerical compression ratios in the industry, helps ensure all the fuel in the cylinder is burned. That fuller combustion allows the fuel pump to operate at a lower pressure and use less fuel, "and a lower fuel pump pressure means less parasitic loss for the pumping," Hillman said.
Since there's a more complete and hotter combustion, there's no soot in the cylinder, eliminating diesel oxidation catalyst and a seventh injector.
"The payoff is, the only place diesel is going is into the cylinder to make power," Hillman said. "We're not putting any diesel anywhere else, like in the aftertreatment, to just do the Easy Bake Oven to cook off gunk that's accumulated there because we're not making as much gunk up in the beginning."
That, too, extends the life of the diesel particulate filter and other components.
