New Volvo D13 VGT Utilizes 24V Architecture

Volvo Trucks North America launches the all-new VNR with standard D13 VGT engine and also announces an upcoming CARB-24 Omnibus compliant engine variant.

May 21, 2025

Ryan Gehm

The new Volvo D13 VGT (variable geometry turbo) engine builds on improvements launched with the D13 Turbo Compound engine, including a seven-wave piston that allows for greater heat dispersion across the top of the piston head, lowering temps and reducing NOx output. (Volvo Trucks North America)

When Volvo revealed its all-new VNR regional haul truck in March 2025, it also marked the launch of something new under the hood: the Volvo D13 VGT (variable geometry turbo) engine. The new D13 VGT engine will be standard in the VNR and optional for the VNL day cab.

The Volvo D13 VGT engine will be standard in the new VNR (shown) and optional for the VNL day cab. (Volvo Trucks North America)

The D13 VGT engine builds on improvements launched with the D13 Turbo Compound engine, which is standard on the new VNL that commenced commercial production at the New River Valley assembly plant in Dublin, Virginia, in October 2024.

The new VNR is up to 7.5% more fuel efficient than the legacy truck, with 3% of that attributable to the powertrain, according to Magnus Koeck, VP of strategy, marketing and brand management at Volvo Trucks. The seventh generation of Volvo’s I-Shift automated-manual transmission provides 30% faster shifting speeds for better acceleration and contributes to overall vehicle efficiency, he said.

A key enhancement for the D13 VGT engine is the seven-wave piston that optimizes air and fuel mixture control, resulting in more efficient combustion. Shorter piston height and a longer connecting rod minimize cylinder sidewall pressure and reduce friction. The seven-wave design also allows for a greater dispersion of heat across the top of the piston head, lowering the overall temperature and reducing NOx output.

Improvements to the fuel injection system include smaller needle control valves in the fuel injectors for precise control over the fuel flow rate. This enhancement leads to improved fuel atomization, better combustion efficiency and enhanced engine performance, according to Volvo. A variable displacement oil pump is another critical element, Koeck said. It adapts to the engine’s oil pressure demands, reportedly minimizing parasitic losses and reducing wear and tear.

“As we continue to innovate and improve our powertrain offerings, the launch of the Volvo D13 VGT engine marks another significant step forward in our commitment to fuel efficiency and sustainability,” said Peter Voorhoeve, president of Volvo Trucks North America. “Fuel costs remain the second highest expense for fleets in North America, and our powertrain improvements represent an up to 3-percent fuel efficiency improvement over our previous-generation engine.”

The 24-volt electrical system is an “enabler” for safety technology, Volvo Dynamic Steering (shown on the new VNL) and further development of autonomy. (SAE/Ryan Gehm)

Available for order in the new VNR and VNL models, the Volvo D13 VGT engine offers 405, 425, 435 or 455 hp (302, 317, 324 or 339 kW), with torque ratings ranging from 1,450 to 1,850 lb-ft (1,966 to 2,508 Nm). The D13 Turbo Compound engine launched last year in the VNL is also available and is “well suited” for fleets using the VNR in highway applications, Koeck said.

24V architecture an enabler

The all-new VNL was Volvo Trucks North America’s largest investment ever, Voorhoeve said during the VNR launch at ATA’s Technology & Maintenance Council meeting. “Not only did we develop a new truck, we developed a new platform. A new platform for all the trucks that would come,” he said. The VNR is the second truck on this new platform, offering the same connectivity and safety packages as on the VNL.

A new “intelligent” battery management system shown on the VNL pairs 12V batteries connected in series to make 24V. (SAE/Ryan Gehm)

The new D13 VGT engine utilizes the 24-volt electrical system that Volvo first introduced in North America with the new VNL. Already proven on its trucks in the European market and elsewhere, the 24-volt electrical architecture is an “enabler” for safety technology, Volvo Dynamic Steering (VDS) and further development of autonomy, Koeck said at the VNL media event in June 2024. “There are certain enablers such as the new electronic architecture in order for us to turn on the features, so to say.”

The electrical architecture also paves the way to use lighter components and can prolong the life of those components, according to Steven Walker, director of uptime support at Volvo Group. “It has 24 volts, which allows us to have less amperage going through the lines, which is less heat. Less heat through those lines means you can have smaller lines, which is less weight. And heat is what kills components, so they will last longer,” he said.

Referencing the new VNL, Walker added that “we can’t talk about electrical architecture without a new battery management system. This is a very intelligent system,” he said, noting that pairs of 12V batteries are connected in series to get to 24V. “This battery management system looks at parasitic loss, looks at state of charge, and it can actually start turning things off so it won’t degrade the batteries too bad. It’ll also start the engine automatically and recharge those batteries if it gets down to a certain level.”

Cab accessories and trailer connections still require a 12V auxiliary supply voltage.

Additional benefits of the new 24V electrical system are the ability to diagnose potential problems more easily and to transmit ECU data via telematics for remote monitoring of fault codes.

Volvo Trucks’ new CARB-24 Omnibus compliant engine (upon certification) features a fully serviceable linear exhaust aftertreatment system, which includes the DOC, DPF, SCR and an integrated 48-volt heater. (Volvo Trucks North America)

“Remote diagnostics is looking for potential fault codes in the trucks 24/7,” Chayene De Souza, product marketing manager for safety and connectivity at Volvo Trucks, said last year at the VNL media event. “When a fault code is identified, it’s classified as either yellow or red. Red means the truck has to come out of service immediately. Immediate attention is needed. If the fault code is yellow, that means the truck does not have to come out of service. Think about the power of that information.”

De Souza said the new platform made the move to 24V possible. “It would be very hard to [switch to] 24 volt or any change of voltage that’s that big in an existing platform. Of course we looked at that, at the very beginning when they came to us in 2017,” she said. “We looked at the amount of work and the amount of bridge solutions we would need to do for something like that versus starting from scratch and building a truck that can be the platform for so many new technologies.”

CARB-24 Omnibus compliance

Volvo Trucks North America announced at the 2025 ACT Expo that it’s applying for certification of a CARB-24 Omnibus compliant engine that will be built on the new D13 VGT engine platform. Expected to meet the California Air Resources Board’s 2024 emissions standards, the variant is designed to obtain a certification at the 0.05-g NOx rating with reduced particulate matter (PM) emissions.

Once certified, customers will be able to order the CARB-24 Omnibus compliant engine in the new Volvo VNL and VNR models, with expected available configurations of 425 hp (317 kW) and 1,750 lb-ft (2,373 Nm) or 455 hp (339 kW) and 1,850 lb-ft (2,508 Nm). Deliveries of new trucks with the compliant engines are expected to begin in Q4 2025.

Volvo Trucks’ new engine will feature an advanced emission control system, including a fully serviceable linear exhaust aftertreatment system (EATS) and an integrated 48-volt heater used during startup and low-load situations to achieve the ultra-low NOx targets. Each component, including the diesel oxidation catalyst (DOC), diesel particulate filter (DPF), aftertreatment heater and selective catalytic reduction (SCR), is designed for individual servicing or replacement.

CARB’s Omnibus regulations aim to reduce NOx emissions by 75% and PM by 50% compared to current U.S. EPA standards, from heavy-duty on-road engines for engine model years 2024 through 2026.

“To help customers successfully navigate evolving regulations, Volvo has developed an engine that is intended to meet both EPA and CARB requirements,” said Johan Agebrand, director of product marketing, Volvo Trucks North America. “We continue to invest in powertrain and vehicle advancements that support our sustainability goals and our commitment to environmental stewardship.” The company says the new engine is part of its path toward zero emissions in heavy-duty transportation by 2040.