Street Smarts: Volvo, Mack detail new EPA 2027 diesel engines

Volvo Trucks North America used ACT Expo 2026 to pull the wraps off its next-generation Volvo D13 diesel engine for EPA 2027 emissions regulations. Its sister company, Mack Trucks, also unveiled its own version of the same core platform at the show, with the new Mack MP13 tailored for vocational and highway customers.

Volvo’s 2027 D13 will offer ratings from 405 hp and 1,450 lb.-ft. of torque up to 540 hp and 1,950 lb.-ft. of torque. Engine braking also gets a substantial boost, climbing to 630 braking horsepower. (Photo: Volvo Trucks)

Together, the announcements offered one of the clearest looks yet at how major truck makers plan to meet the EPA’s stringent 2027 nitrogen oxide (NOx) emissions limits without sacrificing fuel economy, performance or drivability.

Both engines are built around a new compact graphite iron engine block. Additional design features include upgraded combustion systems, revised piston designs and advanced fuel injection systems. All those advancements are coupled with heavily updated aftertreatment packages designed to meet the EPA’s upcoming 35-milligram NOx standard across all 50 states and Canada.

Volvo officials said the new D13 cuts NOx emissions by more than 80% compared to current standards while maintaining and, in some applications, improving fuel efficiency.

“We wanted to not affect fuel economy, performance and also total cost of ownership,” said Duane Tegels, Volvo powertrain marketing manager.

That balancing act has been a major concern for the trucking industry since California first began pushing low-NOx standards nearly a decade ago. Engine makers initially warned regulators that there was a significant tradeoff between ultra-low emissions and fuel economy.

Instead, the newest generation of heavy-duty diesel engines appear poised to deliver gains in both.

More power, better fuel economy

Volvo said fleets currently operating its turbo-compounding engines should see fuel economy comparable to today’s models, while customers moving from the company’s variable geometry turbocharger platform could see as much as a 4% improvement in fuel economy.

The new D13 will offer ratings from 405 hp and 1,450 lb.-ft. of torque up to 540 hp and 1,950 lb.-ft. of torque. Engine braking also gets a substantial boost, climbing to 630 braking horsepower.

The new Mack MP13 delivers up to 540 hp and 1,950 lb.-ft. of torque, while improving fuel efficiency by as much as 3% compared to the previous MP13. (Photo: Mack Trucks)

Mack’s version of the platform mirrors many of those core specifications. The new MP13 also delivers up to 540 hp and 1,950 lb.-ft. of torque, while improving fuel efficiency by as much as 3% compared to the previous MP13. The engine brake similarly jumps to 630 braking horsepower, a more than 20% increase over the current engine.

“The MP13 is essentially the same platform as Volvo’s new D13 EPA 2027 engine, but with horsepower and power curves designed for Mack customers,” said Govi Kannan, Mack’s senior vice president of global product owner.

Kannan said the new engine features an optimized torque curve that delivers peak torque at just 900 rpm to support downspeeding strategies and improved drivability. The engine also incorporates a more efficient turbocharger and predictive software designed to smooth throttle response.

Both engines rely on a significantly revised combustion system.

Tegels said the compact graphite iron block delivers 75% greater tensile strength than the previous design, while allowing engineers to increase cylinder pressures and raise compression ratios from 18:1 to 20:1.

The engines also move to a new high-pressure common rail fuel system operating at up to 35,000 psi.

Advanced aftertreatment systems

Meeting EPA 2027 standards requires substantial aftertreatment upgrades, particularly to control emissions during cold starts, idling and low-load operation.

Both Volvo and Mack are adding heater systems to their aftertreatment packages to maintain operating temperatures and improve diesel exhaust fluid (DEF) conversion efficiency.

Jack Roberts is a Tuscaloosa, Ala.-based independent journalist and licensed commercial driver with more than 20 years’ experience covering the North American and global trucking industries.

Volvo’s aftertreatment system integrates pre-heating technology, a diesel oxidation catalyst and diesel particulate filter, along with dual selective catalytic reduction chambers in a compact package.

“There are two grid heaters in the aftertreatment system,” Tegels explained. “They’re to maintain heat in there and reduce the DEF into ammonia during that cycle.”

The aftertreatment heaters operate through a 48-volt electrical system used primarily during startup and light-load operation.

The Mack MP13 also expands fuel compatibility, allowing fleets to operate on renewable diesel (R100) and biodiesel blends up to B20, compared to B10 on the previous engine.

Opening soon

Volvo said the new D13 will power its next generation of highway and regional haul trucks, while Mack said orders for EPA 2027 MP13-powered trucks are expected to open in August 2026 ahead of production for model year 2028 vehicles.