Expect simplified maintenace with cleaner Cummins 2027 X15 diesel engine

What you'll learn in this article:

About Cummins' latest 2027 X15 diesel engine
How the 2027 X15 features a new aftertreatment system to decrease emissions
How the 2027 X15 uses a new cartridge oil filter to reduce costs and make maintenance easier

The 2027 X15 diesel is part of a growing lineup of more efficient and capable engines from Cummins that meet the most demanding emissions rules ever set by EPA and the California Air Resources Board.

Other on-highway engines introduced through the Indiana-based company’s HELM platform include the natural gas X15N, hydrogen-fueled X15H, medium-duty X10, a new 6.7 turbo diesel and its first gasoline engine, the 6.7 Octane. That’s six engines introduced over the past two years that can meet 2027 EPA and CARB regulations.

Cummins' latest workhorses also offer more capability with less fuel. Internal combustion clearly has plenty of life left to give as zero-emission technologies steadily gains ground.

Maintenance is another critical area of improvement, as noted here with the 2027 X15.

“If we focus on month-to-month operation, there are TCO savings over current product [2024 X15],” said Jared Holcomb, Cummins X15 Product Manager.

Couple that with a big reduction in emissions alongside fuel savings of up to 7% and the 2027 X15 delivers plenty of gains for fleets and owner-operators alike.

Cleaner aftertreatment with no additional maintenance

Effective aftertreatment is, of course, critical to diesel emissions reduction. With no suitable solution available on the market, Cummins created its own for the 2027 X15. The Twin Module system uses side-by-side SCR/DPF cannisters to house additional catalysts required to meet 2027 emissions goals.

The parallel cannisters not only improve fitment through a shorter design, they also reduce exhaust backpressure which ensures greater energy efficiency.

“The engines can breathe easier through it,” said Andy Smith, product management leader for Cummins Emissions Solutions Marketing. “If we can make the aftertreatment easier to breathe through, then that's horsepower not devoted to pumping exhaust out the tailpipe and putting it toward the wheels.”

For major NOx reduction, engineers incorporated two five-kilowatt heaters inside the twin module. A separate 48-volt system more quickly heats and maintains ideal temperatures inside the Twin Module over engine heat alone.

“Electric heat is considered supplemental heat for corner cases of operation,” Holcomb explained. “We will still dose diesel fuel to initiate regens and complete regens.”

Two 5-kW heaters rapidly heat the Twin Module and maintain optimum temperature for major NOx reduction, while a separate 48-volt system powers the heaters. Experts describe a faster process over solely relying on engine heat, which is slow to rise on startup and will fluctuate depending on duty cycle.

Even as additional catalysts are put to work to further clean emissions, diesel particulate filter (DPF) maintenance intervals are expected to remain unchanged.

“We are still targeting the same DPF maintenance intervals [as those on the 2024 X15],” Holcomb said.

Upstream at the engine, Cummins added a maintenance-free closed crankcase ventilation (CCV) system, which SAE International reports will reduce emissions and oil loss. More efficient combustion is gained through a new turbo, new piston design and rings, and increased coolant flow courtesy of a modified cylinder head and block.

“Improvements in the engine better control NOx creation, which is why the aftertreatment only requires a small 1% increase in DEF consumption despite the drastically lower NOx limits,” Smith said.

48 volts doesn’t make it a hybrid

In addition to a conventional voltage system, the 2027 X15 features a battery-free 48-volt system which powers the aftertreatment. It’s a safe and simple design requiring little attention.

“In most instances in North America, anytime you have more than 12 volts or 24 for some buses and such, you would be speaking of a hybrid, but this is not a hybrid system per se,” Smith said. “One of our focuses of introducing the 48-volt system is that we do not, for example, have a battery.”

The belt-driven 48-volt alternator powers only the SCR heaters. A separate alternator does the rest. The drive belt is likely to align with other standard belt replacement. No extra batteries or energy storing capacitors are required.

“We did not want to add those as a source of weight or maintenance and potentially expensive replacement costs,” Smith said.

By not incorporating 48-volt energy storage as some systems do, the 2027 X15 can help alleviate risk and provide better peace of mind.

“It was highlighted to me by a user about one of the differences they saw with our 48-volt system is the comfort during maintenance since it doesn’t have a battery,” Smith said.

Lower cost oil maintenance

To help optimize oil life, and reduce costs and waste, Cummins introduced a new cartridge oil filter replacing the prior metal body design. (The fuel system also gets a new cartridge design. More on that below.)

“The benefit becomes lower replacement cost at each oil drain interval and also the elimination of environmental waste from not having to discard the metal can [on preceding X15 models],” Holcomb said.

Techs will appreciate a handy oil drain valve that’s positioned at the bottom of the cartridge shell. Cartridges will be available outside Cummins.

“We expect the aftermarket to support oil and fuel filters in the future, that way customers will have the choice to work with their preferred supplier once they're available,” Holcomb said.

The increased fuel efficiency of the 2027 X15 can also extend oil change intervals since fewer hydrocarbons will be introduced inside the crankcase. Base fuel economy improvement is 3 to 4% and can reach up to 7% when matched with a Cummins powertrain.

“As you increase fuel efficiency numbers, you tend to bump into the next service interval. Not only will customers be getting better fuel mileage, but they should also be able to extend their oil drain intervals in line with that fuel efficiency improvement,” Holcomb said.

Oil drain intervals can also get a boost through increased use of the Cummins Maintenance Monitor. Introduced on the 2024 X15, this cost-cutting monitor is expected to gain wider use as truck manufacturers integrate more digital capabilities.

“We don't believe that, at this moment, we're getting full utilization out of the ‘24 Maintenance Monitor release because some OEM dash integrations do not enable utilization.” Holcomb said. “With ‘27, there will be further smart dash integrations. We're hoping that picks up steam so that customers can leverage the benefits. We can save people money; we can use less oil and we can be more environmentally friendly. I think it's really important to realize the Cummins’ offerings that are out there.”

Cummins' popular oil analysis program, Oil Guard, will also be available with the 2027 X15.

Fuel system gets better

The Cummins 2027 X15 has also improved fuel and maintenance efficiencies. The metal fuel filter on the prior model has been replaced with a cartridge which cuts costs and waste. Fuel pressure is lower at 2400 bar.

“Why is that important?” Holcomb asked. “By being able to obtain injection that meets emissions at a lower pressure. That helps us with our overall efficiency scheme. By slightly lowering our injection pressure, we pick up additional efficiency. That's what we've done. We've slightly lowered the injection pressure to pick up efficiency and reduce parasitic losses from the injection pump.”

Fuel injector service will also be easier.

“Now they no longer have the injector connector tube at the side of the injector,” Holcomb said. “The injector just has two mount bolts and the fuel line threads directly into the side of the injector so there's an elimination of a part and a torque process.”

Unplanned service made easier

Techs will be interested in new service training which will show how new design changes on the 2027 X15 will make for easier service. For example, less labor will be required for water pump replacement.

“Now those can be accomplished without removing the vibration damper so that should save customers time,” Holcomb said.

Other service training “will cover changes such as the dual overhead cam arrangement, the rear gear drive and changes to the fuel pump,” Holcomb continued.

Another notable change is the fuel pump. The present-day X15 features an oil-lubricated model. The 2027 X15 is equipped with a fuel lubricated pump which allows for a more compact design. It also minimizes leakage and with no oil-to-fuel transfer pressure, there’s a reduction in injector damage from high pressure and hot fuel leakage.

Any system that has undergone a significant change will be accompanied with service literature updates.

While focusing on lowering the total cost of operation for the 2027 X15, Cummins reports that its latest heavy-duty workhorse will offer similar power ratings as its predecessor.