Five facts of 2027 X15 maintenance

In addition to improved fuel economy and reduced emissions, Cummins Inc.’s 2027 X15 is also easier and less costly to maintain than prior heavy-duty diesel engines from the iconic engine manufacturer. As part of the Cummins HELM™ platform, engineers worked hard to offer innovative solutions to meet future regulations. Cummins achieved that while offering up to 7% improvement in fuel economy when utilizing Cummins’ fully optimized powertrain.

The company boasts not only emissions and fuel economy improvements with the 2027 X15 but also an overall drop in maintenance costs.

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

Check out Five Facts of 2027 X15 Maintenance below to learn more about how historic performance gains were achieved while helping to improve the bottom line. 

1. Before and aftertreatment 

Engineers from Cummins Engine and Components segments partnered to create the Twin Module system used in the 2027 X15. 

Instead of increasing the length of current aftertreatment, two side-by-side SCR/DPF cannisters were developed to house the additional catalysts needed to get to 2027 emissions targets. That shorter design proved better for fitment and for reducing exhaust backpressure which led to 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.”

Two five kilowatt 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.

“The incorporated five-kilowatt heaters help us break free from being chained to engine operation for thermal management,” Holcomb explained. “Electric heat is considered supplemental heat for corner cases of operation. We will still dose diesel fuel to initiate regens and complete regens.” 

Cleaner emissions do not mean additional work. 

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

Improved emissions start with the engine. A closed crankcase ventilation system was introduced for the 2027 X15, which according to SAE International reduces emissions and oil loss. A new turbo from Cummins Turbo Technologies, a new piston design and rings plus increased coolant flow also contribute to more efficient combustion. The coolant flow is achieved through a modified cylinder head and block.
Aside from maintaining the drive belt, which is likely to align with other standard belt replacement, no routine maintenance is needed with the 48-volt system or heaters. DEF consumption is targeted for a 1% increase over the 2024 X15.

“Fortunately, the engine and aftertreatment work together to both limit NOx creation in the combustion chamber and convert what is produced in the aftertreatment,” Smith said. “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.” 

2. Don’t call it a ‘hybrid’

The engineers behind this system have an answer for any service managers who might hesitate at the thought of another layer of technology plus its higher voltage. They designed the 48-volt system to keep it safe and simple. 

“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.” 

There’s no regenerative braking either. A belt-driven, 48-volt alternator is dedicated solely to powering the SCR heaters while a separate alternator handles conventional power needs. Additional batteries or energy storing capacitators are not needed. 

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

The absence of 48-volt energy storage provides safer working conditions for technicians. 

“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. 

Smith noted that hybrids and batteries have their role to play on the long path to decarbonization, but the team had other ideas in mind for the 2027 X15. 

“By no means am I speaking poorly of hybrids or the use of batteries,” Smith said. “We are investing significantly in alternative powertrain solutions. In the 2027 X15, the focus was on delivering a simple and lightweight solution. Along with simplicity comes a degree of robustness.” 

3. More cost-effective oil maintenance

Maximizing oil health and life is a priority for the 2027 X15. First up, is the addition of a cartridge-style oil filter which will help lower maintenance costs while improving environmental stewardship. 

“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.

A cartridge will also be used for fuel filtration which will be addressed in a few paragraphs. The addition of an oil drain valve at the bottom of the cartridge shell helps make oil changes easier. Cartridges will not be limited to 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. 

Depending on duty cycle, it’s possible for oil change intervals to be extended with increased fuel efficiency. Lowering the number of hydrocarbons into the crankcase by way of more efficient combustion can extend oil life. 

“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. 

Base fuel economy improvement is 3 to 4% and can reach up to 7% when matched with a Cummins powertrain. Cummins Maintenance Monitor, introduced on the 2024 X15, is expected to be increasingly used as truck manufacturers step up their 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.”

The popular Cummins oil analysis program, Oil Guard, will still be available by request with the 2027 X15. 

4. Fueling up for success 

Improvements to the fuel system in the Cummins 2027 X15 have led to better fuel and maintenance efficiencies. A cartridge style fuel filter replaces a metal version which will reduce maintenance costs and lead to a greener profile. Fuel pressure has dropped to 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.” 

Holcomb explains that fuel injector service has also been made 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.”

5. Simplifying unplanned service

The new architecture of the 2027 X15 calls for new service training which will invite some easier paths to maintaining Cummins’ cleanest and most fuel-efficient heavy-duty diesel yet. Water pump replacement won’t be as labor intensive. 

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

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

The oil-lubricated fuel pump on the present-day X15 has been replaced with a fuel lubricated model. A fuel lubricated pump allows for a more compact design along with minimal leakage and no oil-to-fuel transfer pressure which reduces injector damage from high pressure and hot fuel leakage. 

Cummins assures that any system with a significant change will be coupled with updates to service literature. 

According to Cummins, the 2027 X15 will continue to offer similar ratings as its legendary predecessor but that lowering the total cost of operation was a key deliverable for the emerging product.