For 2021, Cummins is launching enhanced versions of its Class 8 on-highway X12 and X15 engine lineup, which are designed for better overall efficiency, total cost of ownership, and uptime, and to be compliant with the Phase 2 greenhouse gas emissions rules set by the Environmental Protection Agency (EPA) that will cover 2021 to 2027.
“Cummins’ 2021 heavy duty products were designed with three core deliverables in mind: increased uptime, better overall total cost of ownership, and improved drivability,” said Brett Merritt, vice president of the Cummins' On-highway Engine Business. “By delivering on these focus areas, Cummins’ products will offer better performance for the customer’s bottom line.”
Now, all of the X-Series engines will be afforded the same innovations introduced with the 2020 X-15 Efficiency Series, including improvements to fuel efficiency and oil change intervals. For those engines holding EX ratings (spec’d with the Endurant HD automatic manual transmission and GPS look-ahead data) additional efficiency increases and drivability features, including onramp boost predictive engine braking, predictive gearshift, and dynamic power, will be unlocked.
On-ramp boost: This is a safety feature that removes fuel economy controls to achieve safe speed to merge onto the highway, applying max torque when in the top six gears.
Dynamic power: Limits acceleration, not torque, based on load to prevent large deviations in performance from grade to grade.
Predictive gear-shifting: Downshifts at bottom of the hill to ascend as efficiently as possible without constant shifting.
Predictive braking: Even if the driver underestimates the load or misses a speed grade sign, this feature engages max braking from the start for the better control of the vehicle.
Some OEMs have reported to Cummins that nearly half of their X15 Efficiency Series engines spec’d by customers are EX rated.
“That in itself speaks volumes for the new features being released, and the adoption rate from customers,” Merritt said.
The X12 and X15 were launched in 2017 for EPA-compliance and to be a more “finely tuned” version of the ISX engines. Through their introductory period, Merritt said Cummins’ engine market share was 30 percent. They have also owned the 100-year-old company’s highest “zero touch rating” of any product, which measures how many engines complete the base warranty period without requiring service. The “repairs-per-hundred” metric was also lowest in Cummins product history.
This indicates trucks with these Cummins engines will spend less unplanned time in the maintenance bay, though Cummins also has targeted reducing planned time as well. The Efficiency Series engines have a 75,000-mile oil drain interval when customers average 7 or more mpg.
An optional longer fuel filter for the X12, available on certain Autocar, Freightliner and Western Star trucks, among others, will allow customers to sync fuel filter and oil change intervals.
Now, Cummins' Performance Series has also seen a boost.
“We've increased the oil change interval by 10,000 miles for customers getting 6 to 7 miles per gallon as well as those getting 5 to 6 miles per gallon,” explained Nick Roth, Cummins' director of national accounts. “Customers who want to extend their interval further can participate in the Cummins oil guard oil analysis program, which can extend their trucks up to 100,000 miles before needing new oil.”
He added the “X15 and X12 engines have the industry's lowest maintenance costs through the first 500,000 miles.”
Cummins sells 70 percent Efficiency and 30 percent Performance Series overall.
An optional air compressor resonator can also lower engine noise while idling and in operation.
The 2020 X15 Efficiency Series (400 to 500 hp) was notable for its 3.5 percent increase in fuel efficiency across the board over its 2019 predecessor, and an extra 1.5 percent with the EX rating for 5 percent total. Improvements to the EGR cooler and turbocharger facilitated this.
The X15 Performance Series (525 to 605 hp and 2,050 lb.-ft. peak torque) now has a 2 percent better fuel efficiency than in 2017. The Performance Series will also now be offered with SmartCoast, Predictive Cruise Control and Predictive Road Speed Governor (if paired with an automated manual transmission).
Trucks powered by the new X12 engines, good for line haul, regional and vocational applications, should see a 2.5 percent uptick with the base model and 4 percent overall with the EX rating. Kris Ptasznik, heavy duty on-highway product manager, explained increased compression ratios and reduced frictional losses through modified ring packs led to the improvements.
“Select customers [are] routinely seeing or exceeding 9 miles per gallon with both our X12 and X15 engines,” Roth said.
RaNae Isaak, Cummins Powertrain & TCO Consultancy Leader, said using Smart Coast, cruise control and Smart Torque 2 strategy can lead to fleets getting more than 10 mpg.
Additionally, Cummins has made its PowerSpec tool available online, called PowerSpec Web. Previously it was only accessible on a PC and required a download.
“Cummins has really focused on making the spec’ing process easy to use, with built in filters to help select the appropriate transmissions and axles based on the equipment customers are considering,” Isaak said. “Additionally, the feature description tool helps inform fleets and drivers of the interaction between features, and the hardware or software requirements needed to enable specific features.”
