With the launch of Kenworth’s T680 Next Generation truck model, also comes the 2021 Paccar MX-11 and Paccar MX-13 engines for Kenworth’s Class 8 truck lineup.

Both engines feature re-designed internal components to enhance fuel economy – up to 2.4% in the MX-13, and 3.4% in the MX-11 – depending on the application and specification, Paccar officials said in a press release.

The Paccar MX-11 can now be spec’d with a higher horsepower rating of up to 445 hp at 1,700 lb.-ft. of torque at 900 RPM. The Paccar MX-13 can be spec’d up to 510 hp at 1,850 lb.-ft. of torque at 1,000 RPM.

The engines can be paired with the 12-speed Paccar TX-12 transmission, Kenworth predictive cruise control, and Paccar DX-40 axles for enhanced performance, Paccar officials said.

The engines feature optimized combustion with multi-pulse fuel injection. A smaller, more efficient turbocharger boosts power and improves responsiveness, according to the company. And an enhanced piston design has added features to reduce frictional losses. 

Paccar’s next generation aftertreatment system completes the system to further reduce particulates and nitrogen oxides.

The engines also were updated for added reliability. An enhanced fully-encapsulated engine harness protects against the elements, while connections were reduced between the engine and vehicle. Inside the engine, several structural enhancements were added to strengthen components and optimize rigidity.

To make fuel filter changes more efficient, Paccar now mounts primary and secondary fuel filters on the engine, instead of on the chassis. And, a 12-volt fuel heater comes standard for improved cold weather performance.

Extended service intervals of up to 75,000 miles for both the oil and fuel filter combined with major components warranty, which is five years or 500,000 miles, results in best-in-class performance and service intervals, Paccar officials said.