Bottom Line
Coming soon: Paccar’s new MX engine
Paccar officials claim the new MX diesel engine will last nearly twice as long as competitors' engines before needing a major overhaul.

By Suzanne Stempinski
field editor


At the Paccar Technical Center in Mount Vernon, WA, in February, I had the opportunity to get up close and personal with the new MX engine and check out its performance on the test track. Along with the Cummins engines, the MX will power Paccar’s Petes and KWs.

With horsepower ranging from 280 hp to 485 hp and torque ratings up to 1,750 lbs.-ft., the 12.9-liter Paccar MX is positioned for both vocational and over-the-road applications.

With eight configurations to choose from that day, I slid into four – a Pete 388, a Pete 384, a Kenworth T660 and a DAF XF105. 

While the transmissions and axles, suspensions and wheel bases were all different, the most striking feature in each and every truck was the quiet. The absence of noise from the engine and proprietary engine brake was impressive. I could carry on a conversation at a whisper. Overall, I liked what I heard.

Advances in technology come with a hefty price tag. Investing more than $1 billion in engine technologies over a 10-year period has enabled Paccar to keep pace with Environmental Protection Agency mandates and to anticipate future emission requirements. According to Mark C. Pigott, chairman and chief executive officer, a long-term goal is to offer a complete Paccar power train. 

More than 50 million miles in real world testing during the past five years has gone into the MX, including severe condition testing in Yellowknife, Northwest Territories (40 degrees below 0); the high mountain elevations of Colorado; and brutal summer heat environments in California and Arizona. Today, more than 125,000 Paccar MX engines are operating in DAF trucks globally.

Highlight features of the MX include a significant weight reduction due to the use of compacted graphite iron in the engine block and head; design simplification through component integration; anticipated engine life of 1 million miles (90 percent will reach that mileage); electronic fuel injectors that operate at up to 2500 bar injection pressure (roughly 3600 psi); fractured cap technology for connecting rods and main bearing caps; and the use of Selective Catalytic Reduction (SCR) in combination with Exhaust Gas Recirculation (EGR).

Later this year, Paccar’s new engine factory in Columbus, MS, will open. That’s where they will build the engine. The MX is being tested right now on American trucks and can be ordered for summer delivery. LL


Suzanne Stempinski can be reached at