Our trucks are powered by high performing engine solutions from leading manufacturers, Detroit and Cummins, and have been custom fit to Western Star trucks to ensure you get maximum power and reliability. Whether you’re hauling fuel, livestock, or freight, our selection of innovative and powerful Detroit and Cummins truck engines are the driving force behind your Western Star. 

Technologically-advanced, reliable, and efficient are just a few words we would use to describe the engines of our rugged Western Star trucks.


Over the years Detroit has established its reputation as a manufacturer of some of the most reliable and innovative diesel engines for a variety of applications.


Building upon the legendary Detroit heavy-duty engine legacy, the DD13 Gen 5 engine takes efficiency and performance to the next level. Whether powering a Western Star 47X or 48X, the DD13 Gen 5 hauls with exceptional performance and low total cost of ownership.

Horsepower450-525 HP
Peak Torque1,550-1,850 LB-FT
Displacement12.8 L
Western Star Trucks Models47X, 48X


The DD16 engine is the biggest, most powerful truck engine Detroit has ever built. With a wide, flat toque curve, and delivering up to 2050 lb-ft and 600 hp, it tackles your hardest jobs while performing with the fuel efficiency and reliability you’ve come to count on from Detroit.

Horsepower500-600 HP
Peak Torque1,850-2,050 LB-FT
Displacement15.6 L
Western Star Trucks Models48X, 49X

For more than 100 years, Cummins has created the power solutions people depend on.


The L9 is the total package. No other engine in its horsepower range has this combination of power, proven reliability and durability.

HorsepowerUp to 380 HP
Peak TorqueUp to 1,250 LB-FT
Displacement8.9 L
Western Star Trucks Models47X