Ultra Low Particulate Matter Combustion, or ULPC. It optimizes the design of the piston bowl, fuel injectors, cylinder head and other components to use the oxygen as much as possible in the combustion chamber

The new engines have fixed valve timing, a maximum of five injections per cycle with 26,000-psi injectors, and an optimized single turbocharger. EGR rates were increased in some engine operating points (rpms and torque loads) and reduced in others to optimize engine performance, fuel economy and emissions reduction.
A maintenance-free diesel oxidation catalyst (DOC) was developed for high efficiency removal of the soluble organic fraction of the particulate matter (PM) throughout the engine’s lifetime. Any catalyst will deteriorate from exposure to exhaust,

Doosan’s new engines

• D18, 1.8-liter, three cylinders, 50 horsepower
• D24, 2.4-liter, four cylinders, 74 horsepower
• D34, 3.4-liter, four cylinders, 100 horsepower