ORNL Alloys Help Enable Lighter, More Fuel-Efficient Truck Engines

Researchers at the Department of Energy’s Oak Ridge National Laboratory have developed high-temperature aluminum alloys that met the strength and durability requirements of General Motors’ new low-mass, high-efficiency medium-duty truck engine.

The materials were tested under a cooperative research and development agreement between ORNL and GM. According to ORNL, the two alloys helped the prototype engine achieve a more-than-10-percent improvement in fuel efficiency and a 15-percent reduction in weight.

The work focused on two ORNL-developed materials: cast ACMZ, also known as AlCuMnZr, and printed DuAlumin3D. ACMZ was used to cast the engine’s cylinder heads and engine block, while DuAlumin3D was developed for high-performance pistons.

Commercial truck engines, including those used in vehicles such as the Chevrolet Silverado 3500, must withstand heavy loads and long periods of use. Materials strong enough for those conditions are often dense, which can reduce fuel efficiency. Lighter metals can improve mileage, but many commercially available lightweight options struggle with the high temperatures and pressures of high-performance engines.

ORNL said the new alloys address that tradeoff by combining lower weight with high-temperature durability. ACMZ is described as a high-strength, affordable aluminum alloy designed for heat and stress, while DuAlumin3D is a 3D-printable structural aluminum alloy designed for strength and durability at extreme temperatures.

“The shared goal between ORNL and GM was to demonstrate next-generation engines for high-volume trucks that are lighter, lower-cost, and more efficient, all without sacrificing power and performance,” said Allen Haynes, director of the ORNL-led Transportation Technologies Office Powertrain Materials Core Program consortium.

The alloys, along with advanced combustion and other materials and manufacturing technologies, enabled GM’s prototype LMHE engine to pass performance and durability tests. The GM-led team, which included ORNL and several suppliers, received a 2025 R&D 100 Award and a DOE 2025 Team Award for the work.

“This is a remarkable set of combined outcomes by the GM design team,” said ORNL’s Amit Shyam, who leads the Alloy Behavior and Design Group. “Any weight shaved off an engine equates to more miles per gallon for the average driver, saving not only energy, but money.”

ORNL said its accelerated alloy design approach can move a targeted material concept into prototype applications in two to four years, compared with the 10 to 15 years historically required.

Article & Image Source: Oak Ridge National Laboratory