In America, the typical mpg of a semi truck sits firmly in single-digit territory. Effectivity enhancements imply that at the moment’s vans now common round seven mpg, however some states nonetheless see vans reaching lower than six mpg. Utilizing much less gas is not simply environmentally pleasant; there are monetary incentives too. The worth of diesel has risen significantly over the previous twenty years, and so even a small gas saving can lead to massive value financial savings over time.
A key a part of making engines extra frugal is maximizing their brake thermal effectivity, or BTE. Basically, BTE is a measure of how effectively an engine can convert gas into energy — the upper the BTE proportion, the extra energy an engine could make with the identical quantity of gas. In 2024, Chinese language diesel engine maker Weichai unveiled the Weichai WP13H, an engine with a BTE of 53.09% on the World Congress on Inner Combustion Engines.
This was a report for a manufacturing engine, and a notable enchancment on the business common of 45-46% BTE. To substantiate the report, the determine was licensed by the German testing organisation TÜV SÜD and the China Automotive Know-how and Analysis Heart. Weichai had quickly improved its engine expertise over time, first unveiling an engine with 50.23% BTE in 2020, then launching improved variations yearly till the 2024 announcement. The record-breaking engine was a Weichai WP13 sequence engine, which is obtainable in China for semi vans in addition to dump vans.
Weichai’s engine can save a major quantity of gas
To create its record-breaking engine, Weichai made a variety of small adjustments from its earlier engine design. It revised the design of its turbocharger to optimize its circulate, improved its gas injection, and lowered the friction between engine parts wherever potential. The ensuing design meant that operators may scale back their gas prices by 14% in comparison with the business common, in keeping with the model’s estimation.
Weichai has continued to enhance its engine design for the reason that 2024 announcement, unveiling a brand new technology of its WP truck engines in April 2025. This newest technology provides the identical 53.09% BTE because the record-breaking 2024 engine however with lowered engine weight and a give attention to longevity. In keeping with the model, its newest WP14 and WP15 engines are designed to final round 1.37 million miles. For context, the typical semi truck engine lasts round 750,000 miles earlier than needing a rebuild.
Whereas the Chinese language producer holds the BTE report for a manufacturing engine, famed American diesel engine producer Cummins has developed a prototype engine with a good greater BTE. Again in 2021, Cummins introduced that its SuperTruck II venture had achieved 55% BTE, though it has but to make that stage of effectivity accessible to clients.
