Which piston crown design is most commonly used by OEMs in today’s highway diesel engines?

The Mexican hat piston crown design is most commonly utilized by OEMs in today's highway diesel engines due to its efficiency in promoting complete combustion. This design allows for better air-fuel mixing and enhances the efficiency of the combustion process. The shape of the Mexican hat crown helps to create optimal turbulence in the combustion chamber, leading to a more uniform and efficient burning of the fuel. This results in improved engine performance, reduced emissions, and better fuel economy, which are crucial factors for modern highway diesel engines aiming to meet stringent environmental regulations.

Other designs, while having their benefits, may not offer the same balance of efficiency and performance that the Mexican hat design provides, making it the preferred choice among manufacturers.