When procuring hydrogen engines (H2-ICE), you must prioritize Power Density, Thermal Efficiency, and Injection Technology. Ensure the engine utilizes High-Pressure Direct Injection (HPDI) or sophisticated Port Fuel Injection (PFI) systems to prevent backfiring. Verify that the Compression Ratio is optimized (typically between 12:1 and 15:1) to balance efficiency with the risk of pre-ignition. Additionally, confirm the NOx emission control systems, such as Selective Catalytic Reduction (SCR), are integrated to meet international environmental standards.