Heavy-Duty Truck and Bus Engines

Emission standards for new heavy-duty truck and bus engines are based on the European standards. Regulation GB 17691-2005 specifies the emission limits for China III-V stages, which are based on Euro III-V, respectively. The emission limits are shown in Table 1.

The following provisions apply to emissions of ammonia and nitrogen dioxide:

• NO₂ requirements: OEMs are required to report tailpipe NO₂ concentration and NO₂ increase level if an oxidation catalyst-based aftertreatment system is used, such as DOC, POC, DPF or NAC.
• NH₃ slip limit: No limit for China IV. For China V, NH₃ slip limit is 25 ppm (peak) and 10 ppm (cycle average).

Implementation dates for the standards are listed in Table 2. The dates generally refer to new type approvals—first registration of existing vehicle models is typically allowed for one more year.

Emission durability requirements, including the engine useful life and the minimum aftertreatment testing periods, are shown in Table 3. The aftertreatment periods according to HJ 438-2008 are mandatory for type approval and production conformity, while GB 20890-2007 provides a guideline to conduct aftertreatment durability testing during product development.

The GB 20890-2007 standard recommends that aftertreatment testing be conducted on-vehicle, over the China Heavy-Duty Durability Cycle—Vehicle (C-HDD-V). Alternatively, an engine based durability test can be conducted over the China Heavy-Duty Durability Cycle—Engine (C-HDD-E).