Overview
ISO 16185:2000 - Road vehicles - Engine families for certification of heavy‑duty vehicles - Exhaust emissions defines how manufacturers may group heavy‑duty road vehicle engines into engine families for exhaust emission certification. The standard applies only to heavy‑duty road vehicle engines (not mopeds, motorcycles, passenger cars or non‑road engines) and establishes membership criteria, parameters to differentiate families, and the procedure to select a parent engine for type‑approval emission testing. The family concept reduces the number of tests required for certification and supports harmonized approaches such as worldwide heavy‑duty certification (WHDC).
Key topics and requirements
- Engine family concept - Engines of the same manufacturer with similar regulated exhaust emission characteristics (gaseous, particulate and smoke) may be grouped into an engine family for certification.
- Core parameters that define a family include:
- Combustion cycle (2‑stroke, 4‑stroke, rotary, etc.)
- Cylinder configuration and relative positions
- Main cooling medium (air, water, oil)
- Unit cylinder displacement thresholds and allowable spread (guidance provided for engines around 0.75 dm3)
- Method of air aspiration (naturally aspirated, pressure charged, charge‑air cooled)
- Fuel type (diesel, gasoline, gaseous fuels, DME, hydrogen, alcohols, etc.)
- Combustion chamber and ignition type (spark or compression)
- Valve/porting layout and number of valves per cylinder
- Fuel supply system (common rail, unit injector, pumps, carburettors, mixing units)
- Electronic control strategies (presence of ECU; timing, injection pressure, multiple injection, VGT, EGR)
- After‑treatment systems (oxidation catalysts, DeNOx, particulate traps - classified as controlled vs non‑controlled)
- Parent engine selection - Procedures differ for compression‑ignition and spark‑ignition engines:
- Compression‑ignition: primary criterion is highest fuel delivery per stroke at declared maximum torque speed (secondary: highest fuel delivery per stroke at rated speed).
- Spark‑ignition: primary criterion is largest displacement; tie‑breakers include fuel delivery per stroke at rated power speed, most advanced spark timing and lowest EGR rate.
- Manufacturer responsibilities - Identify interactions and special devices that may affect emissions, provide technical justification for family groupings, and notify authorities. Manufacturers may define smaller families if desired.
Applications and users
- Intended for engine manufacturers, certification authorities, test laboratories and regulatory bodies involved in heavy‑duty vehicle exhaust emissions certification.
- Practical uses: reducing certification test burden, defining representative (parent) engines for type approval, and providing a documented basis for engine family grouping in regulatory submissions.
Related standards
- Normative reference: ISO 8178‑7:1996 (engine family determination within broader engine emission measurement framework).
- Relevant to UN/ECE/GRPE work and initiatives toward worldwide heavy‑duty certification (WHDC).