Overview
ISO 1585:2020 - Road vehicles - Engine test code - Net power specifies a standardized method for testing internal combustion engines intended for automotive use to determine net power and related performance characteristics. The standard covers presenting power curves and specific fuel consumption at full load as a function of engine speed. It applies to reciprocating (spark-ignition and compression-ignition) and rotary piston engines used in passenger cars, trucks and other road vehicles - excluding motorcycles, mopeds and agricultural tractors. Both naturally aspirated and pressure‑charged (supercharged or turbocharged) engines are included.
Key topics and technical requirements
ISO 1585:2020 organizes practical test methodology and reporting requirements around a number of technical topics:
- Accuracy of measuring equipment: requirements for torque, engine speed, fuel flow, temperatures, pressures and exhaust back‑pressure measurement accuracy.
- Test setup and auxiliaries: which engine-driven accessories to fit or remove during net power assessment and settings for starting and cooling systems.
- Test conditions and procedures: standardized environmental and operational conditions for recording power and fuel-consumption curves.
- Power correction factors: definitions and procedures to correct measured power for different atmospheric conditions, including provisions for turbocharged engines with ambient-compensation systems.
- Smoke measurement and correction: procedures and correction factors for smoke (light absorption) for compression‑ignition engines.
- Reporting and verification: required test report content, declaration formats, tolerances on declared net power, torque and specific fuel consumption.
Notable updates in the 2020 edition: clarified air‑induction system definition, a requirement addressing particulate filter restriction, active thermal-management settings for cooling systems, and a new correction factor for certain turbocharged systems.
Practical applications and who uses this standard
ISO 1585:2020 is used to produce repeatable, comparable measurements of engine net power and specific fuel consumption. Typical users include:
- Engine and vehicle manufacturers (OEMs) validating engine performance
- Independent test laboratories and certification bodies conducting power characterization
- R&D and powertrain engineering teams developing engines, turbochargers, and cooling systems
- Regulatory authorities and compliance testers who need standardized measurement protocols
- Suppliers of engine measurement equipment and dynamometers
Related standards
Normative references cited in ISO 1585:2020 include ISO documents on engine vocabulary and fuel injection equipment, such as:
Using ISO 1585:2020 helps ensure consistent, industry‑recognized engine testing, enabling accurate published power ratings, reliable fuel‑consumption curves, and defensible verification against declared performance.
