Overview
ISO 4106:2012 - "Motorcycles - Engine test code - Net power" is an international standard specifying test methods for measuring and presenting the net power, net torque and specific fuel consumption of motorcycle engines. The fourth edition consolidates previously cross-referenced material so ISO 4106 can be used as a stand‑alone test code for reciprocating internal combustion engines (spark‑ignition or compression‑ignition) and rotary piston engines - naturally aspirated or pressure‑charged - excluding free‑piston engines. Annex A contains particular requirements for compression‑ignition engines.
Key topics and technical requirements
- Scope and definitions: Clear definitions of net power, corrected net power, net torque, specific fuel consumption and auxiliaries for test conditions.
- Standard reference conditions: corrections are referenced to p = 100 kPa, t = 298 K, relative humidity = 30 %.
- Test procedures: Full‑throttle runs with stabilized operating conditions; presentation of power and fuel‑consumption curves as functions of engine speed.
- Test bench setup and auxiliaries: Guidance on installing inlet systems, exhaust, fuel supply and injection equipment, cooling (liquid/air), electrical systems, pressure‑charging and anti‑pollution devices so the engine is tested in representative in‑service configuration.
- Measuring equipment accuracy: Minimum instrument accuracies given for reliable results:
- Torque: ±1% (±2% below 50% max power)
- Engine speed: ±0.5%
- Fuel flow: ±1%
- Temperatures (fuel, inlet air): ±1 K
- Barometric pressure: ±70 Pa
- Exhaust back pressure: ±25 Pa
- Humidity: ±5% RH
- Calculations and corrections: Methods for calculating measured and corrected net torque/power and fuel consumption under standard reference conditions.
- Reporting: Required content of test reports and statement of results for verification of declared engine values.
Applications and who uses it
ISO 4106 is used to:
- Verify declared engine net power and fuel consumption in technical documentation and type approval.
- Generate power curves and specific fuel consumption maps for engine development and calibration.
- Support laboratory certification, regulatory compliance and comparative testing for motorcycle manufacturers, engine designers, test laboratories, homologation authorities and R&D teams.
Keywords: motorcycle engine test code, net power measurement, dynamometer testing, specific fuel consumption.
Related standards
- ISO 3833 (vehicle types and definitions)
- ISO 15550 (general engine power measurement requirements - historically cross‑referenced)
- ISO 2710‑1 (internal combustion engine vocabulary)
ISO 4106:2012 provides the practical, repeatable procedures and accuracy requirements needed for reliable motorcycle engine net power and efficiency evaluation.
