ISO 4164:2012

Overview

ISO 4164:2012 - Mopeds - Engine test code - Net power specifies standardized methods to evaluate the performance of moped engines (as defined in ISO 3833). The standard focuses on producing power curves, specific fuel consumption at full load vs. engine speed, and determining net power and net torque for spark‑ignition reciprocating and rotary piston engines (naturally aspirated or pressure‑charged). It is intended for engine test beds and reporting of corrected net power under defined standard reference conditions.

Key topics and technical requirements

• Scope and applicability
  • Applies to moped engines (reciprocating internal combustion and rotary piston) but excludes free‑piston engines.
• Standard reference conditions
  • Reference barometric pressure, temperature and humidity are defined for correction to a common baseline when reporting net power.
• Measurements and accuracy
  • Torque dynamometer accuracy: ±1% (±2% for <50% of maximum power).
  • Engine speed accuracy: ±0.5%.
  • Fuel flow accuracy: ±2%; fuel temperature ±1 K; inlet air temperature ±1 K.
  • Barometric pressure accuracy: ±70 Pa; exhaust back pressure ±25 Pa; test-room humidity ±5% RH.
• Test setup - equipment and auxiliaries
  • Requires fitting inlet/exhaust systems, fuel supply/injection, cooling (liquid/air), electronic controls and other auxiliaries in the same relative positions as in intended service where practical.
  • Specifies handling of substitutes (e.g., equivalent inlet or exhaust parts) and limits for inlet depression and exhaust back pressure.
• Data and calculations
  • Defines measured vs. net vs. corrected net torque/power and methods to calculate specific fuel consumption (fuel mass per unit power and time).
• Test procedures and reporting
  • Describes test procedures, instrumentation, correction factors and the required content of the test report for reproducible certification and comparison.

Practical applications and intended users

ISO 4164:2012 is used by:

• Engine and moped manufacturers for type‑approval, performance validation and specification of rated power.
• Test laboratories and dynamometer facilities to conduct repeatable net power tests and generate certified power/sfc curves.
• Regulatory bodies and certification agencies assessing compliance with declared power figures.
• R&D and powertrain engineers comparing designs, calibrations, turbocharging and auxiliaries effects on net power and fuel consumption.
• Component suppliers (turbochargers, fuel systems, ignition/electronics) validating real‑world influence on engine output.

Related standards

• ISO 2710‑1 (engine vocabulary)
• ISO 3833 (road vehicle definitions)
• ISO 15550 (general engine power measurement requirements)

For full test procedures, equations and reporting templates consult the complete ISO 4164:2012 document available from ISO or your national standards body.