ISO 4106:2012

Motorcycles - Engine test code - Net power

This International Standard specifies methods for evaluating the performance of engines designed for motorcycles as defined in ISO 3833, in particular with a view to the presentation of power curves and specific fuel consumption at full load as a function of engine speed, for net power assessment. It is applicable to reciprocating internal combustion engines (spark-ignition or compression-ignition) - excluding free-piston engines - and rotary piston engines, either naturally aspirated or pressure-charged and equipped with either mechanical pressure-charger or turbocharger. Particular specifications for the test of compression-ignition engines are specified in Annex A.

Motocycles — Code d'essai des moteurs — Puissance nette

General Information

• Status: Published
• Publication Date: 20-May-2012
• ICS: 43.140 - Motorcycles and mopeds
• Technical Committee: ISO/TC 22/SC 38 - Motorcycles and mopeds
• Drafting Committee: ISO/TC 22/SC 38 - Motorcycles and mopeds
• Current Stage: 9092 - International Standard to be revised
• Start Date: 27-Jun-2024
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 4106:2004 - Motorcycles - Engine test code - Net power
• Effective Date: 10-Oct-2009

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4106
Fourth edition
2012-06-01
Motorcycles — Engine test code — Net
power
Motocycles — Code d’essai des moteurs — Puissance nette
Reference number
©
ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Standard reference conditions . 2
6 Tests . 3
6.1 General . 3
6.2 Measuring equipment and instrument accuracy . 3
6.3 Setting and test conditions . 3
6.4 Test procedure . 7
7 Torque, power and specific fuel consumption . 8
7.1 Calculation of measured torque, measured power and specific fuel consumption . 8
7.2 Net torque and net power . 8
7.3 Corrected net torque and corrected net power . 9
8 Test report .10
8.1 General .10
8.2 The description of test report .10
8.3 Statement of results .14
Annex A (normative) Test method for compression-ignition engines .17
Bibliography .24
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 4106 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 22, Motorcycles.
This fourth edition cancels and replaces the third edition (ISO 4106:2004), which has been technically revised.
iv © ISO 2012 – All rights reserved

Introduction
The third edition of ISO 4106 (ISO 4106:2004) has many cross-references to ISO 15550, which contains
the requirements that are common to all engine applications. Consequently, users of ISO 4106:2004 always
have to refer to ISO 4106 and ISO 15550 simultaneously in order to comprehend the full test procedures for
motorcycles. In this fourth edition, all the necessary components are described in the text rather than referring
to ISO 15550 in order to avoid such inconveniences, and some technical and editorial modifications have also
been made for refinement.
ISO 4106 can now be used as a stand-alone International Standard for engine net power measurement of motorcycles.
INTERNATIONAL STANDARD ISO 4106:2012(E)
Motorcycles — Engine test code — Net power
1 Scope
This International Standard specifies methods for evaluating the performance of engines designed for
motorcycles as defined in ISO 3833, in particular with a view to the presentation of power curves and specific
fuel consumption at full load as a function of engine speed, for net power assessment. It is applicable to
reciprocating internal combustion engines (spark-ignition or compression-ignition) — excluding free-piston
engines — and rotary piston engines, either naturally aspirated or pressure-charged and equipped with either
mechanical pressure-charger or turbocharger. Particular specifications for the test of compression-ignition
engines are specified in Annex A.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 2710-1, Reciprocating internal combustion engines ― Vocabulary ― Part 1: Terms for engine design
and operation
ISO 3833, Road vehicles ― Types ― Terms and definitions
ISO 15550, Internal combustion engines ― Determination and method for the measurement of engine power ―
General requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2710-1, ISO 15550 and the following apply.
3.1
net power
power obtained on a test bed at the end of the crankshaft or its equivalent at the corresponding engine speed
with the equipment and auxiliaries listed in 6.3.1
3.2
corrected net power
net power corrected under the standard reference conditions
3.3
net torque
torque transmitted on a test bed at the end of the crankshaft or its equivalent at the corresponding engine
speed with the equipment and auxiliaries listed in 6.3.1
3.4
corrected net torque
net torque corrected under the standard reference conditions
3.5
specific fuel consumption
amount of fuel consumed by an engine per unit of power and time
NOTE The amount of the lubricants for two-stroke cycle engines is excluded.
3.6
auxiliaries
equipment and devices necessary to make the engine acceptable for service in the intended application
4 Symbols
For the purposes of this document, the symbols given in Table 1 apply.
Table 1 — Symbols
Symbol Designation Unit
b Specific fuel consumption g/(kW·h)
e
p Ambient dry air barometric pressure during the test kPa
d
p Standard reference total barometric pressure kPa
r
p Standard reference saturated water vapour pressure kPa
sr
p Ambient saturated water vapour pressure during the test kPa
sy
p Ambient total barometric pressure during the test kPa
y
P Measured power kW
P Corrected net power kW
o
P Net power kW
y
T Measured torque N·m
T Corrected net torque N·m
o
T Net torque N·m
y
t Standard reference ambient air temperature K
r
t Engine inlet air temperature during the test K
y
α Correction factor for ambient test conditions —
a
α Correction factor for efficiency of the transmission —
m
η Efficiency of each element constituting the transmission —
i
Efficiency of the transmission which is located between the crankshaft and the
η —
t
measurement point
φ Standard reference relative humidity %
r
φ Ambient relative humidity during the test %
y
5 Standard reference conditions
For the purpose of determining the power and fuel consumption of an engine, the following standard reference
conditions shall be used:
— standard reference total barometric pressure: p = 100 kPa;
r
— standard reference air temperature: t = 298 K;
r
— standard reference relative humidity: φ = 30 %.
r
NOTE A relative humidity of 30 % at a temperature of 298 K corresponds to a water pressure of 1 kPa. The
corresponding dry barometric pressure is 99 kPa.
2 © ISO 2012 – All rights reserved

6 Tests
6.1 General
This test method is used for verifying the net power of an engine type with the declared values. It presents
engine performance at full power/torque as a function of engine speed by generating curves of corrected net
torque, corrected net power and specific fuel consumption.
6.2 Measuring equipment and instrument accuracy
6.2.1 Torque
The dynamometer torque-measuring system shall have an accuracy of ± 1 % in the range of scale values
required for the test. The torque-measuring system shall be calibrated to take into account friction losses. The
accuracy may be ± 2 % for measurements carried out at a power less than 50 % of maximum power.
6.2.2 Engine speed
The engine-speed measuring system shall have an accuracy of ± 0,5 %.
6.2.3 Fuel flow
The fuel-flow measuring system shall have an accuracy of ± 1 %.
6.2.4 Fuel temperature
The fuel-temperature measuring system shall have an accuracy of ± 1 K.
6.2.5 Engine inlet air temperature
The air-temperature measuring system shall have an accuracy of ± 1 K.
6.2.6 Barometric pressure
The barometric-pressure measuring system shall have an accuracy of ± 70 Pa.
6.2.7 Back pressure in exhaust system
The system used to measure the back pressure (differential pressure) in the exhaust system shall have an
accuracy of ± 25 Pa.
6.2.8 Test room humidity
The test-room-humidity measuring system shall have an accuracy of ± 5% in relative humidity.
NOTE In the test atmospheric conditions specified in 6.3.3, the worst relative humidity measurement accuracy of
± 5 % corresponds to a wet and dry bulb thermometer measurement accuracy of ± 0,5 K. In the worst case, it is estimated
that an accuracy of ± 0,5 K in a wet and dry bulb thermometer measurement would have an effect of approximately ± 0,3 %
on the net power measuring result.
6.3 Setting and test conditions
6.3.1 Equipment and auxiliaries
During the test, if the equipment and auxiliaries specified in Table 2 are the standard productions, they shall be
installed on the test bench as far as possible in the same position and in the same condition as in the intended
application. The equipment and auxiliaries for the test of compression-ignition engines are listed in Annex A.
Table 2 — Equipment and auxiliaries to be installed for the test to determine engine power
No. Equipment and auxiliaries
Inlet manifold
Crankcase emission control system
Control devices for dual induction
Electronic control system
1 Inlet system Air flow meter
a
Air inlet ductwork
a
Air filter
a
Inlet silencer
a
Speed-limiting device
2 Induction-heating device of inlet manifold
Exhaust purifier
Exhaust manifold
Pressure-charging device
b
3 Exhaust system Connecting pipes
b
Silencer
b
Tail pipe
Electronic control system
c
Fuel supply pump
Carburettor
Electronic control system
4 Fuel supply system
Gaseous fuel pressure reducer
Gaseous fuel evaporator
Gaseous fuel mixer
Prefilter
Filter
Fuel injection pump
5 Fuel injection equipment High-pressure pipes
Injector
Air inlet valve
Electronic control system
d
Radiator
de
Fan
d
6 Liquid-cooling equipment Fan cowl
d
Water pump
df
Thermostat
d
Cowl
de
7 Air-cooling equipment Fan or blower
Temperature-regulating device
4 © ISO 2012 – All rights reserved

Table 2 (continued)
No. Equipment and auxiliaries
g
Generator
g
Battery
Spark distribution system
8 Electrical equipment Coil or coils
Wiring
Spark-plugs
h
Electronic control system
Compressor driven directly by the engine and/or by the exhaust gases
i
Boost control
Pressure-charging
dej
equipment
Charge air cooler
Coolant pump or fan (engine-driven)
k
10 Anti-pollution device
11 Lubricating oil pump
12 Oil cooler
a
Except in the case where there is a risk of the system having a noticeable influence upon engine power, where the equivalents
may be used. In this case, a check shall be made to ascertain that inlet depression does not differ by more than 100 Pa from the limit
specified by the manufacturer for a clean air filter.
b
If it is impracticable to fit the standard exhaust system, a system permitting the normal engine running characteristics in accordance
with the manufacturer’s specification shall be fitted for the test. In particular, in the test laboratory, the exhaust extraction system at the
point where the test bench exhaust system is connected shall not create a pressure differing from the atmospheric pressure by more
than ± 740 Pa at the exhaust extraction duct, with the engine in operation, unless the manufacturer has specifically prescribed the back
pressure prior to the test, in which case the lower of the two pressures shall be used.
c
If necessary, the fuel feed pressure may be adjusted to reproduce the fuel pressures existing in the particular engine application
(particularly when a “fuel return” system, for example to tank or filter, is used).
d
The radiator, fan, fan cowl, water pump, thermostat and cowl shall be located on the test bed in the same relative positions that
they are to occupy on the vehicle or machine. The cooling liquid circulation shall only be operated by the engine water pump. Cooling
of the liquid may be provided either by the engine radiator or by an external circuit, provided that the pressure loss of this circuit and the
pressure at the pump inlet remain substantially the same as those of the engine cooling system. The radiator shutter, if incorporated,
shall be set in the open position.
Where the fan, radiator and cowl system cannot conveniently be fitted to the engine, the power absorbed by the fan when separately
mounted in its correct position in relation to the radiator and cowl (if used) shall be determined at the speeds corresponding to the
engine speeds used for measurement of the engine power either by calculation from standard characteristics or by practical tests. This
power, corrected to the standard atmospheric conditions defined in Clause 5, shall be deducted from the corrected power.
e
Where a disconnectable or progressive fan or blower is incorporated, the test shall be performed with the fan or blower
disconnected or with the progressive fan running at maximum slip.
f
The thermostat may be fixed in the fully open position.
g
The electrical power of the generator shall be the minimum. It shall be limited to that necessary for operation of accessories which
are indispensable for engine operation. If the connection of a battery is necessary, a fully charged battery in good condition shall be
used.
h
The spark advance shall be representative of in-use conditions established with the minimum octane fuel recommended by the
manufacturer.
i
For engines equipped with variable boost as a function of charge or inlet air temperature, octane rating and/or engine speed,
the boost pressure shall be representative of in-vehicle conditions established with the minimum octane fuel as recommended by the
manufacturer.
j
Charge air-cooled engines shall be tested with the charge air-cooling system operating, whether this system is liquid- or air-cooled.
If the engine manufacturer prefers, a test bed system may replace an air-cooled cooler. In either case the measurement of power at
each speed shall be made with the pressure drop and temperature drop of the engine air across the charge air cooler in the test bed
the same as those specified by the manufacturer for the system on the complete vehicle.
k
These may include, for example, Exhaust Gas Recirculation (EGR) system, catalytic converter, secondary air-supply, fuel
evaporation protection systems and crankcase emission control system.
6.3.2 Test conditions
The test conditions shall be as follows. The particular test conditions for test of compression-ignition engines
shall be as specified in Annex A.
a) The power test shall consist of a run at full throttle, the engine being equipped with equipment and
auxiliaries as specified in 6.3.1.
b) The engine speed during a test run shall not deviate from the selected speed by more than ± 1 %.
c) Performance data shall be obtained under stabilized operating conditions in accordance with the
manufacturer’s specifications, with an adequate fresh-air supply to the engine.
Before the test, the engine shall have been run-in in accordance with the manufacturer’s recommendations.
Test conditions such as inlet air temperature shall be selected to be as near to the standard reference
conditions (see Clause 5) as possible in order to minimize the magnitude of the correction factor.
d) No data shall be taken until torque, engine speed and temperatures have been maintained substantially
constant as specified by the manufacturer.
If the constant operating conditions (torque, engine speed and temperatures) are not specified by the
manufacturer, no data shall be taken until the engine speed has been maintained within the limits specified
in 6.3.2 b). Each measurement period shall be equal for every measurement.
e) Data on the observed brake load, the fuel consumption and the engine inlet air temperature shall be taken
virtually simultaneously and shall, in each case, be the average of two consecutive stabilized readings for
which the brake load and fuel consumption do not vary by more than 2 %.
No adjustment shall be made to the engine between these readings.
f) A measurement time of not less than 10 s shall be used when measuring engine speed and fuel consumption
with an automatically synchronized counter-timer combination.
g) For liquid-cooled engines, the temperature of the coolant at the outlet from the engine shall be kept
within ± 5 K from the upper thermostatically controlled temperature specified by the manufacturer. If no
temperature is specified by the manufacturer, the temperature shall be 353 K ± 5 K.
For air-cooled engines, the temperature at a point indicated by the manufacturer shall be kept within K
−20
of the maximum value specified by the manufacturer for the reference conditions.
If no temperature is specified by the manufacturer, the temperature of the ignition spark-plug washer shall
be 523 K or less. For multi-cylinder engines, it is permissible to measure the ignition spark-plug washer
temperature at only one representative cylinder.
h) The fuel temperature shall be measured as near as possible to the inlet of the carburettor or fuel injector
manifold assembly. Fuel temperature shall be maintained within ± 5 K of the temperature specified by the
manufacturer. However, the minimum test fuel temperature allowed shall be the ambient air temperature.
If the test fuel temperature is not specified by the manufacturer, it shall be 298 K ± 20 K.
i) The lubricating oil temperature measured in the oil sump or at the oil cooler outlet, if fitted, shall be
maintained within the limits established by the engine manufacturer.
j) Engine inlet air temperature shall be measured within 0,15 m of the point of entry to the air cleaner, or, if no
air cleaner is used, within 0,15 m of the air inlet horn. The inlet depression measurement shall be made at
the same point.
The thermometer or thermocouple shall be shielded from fuel spray-back and radiant heat and located
directly in the air stream. A sufficient number of locations shall be used to give a representative average
of the inlet temperature.
k) The exhaust temperature shall be measured at a point in the exhaust pipe(s) adjacent to the outlet flange(s)
of the exhaust manifold(s) or ports.
6 © ISO 2012 – All rights reserved

l) In cases of type approval (certification) or acceptance test, the selection of fuel for power test shall be
agreed by the parties involved and be selected in accordance with the requirements of Table 3. In the case
of other tests, an appropriate fuel for the test can be used.
Unleaded gasoline shall be used for the engine equipped with the catalyst. Specifications for test fuels in
8.2.2 e) shall be reported in cases of type approval (certification) or acceptance test. For other types of
test, at least the following fuel information shall be reported.
1) make and name;
2) octane number RON or MON;
3) relative density at 288 K, in g/cm ;
4) lower calorific value, in kJ/kg;
5) applicable fuel standard(s).
In case of using commercial fuels, it is permitted to only report the following information:
— make and name;
— grade;
— applicable fuel standard(s).
m) Data to be recorded shall be those indicated in 8.3.
Table 3 — Test fuels
Test purpose Interested parties Fuel selection
Reference fuel, if one is defined
Type approval Certification body, manufacturer or
(certification) supplier
Commercial fuel if no reference fuel is defined
Manufacturer or supplier
Acceptance test Commercial fuel as specified by the manufacturer
Customer or inspector
6.3.3 Test atmospheric conditions
The atmospheric conditions during the test shall be within the range given below.
a) Engine inlet air temperature, in kelvin, 288≤≤t 308 .
y
b) Dry pressure, in kilopascal, 90≤≤p 110 .
d
NOTE pp=−φ p .
dy ysy
6.4 Test procedure
Measurements shall be taken at a sufficient number of engine speeds to completely define the torque and
power curve between the lowest and the highest engine speeds recommended by the manufacturer. The
speed range shall include the point at which the engine produces its maximum torque and power. Data shall be
taken incrementally from the lowest to the highest engine speeds re
...