ISO 4106:2012

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
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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 engin
...