ISO 4164:2012

INTERNATIONAL ISO
STANDARD 4164
Second edition
2012-09-15
Mopeds — Engine test code — Net
power
Cyclomoteurs — Code d’essai des moteurs — Puissance nette
Reference number
©
ISO 2012
© ISO 2012
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ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
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 .10
7 Torque, power and specific fuel consumption .10
7.1 Calculation of measured torque, measured power and specific fuel consumption .10
7.2 Net torque and net power .11
7.3 Corrected net torque and corrected net power .12
8 Test report .13
8.1 General .13
8.2 The description of test report .13
8.3 Statement of results .16
Bibliography .19
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 4164 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 23, Mopeds.
This second edition cancels and replaces the first edition (ISO 4164:1978), which has been technically revised.
iv © ISO 2012 – All rights reserved

INTERNATIONAL STANDARD ISO 4164:2012(E)
Mopeds — Engine test code — Net power
1 Scope
This International Standard specifies methods for evaluating the performance of engines designed for
mopeds 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), excluding free-piston engines, and rotary
piston engines, either naturally aspirated or pressure-charged and equipped with either mechanical
pressure-charger or turbocharger.
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-stoke cycle engines is excluded.
3.6
auxiliaries
equipment and devices necessary to make the engine acceptable for service in the intended application.
4 Symbols
The symbols used in this International Standard are given in Table 1.
Table 1 — Symbols
Symbols 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 Nm
T Corrected net torque Nm
o
T Net torque Nm
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
η -
t
crankshaft and the 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: pr = 100 kPa;
— Standard reference air temperature: tr = 298 K;
— Standard reference relative humidity: ϕr = 30 %;
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 ± 2 %.
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 specified test atmospheric conditions 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 accuracy of ± 0,5 K in a wet and dry bulb thermometer measurement would give the
influence 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 as the same condition as
in the intended application.
Table 2 — Equipment and auxiliaries to be installed for the test to determine engine power
No. Equipment and auxiliaries
1 Inlet system:
Inlet manifold
Crankcase emission control system
Control devices for dual induction
Electronic control system
Air flow meter
Air inlet ductwork
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 ascer-
tain that inlet depression does not differ by more than 100 Pa from the limit specified by the
manufacturer for a clean air filter.
Air filter
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 ascer-
tain that inlet depression does not differ by more than 100 Pa from the limit specified by the
manufacturer for a clean air filter.
Inlet silencer
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 ascer-
tain that inlet depression does not differ by more than 100 Pa from the limit specified by the
manufacturer for a clean air filter.
Speed-limiting device
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 ascer-
tain that inlet depression does not differ by more than 100 Pa from the limit specified by the
manufacturer for a clean air filter.
2 Induction-heating device of inlet manifold
4 © ISO 2012 – All rights reserved

Table 2 (continued)
No. Equipment and auxiliaries
3 Exhaust system:
Exhaust purifier
Exhaust manifold
Pressure-charging device
Connecting pipes
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
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