ISO 1585:2020

Road vehicles — Engine test code — Net power

This document specifies a method for testing engines designed for automotive vehicles. It applies to the evaluation of their performance with a view, in particular to presenting curves of power and specific fuel consumption at full load as a function of engine speed. It applies only to net power assessment. This document concerns internal combustion engines used for propulsion of passenger cars, trucks and other motor vehicles, excluding motorcycles, mopeds and agricultural tractors normally travelling on roads, and included in one of the following categories: — reciprocating internal combustion engines (spark-ignition or compression-ignition) but excluding free piston engines; — rotary piston engines. These engines can be naturally aspirated or pressure-charged, either using a mechanical supercharger or turbocharger.

Véhicules routiers — Code d'essai des moteurs — Puissance nette

General Information

• Status: Published
• Publication Date: 23-Jul-2020
• ICS: 43.060.01 - Internal combustion engines for road vehicles in general
• Technical Committee: ISO/TC 22/SC 34 - Propulsion, powertrain and powertrain fluids
• Drafting Committee: ISO/TC 22/SC 34/WG 5 - Engine test code
• Current Stage: 6060 - International Standard published
• Start Date: 24-Jul-2020
• Due Date: 14-Jan-2020
• Completion Date: 24-Jul-2020

Relations

• Revises: ISO 1585:1992 - Road vehicles — Engine test code — Net power
• Effective Date: 04-Nov-2015

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 1585
Fourth edition
2020-07
Road vehicles — Engine test code —
Net power
Véhicules routiers — Code d'essai des moteurs — Puissance nette
Reference number
ISO 1585:2020(E)
©
ISO 2020

---------------------- Page: 1 ----------------------
ISO 1585:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 1585:2020(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Accuracy of measuring equipment and instruments . 2
4.1 Torque . 2
4.2 Engine speed (rotational frequency) . 2
4.3 Fuel flow . 2
4.4 Fuel temperature. 2
4.5 Air temperature . 2
4.6 Barometric pressure . 2
4.7 Back pressure in exhaust system . 2
4.8 Depression in inlet system . 3
4.9 Absolute pressure in inlet duct . 3
5 Tests . 6
5.1 Auxiliaries . 6
5.1.1 Auxiliaries to be fitted . 6
5.1.2 Auxiliaries to be removed . 6
5.1.3 Compression-ignition engine starting auxiliaries . 6
5.2 Setting conditions . 6
5.3 Test conditions . 7
5.4 Test procedure . 8
5.5 Data to be recorded . 8
6 Power correction factors . 9
6.1 Definition of factor α for power correction . 9
6.2 Atmospheric conditions . 9
6.2.1 Reference atmospheric conditions . 9
6.2.2 Test atmospheric conditions . 9
6.3 Determination of power correction factors . 9
6.3.1 Naturally aspirated and pressure-charged spark-ignition engines — Factor α .10
a
6.3.2 Compression-ignition engines — Factor α . .10
c
6.3.3 Turbocharged engine with a system compensating the ambient conditions .12
6.3.4 Other types of engine .12
7 Measurement of and correction for smoke value for compression-ignition engines .12
7.1 Correction factor for light absorption coefficient of smoke .12
7.2 Determination of correction factor for light absorption coefficient of smoke .13
7.3 Limits of application.13
8 Test report .13
8.1 Compression-ignition engines — Essential characteristics .13
8.1.1 Description of engine .13
8.1.2 Cooling system .14
8.1.3 Temperatures specified by the manufacturer .14
8.1.4 Pressure charger (with/without) (delete where inapplicable) .15
8.1.5 Inlet system .15
8.1.6 Additional smoke control devices (if any, and if not covered by another
heading) . .15
8.1.7 Fuel feed system .16
8.1.8 Valve timing .17
8.1.9 Exhaust system .17
8.1.10 Lubrication system .17
8.1.11 Electrical equipment .17
8.1.12 Other engine-driven equipment .17
© ISO 2020 – All rights reserved iii

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ISO 1585:2020(E)

8.2 Spark-ignition engines — Essential characteristics .17
8.2.1 Description of engine .17
8.2.2 Cooling system .18
8.2.3 Temperature specified by the manufacturer .19
8.2.4 Pressure charger (with/without) (delete where inapplicable) .19
8.2.5 Inlet system .19
8.2.6 Additional anti-pollution devices (if any, and if not covered by another
heading) .20
8.2.7 Fuel feed system .20
8.2.8 Valve timing .20
8.2.9 Ignition system .20
8.2.10 Exhaust system .21
8.2.11 Lubrication system .21
8.2.12 Electrical equipment .22
8.2.13 Other auxiliaries fitted to engine .22
8.3 Test conditions for measuring engine net power .22
8.4 Statement of results as function of engine speed.24
9 Verification of engine performance .25
9.1 Designation .25
9.2 Notation .25
9.2.1 Declared net power and corresponding engine speed (range) .25
9.2.2 Declared net torque and corresponding engine speed (range) .26
9.2.3 Declared specific net fuel consumption and corresponding engine speed
(range) .26
9.3 Tolerances — Declared values .26
9.3.1 Power .26
9.3.2 Torque .27
9.3.3 Specific fuel consumption .27
9.3.4 Numerical tolerances .27
Bibliography .32
iv © ISO 2020 – All rights reserved

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ISO 1585:2020(E)

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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 34,
Propulsion, powertrain and powertrain fluids.
This fourth edition cancels and replaces the third edition (ISO 1585:1992), which has been technically
revised. The main changes compared to the previous edition are as follows:
— the air induction system definition has been updated to clarify included components;
— a requirement for exhaust particulate filter restriction has been added;
— a requirement for engine cooling active thermal management system settings has been added;
— a power correction factor for turbocharged engines with a system compensating the ambient
conditions has been added.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2020 – All rights reserved v

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INTERNATIONAL STANDARD ISO 1585:2020(E)
Road vehicles — Engine test code — Net power
1 Scope
This document specifies a method for testing engines designed for automotive vehicles. It applies to the
evaluation of their performance with a view, in particular to presenting curves of power and specific
fuel consumption at full load as a function of engine speed.
It applies only to net power assessment.
This document concerns internal combustion engines used for propulsion of passenger cars, trucks and
other motor vehicles, excluding motorcycles, mopeds and agricultural tractors normally travelling on
roads, and included in one of the following categories:
— reciprocating internal combustion engines (spark-ignition or compression-ignition) but excluding
free piston engines;
— rotary piston engines.
These engines can be naturally aspirated or pressure-charged, either using a mechanical supercharger
or turbocharger.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 7876-1, Fuel injection equipment — Vocabulary — Part 1: Fuel injection pumps
ISO 7967-1, Reciprocating internal combustion engines — Vocabulary of components and systems — Part 1:
Structure and external covers
ISO 7967-2, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 2: Main running gear
ISO 7967-3, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 3: Valves, camshaft drives and actuating mechanisms
ISO 7967-4, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 4: Pressure charging and air/exhaust gas ducting systems
ISO 7967-5, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 5: Cooling systems
ISO 7967-8, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 8: Starting systems
ISO 11614, Reciprocating internal combustion compression-ignition engines — Apparatus for measurement
of the opacity and for determination of the light absorption coefficient of exhaust gas
© ISO 2020 – All rights reserved 1

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ISO 1585:2020(E)

3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2710-1, ISO 7876-1, ISO 7967-1,
ISO 7967-2, ISO 7967-3, ISO 7967-4, ISO 7967-5 and ISO 7967-8 and the following definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
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 Table 1
Note 1 to entry: If the power measurement can only be carried out with a mounted gearbox, the losses in the
gearbox should be added to the measured power to give the engine power.
3.2
standard production equipment
any equipment provided by the manufacturer for a particular engine application
4 Accuracy of measuring equipment and instruments
4.1 Torque
The dynamometer torque-measuring system shall have an accuracy within ±1 % in the range of scale
values required for the test.
4.2 Engine speed (rotational frequency)
The engine speed (rotational frequency) measuring system shall have an accuracy of ±0,5 %.
4.3 Fuel flow
The fuel flow measuring system shall have an accuracy of ±1 %.
4.4 Fuel temperature
The fuel temperature measuring system shall have an accuracy of ±2 K.
4.5 Air temperature
The air temperature measuring system shall have an accuracy of ±1 K.
4.6 Barometric pressure
The barometric pressure measuring system shall have an accuracy of ±100 Pa.
2
NOTE 1 Pa = 1 N/m .
4.7 Back pressure in exhaust system
The system used to measure the back pressure in the exhaust system shall have an accuracy of ±200 Pa.
The measurement shall be made subject to footnote b of Table 1.
2 © ISO 2020 – All rights reserved

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ISO 1585:2020(E)

4.8 Depression in inlet system
The system used to measure the depression in the inlet system shall have an accuracy of ±50 Pa. The
measurement shall be made subject to footnote a of Table 1.
4.9 Absolute pressure in inlet duct
The system used to measure the absolute pressure in the inlet duct shall have an accuracy of ±2 % of
the measured pressure.
Table 1 — Installation of equipment and auxiliaries during test
No. Equipment and auxiliaries Fitted for net power test
1 Inlet system

Inlet manifold

Crankcase emission control system 

Control devices for dual induction inlet manifold system


Air flow meter Yes, standard production equipment


a
Air inlet ductwork

a

Air filter

a
Inlet silencer


a
Speed-limiting device
2 Induction heating device of inlet manifold Yes, standard production equipment
If possible, to be set in the most
favourable position.
3 Exhaust system
b 
Exhaust purifier(s)

Exhaust manifold


Pressure-charging devices

Yes, standard production equipment

c
Connecting pipes

c 
Silencer

c
Tail pipe


d
Exhaust brake
e
4 Fuel supply pump Yes, standard production equipment
5 Carburation equipment

Carburettor

Electronic control system, air-flow meter, etc. (if fitted)


Equipment for gaseous fuel engines Yes, standard production equipment


Pressure reducer


Evaporator

Mixer
© ISO 2020 – All rights reserved 3

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ISO 1585:2020(E)

Table 1 (continued)
No. Equipment and auxiliaries Fitted for net power test
6 Fuel injection equipment [spark-ignition and compression

ignition (diesel)]


Prefilter

Filter


Pump


High-pressure pipe Yes, standard production equipment


Injector

f
Air inlet valve (if fitted)


Electronic control system, etc. (if fitted)


Governor/control system: automatic full-load stop for

the control depending on atmospheric conditions 
7 Liquid cooling equipment

Radiator

g,h
Fan

Yes, standard production equipment

Fan cowl


Water pump

i
Thermostat or thermal management system
8 Air cooling

Cowl

Yes, standard production equipment

g,h
Fan or blower


Temperature regulating device
9 Electrical or electronic equipment

j
Generator/alternator


Spark distribution system


Coil(s)
Yes, standard production equipment

Wiring


Spark-plugs


Electronic control system including knock sensor/spark

m
retard system
10 Pressure-charging equipment (if fitted)

Compressor driven either directly by the engine,

and/or by the exhaust gases


n
Boost control Yes, standard production equipment


g,h,k
Charge-air-cooler

Coolant pump or fan(engine-driven) 

Coolant flow control devices (if fitted)
11 Auxiliary test bed fan Yes, if necessary
l
12 Anti-pollution devices Yes, standard production equipment
4 © ISO 2020 – All rights reserved

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ISO 1585:2020(E)

Table 1 (continued)
No. Equipment and auxiliaries Fitted for net power test
a
  The air induction system begins where the air enters the system from atmosphere. Except when there is a risk
of the system having a noticeable influence upon engine power, an equivalent system may be used. In this case, a
check should 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
 For the case of an exhaust particulate filter, the filter or equivalent restriction shall represent the clean state.
c
 Except when there is a risk of the system having a noticeable influence upon engine power, an equivalent
system may be used. In this case, a check should be made to ascertain that the backpressure in the engine ex-
haust system does not differ by more than 1 000 Pa from that specified by the manufacturer.
d
  If an exhaust brake is incorporated in the engine, the throttle valve shall be fixed fully open.
e
The fuel feed pressure may be adjusted, if necessary, to reproduce the inlet pump pressure conditions consist-
ent with the particular engine application (particularly where a "fuel return" system, e.g. to tank or filter, is used).
f
  The air inlet valve is the control valve for the pneumatic governor of the injection pump. The governor of the
fuel injection equipment may contain other devices which may affect the amount of fuel injected.
g
  The radiator, fan, fan cowl, water pump and thermostat shall be located on the test bed in the same relative
positions that they will occupy on the vehicle. The cooling liquid circulation shall be operated by the engine
water pump only.
Cooling of the liquid may be produced 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 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 6.2 shall be deducted from the corrected power.
h
  Where a separate disconnectable or progressive fan or blower is incorporated, the test shall be made with
the disconnectable fan or blower disconnected or with the progressive fan running at the maximum slip.
i
  The thermostat may be fixed in the fully open position. For the case of an active thermal management sys-
tem, control settings shall be representative of full load operation.
j
  Minimum power of the generator/alternator: the power of the generator/alternator shall be limited to that
necessary for the operation of accessories which are indispensable for engine operation. If the connection of a
battery is necessary, a fully charged battery in good order shall be used.
k
  Charge-air-cooled engines shall be tested complete with charge-air-cooling whether liquid or air-cooled
but if the engine manufacturer prefers, a test bed system may replace the 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.
If a test bed system is used on a compression-ignition engine without a wastegate, or with the wastegate not
operating, the correction factor given in 6.3.2.1 b) is to be used. If a wastegate is both fitted and operating,
then the correction factor in 6.3.2.1 a) is to be used.
l
They may include for example EGR system, catalytic converter, particulate filter, thermal reactor, secondary
air supply system and fuel evaporating protecting system.
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 1585
ISO/TC 22/SC 34
Road vehicles — Engine test code —
Secretariat: ANSI
Net power
Voting begins on:
2020­03­23
Véhicules routiers — Code d'essai des moteurs — Puissance nette
Voting terminates on:
2020­05­18
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 1585:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020

---------------------- Page: 1 ----------------------
ISO/FDIS 1585:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH­1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 1585:2020(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Accuracy of measuring equipment and instruments . 2
4.1 Torque . 2
4.2 Engine speed (rotational frequency) . 2
4.3 Fuel flow . 2
4.4 Fuel temperature. 2
4.5 Air temperature . 2
4.6 Barometric pressure . 2
4.7 Back pressure in exhaust system . 2
4.8 Depression in inlet system . 3
4.9 Absolute pressure in inlet duct . 3
5 Tests . 6
5.1 General . 6
5.1.1 Auxiliaries to be fitted . 6
5.1.2 Auxiliaries to be removed . 6
5.1.3 Compression-ignition engine starting auxiliaries . 6
5.2 Setting conditions . 6
5.3 Test conditions . 7
5.4 Test procedure . 8
5.5 Data to be recorded . 8
6 Power correction factors . 9
6.1 Definition of factor α for power correction . 9
6.2 Atmospheric conditions . 9
6.2.1 Reference atmospheric conditions . 9
6.2.2 Test atmospheric conditions . 9
6.3 Determination of power correction factors . 9
6.3.1 Naturally aspirated and pressure-charged spark-ignition engines — Factor α .10
a
6.3.2 Compression-ignition engines — Factor α . .10
c
6.3.3 Turbocharged engine with a system compensating the ambient conditions .12
6.3.4 Other types of engine .12
7 Measurement of and correction for smoke value for compression-ignition engines .12
7.1 Correction factor for light absorption coefficient of smoke .12
7.2 Determination of correction factor for light absorption coefficient of smoke .13
7.3 Limits of application.13
8 Test report .13
8.1 Compression-ignition engines — Essential characteristics .13
8.1.1 Description of engine .13
8.1.2 Cooling system .14
8.1.3 Temperatures specified by the manufacturer .14
8.1.4 Pressure charger (with/without) (delete where inapplicable) .15
8.1.5 Inlet system .15
8.1.6 Additional smoke control devices (if any, and if not covered by another
heading) . .15
8.1.7 Fuel feed system .16
8.1.8 Valve timing .17
8.1.9 Exhaust system .17
8.1.10 Lubrication system .17
8.1.11 Electrical equipment .17
8.1.12 Other engine-driven equipment .17
© ISO 2020 – All rights reserved iii

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ISO/FDIS 1585:2020(E)

8.2 Spark-ignition engines — Essential characteristics .17
8.2.1 Description of engine .17
8.2.2 Cooling system .18
8.2.3 Temperature specified by the manufacturer .19
8.2.4 Pressure charger (with/without) (delete where inapplicable) .19
8.2.5 Inlet system .19
8.2.6 Additional anti-pollution devices (if any, and if not covered by another
heading) .20
8.2.7 Fuel feed system .20
8.2.8 Valve timing .20
8.2.9 Ignition system .20
8.2.10 Exhaust system .21
8.2.11 Lubrication system .21
8.2.12 Electrical equipment .22
8.2.13 Other auxiliaries fitted to engine .22
8.3 Test conditions for measuring engine net power .22
8.4 Statement of results as function of engine speed.24
9 Verification of engine performance .25
9.1 Designation .25
9.2 Notation .25
9.2.1 Declared net power and corresponding engine speed (range) .25
9.2.2 Declared net torque and corresponding engine speed (range) .26
9.2.3 Declared specific net fuel consumption and corresponding engine speed
(range) .26
9.3 Tolerances — Declared values .26
9.3.1 Power .26
9.3.2 Torque .27
9.3.3 Specific fuel consumption .27
9.3.4 Numerical tolerances .27
Bibliography .32
iv © ISO 2020 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/FDIS 1585:2020(E)

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 non­governmental, 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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 34,
Propulsion, powertrain and powertrain fluids.
This fourth edition cancels and replaces the third edition (ISO 1585:1992), which has been technically
revised. The main changes compared to the previous edition are as follows:
— air induction system definition updated to clarify included components;
— requirement for exhaust particulate filter restriction added;
— requirement for engine cooling active thermal management system settings added;
— power correction factor for turbocharged engines with a system compensating the ambient
conditions added.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 1585:2020(E)
Road vehicles — Engine test code — Net power
1 Scope
This document specifies a method for testing engines designed for automotive vehicles. It applies to the
evaluation of their performance with a view, in particular to presenting curves of power and specific
fuel consumption at full load as a function of engine speed.
It applies only to net power assessment.
This document concerns internal combustion engines used for propulsion of passenger cars, trucks and
other motor vehicles, excluding motorcycles, mopeds and agricultural tractors normally travelling on
roads, and included in one of the following categories:
— reciprocating internal combustion engines (spark-ignition or compression-ignition) but excluding
free piston engines;
— rotary piston engines.
These engines can be naturally aspirated or pressure-charged, either using a mechanical supercharger
or turbocharger.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 2710­1, Reciprocating internal combustion engines — Vocabulary — Part 1: Terms for engine design
and operation
ISO 7876­1, Fuel injection equipment — Vocabulary — Part 1: Fuel injection pumps
ISO 7967­1, Reciprocating internal combustion engines — Vocabulary of components and systems — Part 1:
Structure and external covers
ISO 7967­2, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 2: Main running gear
ISO 7967­3, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 3: Valves, camshaft drives and actuating mechanisms
ISO 7967­4, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 4: Pressure charging and air/exhaust gas ducting systems
ISO 7967­5, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 5: Cooling systems
ISO 7967­8, Reciprocating internal combustion engines — Vocabulary of components and systems —
Part 8: Starting systems
ISO 11614, Reciprocating internal combustion compression-ignition engines — Apparatus for measurement
of the opacity and for determination of the light absorption coefficient of exhaust gas
© ISO 2020 – All rights reserved 1

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ISO/FDIS 1585:2020(E)

3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2710-1, ISO 7876-1, ISO 7967-1,
ISO 7967-2, ISO 7967-3, ISO 7967-4, ISO 7967-5 and ISO 7967-8 and the following definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
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 Table 1
Note 1 to entry: If the power measurement can only be carried out with a mounted gear-box, the losses in the
gear-box should be added to the measured power to give the engine power.
3.2
standard production equipment
any equipment provided by the manufacturer for a particular engine application
4 Accuracy of measuring equipment and instruments
4.1 Torque
The dynamometer torque-measuring system shall have an accuracy within ±1 % in the range of scale
values required for the test.
4.2 Engine speed (rotational frequency)
The engine speed (rotational frequency) measuring system shall have an accuracy of ±0,5 %.
4.3 Fuel flow
The fuel flow measuring system shall have an accuracy of ±1 %.
4.4 Fuel temperature
The fuel temperature measuring system shall have an accuracy of ±2 K.
4.5 Air temperature
The air temperature measuring system shall have an accuracy of ±1 K.
4.6 Barometric pressure
The barometric pressure measuring system shall have an accuracy of ±100 Pa.
2
NOTE 1 Pa = 1 N/m .
4.7 Back pressure in exhaust system
The system used to measure the back pressure in the exhaust system shall have an accuracy of ±200 Pa.
The measurement shall be made subject to footnote b of Table 1.
2 © ISO 2020 – All rights reserved

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ISO/FDIS 1585:2020(E)

4.8 Depression in inlet system
The system used to measure the depression in the inlet system shall have an accuracy of ±50 Pa. The
measurement shall be made subject to footnote a of Table 1.
4.9 Absolute pressure in inlet duct
The system used to measure the absolute pressure in the inlet duct shall have an accuracy of ±2 % of
the measured pressure.
Table 1 — Installation of equipment and auxiliaries during test
No. Equipment and auxiliaries Fitted for net power test
1 Inlet system

Inlet manifold

Crankcase emission control system 

Control devices for dual induction inlet manifold system


Air flow meter Yes, standard production equipment


a
Air inlet ductwork

a

Air filter

a
Inlet silencer


a
Speed­limiting device
2 Induction heating device of inlet manifold Yes, standard production equipment
If possible, to be set in the most
favourable position.
3 Exhaust system
b 
Exhaust purifier(s)

Exhaust manifold


Pressure­charging devices

Yes, standard production equipment

c
Connecting pipes

c 
Silencer

c
Tail pipe


d
Exhaust brake
e
4 Fuel supply pump Yes, standard production equipment
5 Carburation equipment

Carburettor

Electronic control system, air-flow meter, etc. (if fitted)


Equipment for gaseous fuel engines Yes, standard production equipment


Pressure reducer


Evaporator

Mixer
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ISO/FDIS 1585:2020(E)

Table 1 (continued)
No. Equipment and auxiliaries Fitted for net power test
6 Fuel injection equipment [spark-ignition and compression

ignition (diesel)]


Prefilter

Filter


Pump


High­pressure pipe Yes, standard production equipment


Injector

f
Air inlet valve (if fitted)


Electronic control system, etc. (if fitted)


Governor/control system: automatic full-load stop for

the control depending on atmospheric conditions 
7 Liquid cooling equipment

Radiator

g,h
Fan

Yes, standard production equipment

Fan cowl


Water pump

i
Thermostat or thermal management system
8 Air cooling

Cowl

Yes, standard production equipment

g,h
Fan or blower


Temperature regulating device
9 Electrical or electronic equipment

j
Generator/alternator


Spark distribution system


Coil(s)
Yes, standard production equipment

Wiring


Spark­plugs


Electronic control system including knock sensor/spark

m
retard system
10 Pressure-charging equipment (if fitted)

Compressor driven either directly by the engine,

and/or by the exhaust gases


n
Boost control Yes, standard production equipment


g,h,k
Charge­air­cooler

Coolant pump or fan(engine­driven) 

Coolant flow control devices (if fitted)
11 Auxiliary test bed fan Yes, if necessary
l
12 Anti­pollution devices Yes, standard production equipment
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ISO/FDIS 1585:2020(E)

Table 1 (continued)
No. Equipment and auxiliaries Fitted for net power test
a  The air induction system begins where the air enters the system from atmosphere. Except when there is a
risk of the system having a noticeable influence upon engine power, an equivalent system may be used. In this
case, a check should 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  For the case of an exhaust particulate filter, the filter or equivalent restriction shall represent the clean state.
c  Except when there is a risk of the system having a noticeable influence upon engine power, an equivalent
system may be used. In this case, a check should be made to ascertain that the backpressure in the engine ex­
haust system does not differ by more than 1 000 Pa from that specified by the manufacturer.
d
  If an exhaust brake is incorporated in the engine, the throttle valve shall be fixed fully open.
e
The fuel feed pressure may be adjusted, if necessary, to reproduce the inlet pump pressure conditions consist­
ent with the particular engine application (particularly where a "fuel return" system, e.g. to tank or filter, is used).
f
  The air inlet valve is the control valve for the pneumatic governor of the injection pump. The governor of the
fuel injection equipment may contain other devices which may affect the amount of fuel injected.
g
  The radiator, fan, fan cowl, water pump and thermostat shall be located on the test bed in the same relative
positions that they will occupy on the vehicle. The cooling liquid circulation shall be operated by the engine
water pump only.
Cooling of the liquid may be produced 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 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 6.2 shall be deducted from the corrected power.
h
  Where a separate disconnectable or progressive fan or blower is incorporated, the test shall be made with
the disconnectable fan or blower disconnected or with the progressive fan running at the maximum slip.
i
  The thermostat may be fixed in the fully open position. For the case of an active thermal management sys­
tem, control settings shall be representative of full load operation.
j
  Minimum power of the generator/alternator: the power of the generator/alternator shall be limited to that
necessary for the operation of accessories which are indispensable for engine operation. If the connection of a
battery is necessary, a fully charged battery in good order shall be used.
k
  Charge-air-cooled engines shall be tested complete with charge-air-cooling whether liquid or air-cooled
but if the engine manufacturer prefers, a test bed system may replace the air-cooled cooler. In either case, the
measurement of power at each speed shall be made with the pressure drop and temper
...