ISO/TR 14396:1996
(Main)Reciprocating internal combustion engines — Determination and method for the measurement of engine power
Reciprocating internal combustion engines — Determination and method for the measurement of engine power
Method of determining power of RIC engines as equipped when used for an exhaust emission test according to ISO 8178. Applicable to engines used to propel road construction and earth moving machines and industrial trucks.
Moteurs à combustion interne — Détermination et méthode de mesure de la puissance
General Information
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Standards Content (Sample)
ISO/TR 14396: 1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
The main task of technical committees is to prepare International
Standards, but in exceptional circumstances a technical committee may
propose the publication of a Technical Report of one of the following
types:
- type 1, when the required support cannot be obtained for the
publication of an International Standard, despite repeated efforts;
- type 2, when the subject is still under technical development or
where for any other reason there is the future but not immediate
possibility of an agreement on an International Standard;
- type 3, when a technical committee has collected data of a different
kind from that which is normally published as an International
Standard (“state of the art”, for example).
Technical Reports of types 1 and 2 are subject to review within three
years of publication, to decide whether they can be transformed into
International Standards. Technical Reports of type 3 do not necessarily
have to be reviewed until the data they provide are considered to be no
longer valid or useful.
lSO/rR 14396, which is a Technical Report of type 2, was prepared
by Technical Committee ISO/TC 70, internal combustion engines,
Subcommittee SC 2, Performance and tests.
0 IS0 1996
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 the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
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llSO/TR 14396:1996(E)
INTRODUCTION
In comparison with engines for on-road applications engines for off-road use are made
figuration and are used in a great
in a much wider range of power output and con
number of different applications.
The objective of IS0 8178 is to rationalise the gaseous and particulate emissions test
procedures for off-road engines in order to simplify and make more cost effective the
drafting of legislation, the development of engine specifications and the certification of
engines.
One of the concepts that has been adopted to achieve these objectives is to calculate
the specific emissions, g/kWh, on the basis of the engine power when only the essential
dependent auxiliaries are fitted.
IS0 8178 has been used for legislation and the authorities have set limit values that
vary according to the power of the engine. This Technical Report defines the procedure
to be used to determine the power of the engine for IS0 8178 testing.
The calculation of specific emissions according to IS0 8178 is based upon uncorrected
power measurement values since the emissions also vary with ambient conditions but
cannot be corrected. The allowable range of variation of ambient conditions in this
Technical Report is therefore very small in order to minimize ambient effects.
In comparison to IS0 3046-l which also defines the power measurement including the
power correction procedures this Technical Report defines the specific auxiliaries and
equipment to meet the needs of supporting the emissions legislation. Due to the fact
that IS0 3046 is intended to suit the needs of all engines for all kinds of applications
there are 15 definitions of power contained in IS0 3046, so that it is not sufficiently
specific to meet the needs of supporting the emissions legislation.
This Technical Report, which is to be used to determine the engine power prior to an
emissions test so that the correct limit values can be applied, employs power correction
procedures so that a wider range of ambient conditions can be used.
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TECHNICAL REPORT @ IS0
ISO/TR 14396: 1996(E)
Reciprocating internal combustion engines -
Determination and method for the measurement of engine
power
1 SCOPE
This Technical Report specifies the method of determining the power of RIC
engines as equipped when presented for an exhaust emssions test according
to IS0 8178.
It also specifies the power correction method for the confirmation of engine
power for preset engines under variable atmospheric conditions. These
corrections do not apply to the definition of the exhaust emission values which
are in all cases related to the uncorrected engine power only.
This Technical Report is applicable to RIC engines for land, rail traction and
marine use excluding engines for motor vehicles primarily designed for road
use. It may be applied to engines used to propel e.g. road construction and
earth-moving machines, industrial trucks and for other applications.
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@ IS0
ISO/TR 14396: 1996(E)
REFERENCES
Reciprocating internal combustion engines - Vocabulary
IS0 271 O-l :-I)
Part 1: Terms for engine design and operation
Reciprocating internal combustion engines- Performance
IS0 3046-I: 1995
Part 1: Standard reference conditions, declarations of
power, fuel and lubricating oil consumptions, and test
methods
Petroleum products - Transparent and opaque liquids -
IS0 3104:1994
Determination of kinematic viscosity and calculation of
dynamic viscosity.
Crude petroleum and liquid petroleum products -
IS0 3675: 1993
Laboratory determination of density or relative density -
Hydrometer method.
IS0 5163: 1990 Motor and aviation type fuels - Determination of knock
characteristics - Motor method.
Motor fuels - Determination of knock characteristics -
IS0 5164: 1990
Research method.
Diesel fuels - Determination of ignition quality - Cetane
IS0 5165:-*)
engine method.
Fuel injection equipment - Vocabulary - Part 1: Fuel
IS0 7876-l : 1990
injection pumps.
Reciprocating internal combustion engines - Vocabulary
SO 7967-l: 1987
of components and systems - Part 1: Structure and
external covers.
Reciprocating internal combustion engines - Vocabulary
SO 7967-2: 1987
of components and systems - Part 2: Main running gear.
Reciprocating internal combustion engines -
IS0 7967-3: 1987
Vocabulary of components and systems - Part 3:
Valves, camshaft drive and actuating mechanisms.
Reciprocating internal combustion engines -
IS0 7967-4: 1988
Vocabulary of components and systems - Part 4:
Pressure charging and air/exhaust gas ducting
systems.
1)
To be published. (Revision of IS0 271 O-1 :1978 and of its addendum 1 :1982)
2)
To be published. (Revision of IS0 5165:1992)
2
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ISO/TR 14396: 1996(E)
IS0 7967-5: 1982 Reciprocating internal combustion engines -
Vocabulary of components and systems - Part 5:
Cooling systems.
IS0 7967-8: 1994 Reciprocating internal combustion engines -
Vocabulary of components and systems - Part 8 :
Starting systems.
IS0 8178-l :1996 Reciprocating internal combustion engines - Exhaust
emission measurement - Part 1: Test bed
measurement of gaseous and particulate emissions.
IS0 817802:1996 Reciprocating internal combustion engines - Exhaust
emission measurement - Part 2: Measurement of
gaseous and particulate exhaust emissions at site.
Reciprocating internal combustion engines - Exhaust
IS0 8178-4: 1996
emission measurement - Part 4: Test cycles for
different engine applications.
IS0 81 78-5:-3) Reciprocating internal combustion engines - Exhaust
emission measurement - Part 5: Specification of test
fuels.
IS0 81 78-6:-3)
Reciprocating internal combustion engines - Exhaust
emissions measurement - Part 6: Test report.
Reciprocating internal combustion engines - Exhaust
IS0 8178-7: 1996
emission measurement - Part 7: Engine Family
determination.
Reciprocating internal combustion engines - Exhaust
IS0 8178-8:1996
emission measurement - Part 9: Engine Group
determination.
ASTM D 240-87 Standard test method for heat of combustion of liquid
hydrocarbon fuels by bomb calorimeter.
ASTM 3338-88
Standard test method for estimation of heat of
combustion of aviation fuels.
3) To be published.
3
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ISO/TR 14396: 1996(E)
DEFINITIONS
For the purposes of this Technical Report, the definitions given in IS0
2710-1, IS0 7876-1, IS0 7967-1, IS0 7967-2, IS0 7967-3, IS0 7967-4, IS0
7967-5 and IS0 7967-8, and the following definitions apply.
Engine Power for IS0 8178: Power obtained on a test-bed at the end of the
31 .
crankshaft or its equivalent, at the declared engine speed specified by the
manufacturer at the declared power with the engine being fitted only with
equipment and auxiliaries as listed in Table 1.
All equipment and auxiliaries not required by Table 1 should be removed.
Where accessories cannot be removed, the power absorbed by them in the
unloaded condition shall be determined and added to the measured engine
power. If this value is greater than 3% of the maximum power at the test
speed it may be verified by the test authority.
Where equipment and auxiliaries required by Table 1 are not fitted for the
test, the power absorbed by them in the loaded condition shall be determined
and subtracted from the measured power If this value is less than 3% of the
maximum power at the test speed it may be verified by the test authority.
32 . Standard Production Equipment: Equipment specified by the manufacturer
for a particular engine application and that is fitted as standard to the engine.
33 . Declared Engine Speed: The engine speed declared by the engine
manufacturer corresponding to the declared power.
34 . Intermediate Engine Speed
The intermediate engine speed shall be declared by the manufacturer taking
into account the following requirements.
For engines which are designed to operate over a speed range on a
a>
full load torque curve, the intermediate speed shall be the declared
maximum torque speed if it occurs between 60% and 75% of declared
speed.
If the declared maximum torque speed is less than 60% of declared
speed, then the intermediate speed shall be 60% of the declared
speed.
If the declared maximum torque speed is greater than 75% of the
declared speed, then the intermediate speed shall be 75% of the
declared speed.
For engines which are not designed to operate over a speed range on
W
the full load torque curve at steady state conditions, the intermediate
speed will typically be between 60% and 70% of the maximum
declared speed.
4
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ISO/TR 14396: 1996(E)
0 IS0
ACCURACY OF THE MEASURING EQUIPMENT AND INSTRUMENTS
4
41 . Torque: The dynamometer torque measuring system shall have an accuracy
within & 1 % in the range of scale values required for the test’)
Engine speed
42 .
The engine speed measuring system shall have an accuracy of f 0,5%
Fuel flow: The fuel flow measuring system shal have an accuracy of k 1%.
43 .
44 . Fuel temperature: The fuel temperature measuring system shall have an
accuracy of & 2 K.
Engine inlet air temperature: The air temperature measuring system shall
45 .
have an accuracy of f 2 K.
Barometric pressure: The barometric pressure measuring system shall
46 .
have an accuracy of * 100 Pa
47 . Back pressure in exhaust system: The system used to measure the back
pressure in the exhaust system shall have an accuracy of k 200 Pa.
Depression in inlet system: Subject to footnote 1 a) in table 1, this pressure
48 .
shall be measured to & 50 Pa.
1
The torque measuring system shall be calibrated to take friction losses into account.
>
The accuracy in the lower half of the measuring range of the dynamometer bench
may be it 2 % of measured torque.
5
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lSO/TR 14396: 1996(E)
5 TEST FOR MEASURING ENGINE POWER FOR IS0 8178
51 . Equipment and auxiliaries
51.1 Equipment and auxiliaries to be fitted
During the test, the equipment and auxiliaries as listed in Table 1 shall be
installed on the test bed.
5.1.2 Equipment and auxiliaries to be removed
Certain machine accessories necessary only for the operation of the machine
and which may be mounted on the engine should be removed for the test.
The following non-exhaustive list is given as a sample:
air compressor for brakes,
power-steering pump
suspension compressor,
air-conditioning system compressor.
mounted gearbox.
6
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ISO/TR 14396: 1996(E)
62 IS0
TABLE 1
Equipment and auxiliaries to be installed for the test to determine engine power for IS0 8178
Equipment and Auxiliaries Fitted for Engine Power Test
No .
1 Inlet system
Inlet manifold
Yes, standard production equipment.
Crankcase emission control system
Yes, standard production equipment
Control devices for dual induction Yes, standard production equipment
inlet manifold system
Air flow meter Yes, standard production equipment
Air inlet duct work Yes ‘)
Air filter Yes ‘)
Inlet silencer Yes ‘)
Speed-limiting device Yes ‘)
Induction-heating device of Yes, standard production equipment.
2
inlet manifold If possible to be set in the most
favourable condition.
3 Exhaust system
Exhaust purifier Yes, standard production equipment
Exhaust manifold Yes, standard production equipment
Pressure charging device Yes, standard production equipment
Connection pipes
Exhaust brake
Carburation Equipment
Yes, standard production equipment
Yes, standard production equipment
Electronic control system, air flow
meter, etc.
Equipment for gas engines
Yes, standard production equipment
Pressure reducer
Evaporator Yes, standard production equipment
Mixer Yes, standard production equipment
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lSO/TR 14396: 1996(E)
TABLE 1 - CONTlD
Equipment and Auxiliaries Fitted for engine power test
No .
Fuel injection equipment
6
(petrol and diesel)
Yes, standard production or test bed
Prefilter
equipment
Yes, standard production or test bed
Filter
equipment
Yes, standard production equipment
Pump
Yes, standard production equipment
High pressure pipe
Yes, standard production equipment
Injector
Yes, standard production equipment 5,
Air inlet valve
Electronic control system, air flow Yes, standard production equipment
meter, etc.
Governor/control system Yes, standard production equipment
Automatic full-load stop for the control Yes, standard production equipment
rack depending on atmospheric
conditions
Liquid-cooling equipment
Radiator No
No
Fan
Fan cowl No
Water pump Yes, standard production equipment 6,
Thermostat Yes, standard production equipment 7,
Air cooling
Cowl No
Fan or Blower No 8,
Temperature-regulating device No
8
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ISOBTR 14396:1996(E]
TABLE 1 -CONT/D
Equipment and Auxiliaries Fitted For Engine Power Test
No .
Electrical Equipment
9
Generator Yes, standard production equipment ‘)
Spark distribution system Yes, standard production equipment
Coil or coils
Yes, standard production equipment
Wiring Yes, standard production equipment
Spark plugs Yes, standard production equipment
Electronic control system including Yes, standard production equipment ‘*I
knock sensor/spark retard system
Pressure charging equipment
10
Compressor driven either directly
by the engine and/or by the exhaust
Yes, standard production equipment
gases
Boost control Yes, standard production equipment 13)
Charge air cooler Yes, standard production or test bed
equipment 8t lo)
Coolant pump or fan (engine-driven) No 8,
Coolant flow control device Yes, standard production equipment
Auxiliary test-bed fan Yes, if necessary
Anti-pollution device
Yes, standard production equipment “)
Lubricating Oil Pump
Yes, standard production equipment
1)
The complete inlet system shall for the intended application be fitted :
a
where there is a risk of an appreciable effect on the engine power;
a
in the case of naturally aspirated spark ignition engines;
l
when the manufacturer requests that this.should be done.
In other cases, an equivalent system may be used and a check should be made to
ascertain that the inlet pressure does not differ by more than 100 Pa from the upper
limit specified by the manufacturer for a clean air filter.
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ISO/TR 14396: 1996(E)
0 IS0
2)
The complete exhaust system for the intended application shall be fitted:
l
where there is a risk of an appreciable effect on the engine power;
0
in the case of naturally aspirated spark ignition engines;
a when the manufacturer requests that this should be done.
In other cases an equivalent system may be installed provided that the pressure
measured does not differ by more than 1000 Pa from the upper limit specified by the
manufacturer.
3)
If an exhaust brake is incorporated in the engine, the throttle valve shall be fixed in
the fully open position.
4)
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
e.g. to tank or filter, is used).
5)
The air inlet valve is the control valve for the pneumatic governor of the injection
pump. The governor or the fuel injection equipment may contain other devices which
may affect the amount of injected fuel.
6)
The cooling-liquid circulation shall be operated by the engine water pump only.
Cooling of the liquid may be produced by an external circuit, such 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.
7)
The thermostat may be fixed in the fully open position.
8)
When the cooling fan or blower is fitted for the test, the power absorbed shall be
added to the test results. The fan or blower power shall be determined at the speeds
used for the test either by calculation from standard characteristics or by practical
tests.
9)
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.
10)
Charge air-cooled engines shall be tested with the charge air cooling system
operating, whether this system is liquid or air cooled. If the 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 maximum pressure drop and the
minimum temperature drop of the engine air across the charge air-cooler on the test
bed system the same as those specified by the manufacturer.
11)
These may include, for example, exhaust-gas recirculation (EGR), catalytic
converter, thermal reactor, secondary air-supply system and fuel evaporation
protecting system.
12)
The spark advance shall be representative of in-use conditions established with the
minimum octane fuel recommended by the manufacturer.
13)
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 or in-machine conditions established with the minimum
octane fuel as recommended bv the manufacturer.
10
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@ IS0 ISO/TR 14396: 1996(E)
52 . Setting conditions
The setting conditions for the test to determine the engine power for IS0
8178 are indicated in Table 2.
TABLE 2
Setting conditions
1 Setting of carburettor(s)
,
1
2 Setting of injection-pump
Set in accordance with the
delivery system
manufacturer’s
3 Ignition or injection timing
(timing curve)
specifications and used
Governor setting
II4 I I
without further alteration for
5 Anti-pollution devices
I
lr I
the particular engine application
6 Boost control
I
lr I
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ISO/TR 14396: 1996(E)
53 .
Test conditions
The settings for the engine power test depend upon whether the engine is ‘pre-
53.1
set’ and will run at full fuel delivery under all conditions, or if the engine is
‘adjustable’ and will be adjusted to produce a specified power output.
For spark ignition engines the engine power test shall consist of a run at full
throttle, the engine being equipped as specified in Table 1.
For pre-set compression ignition engines the engine power test shall consist of
a run at the fixed full load fuel injection pump setting, the engine being equipped
as specified in Table 1.
For adjustable compression ignition engines the engine power test shall consist
of a run at the required fuel system settings for the manufacturer’s specified
power, the engine being equipped as specified in Table 1.
Performance data shall be obtained under stabilized operating conditions, with
5.3.2
an adequate fresh-air supply to the engine. The engine shall have been run-in
in accordance with the manufacturer’s recommendations. Combustion
chambers may contain deposits, but in limited quantity.
Test conditions such as inlet air temperature shall be selected as near to
reference conditions (see 6.2) as possible in order to minimize the magnitude
of the correction factor.
The temperature of the inlet air to the engine shall be measured within the inlet
5.3.3
ductwork. The inlet depression measurement shall be made at the same point.
The thermometer or thermocouple shall be shielded from radiant heat and
placed directly in the air stream. It shall also be shielded from fuel spray-back.
A sufficient number of locations shall be used to give a representative average
inlet temperature.
5.3.4 The inlet depression shall be measured downstream of the entry ducts, air filter,
inlet silencer, speed limiting device (if they are fitted) or their equivalents.
5.3.5 The absolute pressure at the entry to the engine, downstream of the
compressor and heat exchanger if they are fitted, shall be determined in the
inlet manifold and at any other point where pressure has to be measured to
calculate correction factors.
5.3.6 The exhaust back pressure shall be measured at a point at least three pipe
diameters downstream from the outlet flange(s) of the exhaust manifold(s) and
downstream at the turbocharger(s), if fitted. The location shall be specified.
5.3.7 No data shall be taken until torque, engine speed and temperatures have been
maintained substantially constant as specified by the manufacturer.
12
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ISO/TR 14396:1996(E)
@ IS0
The engine speed during a run or reading shall not deviate from the selected
5.3.8
speed by more than * I % or f 10 min-I, whichever is greater.
5.3.9 Observed torque, fuel flow and inlet air temperature data shall be taken
simultaneously and shall, in each case, be the average of at least two stabilized
consecutive readings. No adjustment shall be made to the engine between
these readings.
The temperature of the coolant at the outlet from the engine shall be kept within
5.3.10
& 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 +O/-20 K of the maximum value specified by the
manufacturer for the reference conditions.
Fuel temperatures shall be as follows:
5.3.11
For spark-ignition engines, the fuel temperature shall be measured as
a)
near as possible to the inlet of the carburettor or assembly of fuel
injectors. Fuel temperature shall be maintained within * 5K 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
298K * 5K.
For compressions-ignition engines, the fuel temperature shall be
W
measured at the inlet to the fuel-injection pump. At the manufacturer’s
request the fuel temperature measurement can be made at another
point in the pump representative of the engine operating condition or in
the fuel supply pipe between the filter and the injection pump, upstream
of the entry point for any backflow fuel. Fuel temperature shall be
maintained within & 3K of the temperature specified by the
manufacturer. In all cases, the minimum allowable fuel temperature at
the pump entrance is 306 K. If the test fuel temperature is not specified
by the manufacturer, it shall be 313 K f 3K for distillate fuels.
The temperature of the lubricating oil shall be measured at either the gallery
5.3.12
inlet, the outlet from the oil cooler, if fitted, or as specified by the manufacturer.
The temperature shall be maintained within the limits specified by the
manufacturer.
An auxiliary regulation system may be used if necessary to maintain the
5.3.13
temperatures within the limits specified in 5.3.10, 5.3.11 and 5.3.12.
13
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lSO/TR 14396: 1996(E)
5.3.14 Fuel
The selection of the fuel for the IS0 8178 power test shall be the same as that
used for the IS0 8178 emissions test. Unless otherwise agreed by the parties
involved the fuel shall be selected in accordance with the following table.
TABLE 3
Test Fuels
Interested parties Fuel selection
Test Purpose
1. Certification body - Reference fuel, if one
Type approval
2. Manufacturer or supplier
(Certification) is defined
- Commercial fuel if no
reference fuel is
defined
1. Manufacturer or supplier
Acceptance test - Commercial fuel as
2. Customer or inspector specified by the
manufacturer
54 . Test procedure
For variable speed engines measurements shall be taken at a sufficient number
of engine speeds to define the power curve completely between the lowest and
the highest engine speeds recommended by the manufacturer, For each speed,
the average of at least two stabilized measurements shall be determined.
For constant speed engines and those driving equipment which determines the
speed dependent torque characteristics, e.g., a propeller, measurements shall
be made at the declared speed and declared power.
55 . Data to be recorded
Data to be recorded are those indicated in Clause 8.
14
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0 IS0
ISO/TR 14396: 1996(E)
6 . POWER CORRECTION FACTORS
61 ‘ Definition of factor a for power correction
The power correction factor is the coefficient by which the observed power shall
be multiplied to determine the engine power under the reference atmospheric
The corrected power (i.e. power at reference
conditions specified in 6.2.
conditions), Pref, is given by
where
a is the correction factor (a, for spark-ignition engines or a, for compression
ignition engines);
P, is the measured power (observed power)
62 . Atmospheric conditions
6.2.1 Reference atmospheric conditions
For the purpose of determining the power of an engine, the standard
reference conditions according to 6.2.1 .l and 6.2.1.2 shall be used.
6.2.1 .l Reference temperature, Trer : 298 K (25°C)
6.2.1.2 Reference dry barometric pressure, pdref : 99 kPa
.
Note: The dry pressure is based on a total barometric pressure of 100 kPa
and a water vapour pressure of 1 kPa.
Test atmospheric conditions
6.2.2
The atmospheric conditions during the test shall be within the ranges
according to 6.2.2.1 and 6.2.2.2
Temperature, T
6.2.2.1
For spark-ignition engines
288K1 T~308K
For compression-ignition engines
283Ki T<313K
6.2.2.2 Dry Pressure, pd
For all engines
90kParp&lOkPa
15
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lSO/TR 14396: 1996(E)
a,
63 . Determination of power correction factors a, and
The test may be carried out in air-conditioned test rooms where the amospheric
conditions are controlled to equal the reference conditions. In the case of
engines fitted with automatic air temperature control, if the device is such that
at full load at 25OC no heated air is added, the test shall be carried out with the
device operating normally and the exponent of the temperature term in the
correction factor clause 6.3.1 shall be taken as zero (no temperature
correction).
Naturally aspirated or pressure-charged spark-ignition engines - Factor
6.3.1
a,:
99 T
L2 Or6
a=
( > ( >
a
298
pd
where
T is the absolute temperature in Kelvins (K) of the air drawn in by the engine;
pd is the dry atmospheric pressure in kilopascals (kPa), that is, the total
barometric pressure minus the water vapour pressure.
For a test to be valid, the correction factor a, must be such that:
0,96 s a, I I,06
If these limits are exceeded, the corrected value obtained shall be given and the
test conditions (temperature and pressure) precisely stated in the test report.
Compression-ignition engines - Factor a,
6.3.2
The power correction factor (a,) for compression-ignition engines at constant
fuel del
...
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