1. C O N S E I L I N T E R N A T I O N A L I N T E R N A T I O N A L C O U N C I L
DES MACHINES A COMBUSTION O N C O M B U S T I O N E N G I N E S
PAPER NO.: 23
Stroke by stroke measurement of diesel engine
performance on board
M.Sc. Lars Karlsson, ABB Automation Technology Products AB, Sweden
lars.o.karlsson@se.abb.com
Ph.D. Jarl Sobel, ABB Automation Technology Products AB, Sweden
Abstract: The objective of this paper is to
present long time continuously measured diesel
engine performance data for large 2-stroke diesel
engines in propulsion applications. The unique
feature is that every single stroke is measured and
used in the data evaluation. We will show how this
feature makes it possible to identify errors in the
engine at a very early stage, and to follow up the
running conditions of the engine.
The measurement system used is the
Cylmate® Diesel Engine Performance Monitoring
System. The system measures the combustion
pressure continuously in real time and in all
cylinders in parallel. Further, the crank angles for
each cylinder are calculated with high precision
using accurate flywheel angle measurement and a
calculation model for the twist of the crankshaft.
We present data obtained from five different
vessels. An application case from the vessel M/V
Malmoe Link is outlined. Due to continuous
measurement and supervision of the combustion
process, the crew detected a fault in the cooling of
a fuel valve.
The vessel M/V Hanjin Ottawa is equipped with
a power meter which makes it possible to compare
indicated power and brake power. We have also
computed the mechanical efficiency and the loss
power stroke by stroke. An application case, where
a beginning fault of an exhaust gas valve was
detected in an early stage with help of Cylmate, is
presented.
Data from the two sister vessels M/V Anna
Maersk and M/V Axel Maersk are compared
showing a very close agreement in the measured
parameters. When analyzing data from M/V Axel
Maersk a change in the combustion process
around June 20, 2003 was identified. It was later
confirmed by the crew that a change of fuel with a
following adjustment of the engine had taken place
at that time.
The longest period of time with continuously
measured data presented in this paper is from M/V
Anna Maersk. These data covers 81 days of
operation where approximately 7.3 million strokes
per cylinder were measured and used in the
analysis.
Three of the pressure transducers on M/V
Maersk Arun are early prototypes and have been in
continuous operation since the installation in year
2001. We show data with more than two years
interval showing close agreement.
© CIMAC Congress 2004, Kyoto

2. INTRODUCTION
The objective of this paper is to present long time
continuously measured diesel engine performance
data for large 2-stroke diesel engines in propulsion
applications. The unique feature is that every single
stroke is measured and used in the data evaluation
and we will show how this feature makes it possible
to identify errors in the engine at a very early stage,
and to follow up the running conditions of the
engine.
The measurement system used is the newly
developed Cylmate® Diesel Engine Performance
Monitoring System. The system measures the
combustion pressure continuously in real time and
on all cylinders in parallel. Further, the crank angles
for each cylinder are calculated with high precision
using accurate flywheel angle measurements and a
calculation model for the twist of the crankshaft.
The system is outlined in the paper.
The system gives the possibility to minimize fuel
consumption and to carry through condition-based
maintenance. The combination of continuous
measurement and high accuracy makes online
overload protection possible. The engine can easily
be power-balanced and tuned in order to improve
the running performance.
The present paper shows engine performance data
from several 2-stroke diesel engines. Further, the
advantage of continuously measuring and
monitoring the combustion process is shown with
some case studies.
MEASUREMENT SUMMARY
The unique feature is that every single stroke is
measured and used in the data evaluation. This
feature makes it possibly to identify errors in the
engine at a very early stage, and to follow up the
running conditions of the engine.
In the present paper we show results from
measurements where each single stroke has been
stored in the trend files. We also show long term
data where the data has been averaged over 100
strokes before storage. The reason for that is to
make it feasible to collect and analyze data over
long periods of time.
We present data obtained on five different vessels.
First, we show data from the vessel M/V Malmö
Link, where data from two different weeks is
compared. The first Cylmate system was installed
in M/V Malmö Link in 2001. An application case
from M/V Malmö Link is then outlined. Due to
continuous measurement and supervision of the
combustion process, the crew detected a fault in
the cooling of a fuel valve.
Further, we show data from the vessel M/V Hanjin
Ottawa where each single stroke for a 2 hours
voyage was stored in the trend files. The section
with M/V Hanjin Ottawa data is finished with an
application case where a faulty exhaust valve was
detected with help of Cylmate.
Data from the two sister vessels M/V Anna Maersk
and M/V Axel Maersk is then compared showing a
very close agreement in the measured parameters.
For M/V Axel Maersk data from 20 days of
operation, which corresponds to about 2 million
strokes, is shown. When analyzing these data a
change in the combustion process around June 20,
2003 was identified. It was later confirmed by the
crew that a change of fuel with a following
adjustment of the engine had taken place at that
time.
The longest period of time with continuously
measured data presented in this paper is from M/V
Anna Maersk. These data covers 81 days of
operation where approximately 7.3 million strokes
per cylinder were measured and used in the
analysis.
Three of the pressure transducers on Maersk Arun
are early prototypes and have been in operation all
the time since the installation in year 2001. We
show measurements with more then two years
interval showing close agreement.
M/V MALMÖ LINK
M/V Malmö Link is a ro-pax ferry with two Sulzer
6RND68M engines. On the port main engine of this
vessel, the first Cylmate system was installed early
in year 2001. One year later, the starboard main
engine was also equipped with Cylmate.
M/V Malmö LinkFigure 1 —
© CIMAC Congress 2004, Kyoto Paper No. 23 2

3. M/V Malmö Link runs 13 times weekly between
Malmö in Sweden and Travemünde in Germany.
Information about the measurements presented in
this section can be found in the following table.
However, in this case the crew established the
cause to be a blocked water cooling tube, due to a
stretched screen cover, see figure 3. This made the
fuel valve needle stick.
Table 1 — M/V Malmö Link measurement overview
Vessel M/V Malmö Link
Date 2003 Week 19 and 40
No. of data points ≈8000/week
No. of strokes ≈800000/week
Average of for both engines and both weeks
are compared in two graphs in appendix 1. One
can see that the difference between the two
engines is smaller for the last measurement. In
appendix 1 there are also comparisons of MIP,
average angle of and indicated power
between the two engines, for the two weeks.
maxp
maxp
Blocked water cooling tubeFigure 3 —
M/V HANJIN OTTAWA
M/V Malmö Link – Cooling of fuel valve
M/V Hanjin Ottawa is a large container vessel with
a Wärtsilä NSD 10RTA96C engine.
The vessel M/V Malmö Link identified a problem
with cylinder 5 on starboard main engine. For all
loads, except full load, the pressure was
significantly lower than on the other cylinders.
Initially, the crew changed the fuel valve, but the
problem came back after 7-8 hours.
In figure 2 trend data for a 9 hour trip between
Travemünde and Malmö is shown using the
Cylmate Operator Station. The data displayed is
engine speed and for cylinders 4, 5 and 6.maxp
M/V Hanjin OttawaFigure 4 —
Stroke-by-stroke engine performance analysis
Information about the measurements presented in
this section can be found in the following table.
Table 2 — M/V Hanjin Ottawa measurement
overview
Vessel M/V Hanjin Ottawa
Date September 9, 2003
No. of strokes 12058Trend picture from M/V Malmö LinkFigure 2 —
With a non-continuous measuring system, you
perform measurements at nominal load, making it
impossible to see and analyze this problem, which
only appeared at low load.
In the figure below, the engine speed is shown for
the first part of the voyage between Yantian and
Kaohsiung. The first part of the plot shows the
© CIMAC Congress 2004, Kyoto Paper No. 23 3

4. vessel maneuvering out of Yantian, then speed was
increased gradually. After 40 minutes, the fuel was
switched off, the vessel went down in speed, and
then after some minutes the speed was increased
again.
Indicated power and brake powerFigure 7 —
The fuel index does not correlate perfectly with the
indicated power on a stroke-by-stroke basis. When
speeding up, the indicated power obtained is lower
than the value expected from the fuel index.
Similarly, when the engine slows down, the
indicated power obtained is larger than the value
expected from the fuel index. This must be due to
delays in the control system.
Engine speedFigure 5 —
The MIP values for each of the ten cylinders are
shown in appendix 2. The MIP values are strongly
influenced by any error in the TDC location. The
thermodynamic TDC, computed from the pressure
curve for each cylinder, is shown versus time in
appendix 2, and is in very good agreement with the
expected behavior. The conclusion is that the
crank-shaft deformation model of Cylmate predicts
the thermodynamic TDC of each cylinder in a very
proper way, and thus the accuracy in the calculated
MIP values are very high.
The mechanical efficiency is presented in the
following figure, and in appendix 2 the loss power is
shown as a function of engine speed.
Further, the indicated power and the brake power
are shown in the following two figures as a function
of time and fuel index, respectively.
Mechanical efficiencyFigure 8 —
M/V Hanjin Ottawa – Change of exhaust valve
The pressure at Top Dead Center (TDC) of cylinder
5 was lower than the other, especially noticeable at
low rpm and low scavenging air pressure, see
figure 9. The data displayed is engine speed and
for cylinders 1, 2 and 5.TDCpIndicated power and brake powerFigure 6 —
© CIMAC Congress 2004, Kyoto Paper No. 23 4

5. Large container vessel from
Maersk
Figure 11 —
Table 3 —
Information about the measurements can be found
in the following table.
M/V Anna Maersk and M/V Axel Maersk
comparison overviewFigure 9 — Trend picture from M/V Hanjin
Ottawa. Before change of exhaust valve.
Vessel M/V Anna Maersk
Date June 7-July 8, 2003
No. of data points 26511
No. of strokes 2651100
Vessel M/V Axel Maersk
Date June 10-30, 2003
No. of data points 19677
No. of strokes 1967700
After the change of exhaust valve on cylinder 5, the
pressure at TDC came back to normal, see figure
10.
On overview of the engine speed as a function of
time for M/V Axel Maersk is given in the following
figure, where also the ports are indicated. The
corresponding graph for M/V Anna Maersk can be
found in one of the coming subsections, where an
analysis covering a longer period of time is
presented.Figure 10 — Trend picture from M/V Hanjin
Ottawa. After change of exhaust valve.
The reason for the problem was that a leaking air
spring deteriorated the closing of the valve.
COMPARISON BETWEEN SISTER
VESSELS
In the present section a comparison between
combustion data obtained on two sister vessels is
performed. The vessels, M/V Anna Maersk and
M/V Axel Maersk, are large container vessel with
Wärtsilä NSD 12RTA96C engines. Engine speedFigure 12 —
When comparing average MIP as a function of
power for the two sister vessels, there is a very
close agreement, see figure 13.
© CIMAC Congress 2004, Kyoto Paper No. 23 5

6. In appendix 3 figures presenting average and
mechanical efficiency versus power can be found.
maxp
Average MIP vs. fuel indexFigure 15 —
Average MIP vs. powerFigure 13 — Long time data from M/V Anna Maersk
The longest period of time with continuously
measured data presented in the present paper is
from M/V Anna Maersk and covers 81 days of
operation. Information about the measurements
presented in this section can be found in the
following table.
Change of fuel on M/V Axel Maersk
When analyzing data from M/V Axel Maersk a
change in the combustion process around June 20,
2003 was identified. It was later confirmed by the
crew that a change of fuel with a following
adjustment of the engine had taken place at that
time. In figure 14, presenting the average angle of
maximum pressure versus fuel index, the influence
of the change in the combustion process is clearly
seen. The change of fuel did not influence average
MIP, as seen in figure 15.
Table 4 — M/V Anna Maersk measurement
overview
Vessel M/V Anna Maersk
Date June 7-August 26, 2003
No. of data points 73283
No. of strokes 7328300
In figure 16, the engine speed as a function of time
is shown, where also some of the ports are
indicated. The route is also indicated in figure 17.
Average angle of vs. FImaxpFigure 14 —
Engine speed vs. timeFigure 16 —
© CIMAC Congress 2004, Kyoto Paper No. 23 6

7. measured with these specific transducers are
approximately 70 millions per transducer.
Results from these three original pressure
transducers are shown in the following figure.
versus scavenging air pressure is plotted for two
different periods of time with 2 years interval. Note
that the values of for each of the three
pressure transducers are plotted in the same color
during a measurement period.
maxp
maxp
Route mapFigure 17 —
Maersk Arun
0
20
40
60
80
100
120
140
160
0 0,5 1 1,5 2 2
Pscav [bar]
Pmax[bar]
,5
Voyage 0374 2001-07-07
In figure 18 the average MIP is presented as a
function of fuel index for engine speed over 60 rpm.
maxp from 3 pressure transducers
with 2 years interval
Figure 20 —
One can conclude that there is a very close
agreement between the two measurement periods
with more then two years interval.
Average MIP vs. fuel indexFigure 18 —
Further, in appendix 3, average of as a
function of time is also given.
maxp
CYLMATE® SYSTEM
M/V MAERSK ARUN Cylmate System is a new powerful tool developed
by ABB for 2-stroke diesel engine performance
monitoring. The system, which fits both marine and
power plant applications, is designed to withstand
marine environmental conditions and fulfills the
requirements according to the main classification
societies. The Cylmate analysis and monitoring
functions mean that the risk of mechanical or
thermal overload of specific cylinders or the engine
itself can be avoided. Further, the cylinder
conditions can be optimized and the engine can
easily be balanced and tuned in order to improve
the running performance. The Cylmate System
gives the possibility to optimize fuel consumption
and to carry through condition-based maintenance.
M/V Maersk Arun is a container vessel with a MAN
B&W 7S50MC engine. Cylmate was installed in
spring 2001 on Maersk Arun and it was the second
Cylmate installation.
M/V Maersk ArunFigure 19 —
Comparison of measurements with 2 years interval Cylmate® System consists of a Pressure
Transducer mounted on each cylinder and an
Angle Transducer at the engine flywheel. The
controller collects all measured data within each
engine working cycle via the Transducer Bus. A
built-in mathematical engine model computes, in
real-time, the crankshaft twist in order to get the
Three of the pressure transducers on Maersk Arun
are early prototypes and have been in continuous
operation since the installation in year 2001. One
can estimate that the total number of strokes
© CIMAC Congress 2004, Kyoto Paper No. 23 7

8. correct Top Dead Center (TDC) angle and piston
position. All combustion parameters, e.g. ,
, and
maxp
α−maxp TDCp MIP, are logged and
monitored for each stroke and can be shown in
trend diagrams.
The main goals in the development of this
continuously measuring system have been to
measure the combustion pressure with an accuracy
better than 0,5% and to calculate the indicated
power with an accuracy better than 2%.
A schematic picture of a Cylmate System is
shown in following figure.
Figure 21 — Cylmate System
The different system components are further
described in the following subsections.
Pressure transducers
The Pressure Transducers, which include a
number of ABB patents, are based on the well-
proven Pressductor® Technology with a blow-
through design that simplifies the cleaning and
maintenance of the pressure transducers from
combustion residues.
The measuring accuracy is 0.5% over the full range
and the accuracy is not influenced by any clogging
or heat flash from the combustion gases, which is a
common problem of membrane-based pressure
transducers.
The transducer is factory-calibrated and designed
for continuous combustion pressure measurement
24h per day, 365 days per year, without any need
of recalibration.
On each cylinder, close to the indicator bore, the
Cylmate Pressure Transducers are permanently
mounted. On the top of the transducers standard
indicator valves are mounted, see figure 22.
Cylmate Pressure TransducerFigure 22 —
Angle transducer
The Cylmate® Angle Transducer is mounted close
to the flywheel and is calibrated during system
commissioning. The Angle Transducer is using the
Pulsed Eddy Current Technology, patented by
ABB, which will find the magnetic middle of each
tooth with an accuracy of 0.05°. Since the number
of flywheel teeth may not be that big and the fact
that the flywheel rotates with an irregular velocity,
the system interpolates the angle values between
two teeth using the speed information from the four
closest tooth passage according to a 2nd order
polynomial. The total angle measuring concept
gives an outstanding accuracy and repeatability of
angle measurement independent of temperature,
distance, rotating speed and speed variations.
Cylmate Angle TransducerFigure 23 —
Engine Model
The Cylmate system has algorithms to determine
the static differences between the crank angles of
different cylinders, due to manufacturing tolerances
in the crankshaft. It also incorporates a dynamical
motor model, which computes the local twist of the
crankshaft at each cylinder and at each crank
angle. This guarantees an accuracy of the crank-
© CIMAC Congress 2004, Kyoto Paper No. 23 8

9. CONCLUSIONSweb angle of 0.1°CA. This computation is based on
the force from the gas pressure in the cylinders,
and the inertial forces acting on the cylinders. The main conclusion of this paper is that it is now
possible to measure, during a long period of time,
the combustion pressure continuously on large 2-
stroke diesel engines. When measuring
continuously it is possibly to identify errors in the
engine at a very early stage, and to follow up the
running conditions of the engine. Cylmate pressure
transducers, which have been in continuous
operation since the installation in year 2001, are
still measuring accurately.
It is known that the MIP value is strongly related to
the accuracy of the crank angle measurement. An
error in the crank angle of 1°CA gives about 8%
error in the MIP value. An example of the
crankshaft twist versus crank angle for a 8-cylinder
engine at 89 rpm is shown in figure 24.
NOMENCLATURE
maxp maximum combustion pressure
α−maxp angle of maximum pressure
TDCp pressure at Top Dead Center
Crankshaft DeformationFigure 24 —
MIP Mean Indicated Pressure
Operator Station IPOW Indicated power
The Cylmate® Operator Station has a software,
which is executed on an industrial version of a
standard PC. The Operator Station has
comprehensive on-screen presentation of all
collected data, both current and historical. Alarm,
event and trend pages as well as graphic and
tabular forms of the engine parameters are
available.
scavp Scavenging air pressure
ACKNOWLEDGEMENTS
We would like to give our acknowledgements to the
ship owners NSB, AP Möller and Nordö Link that
allowed us to use data from their vessels.
Example of Operator Station graphFigure 25 —
© CIMAC Congress 2004, Kyoto Paper No. 23 9

10. APPENDIX 1 For the most recent of the measurement weeks the
average angle of and the indicated power,
both versus engine speed, are shown in the
following two figures.
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M/V Malmö Link comparison of two weeks of
operation
Malmö Link Week340
8
9
10
11
12
13
14
90 95 100 105 110 115 120 125 130 135 140
Engine Speed [rpm]
AverageangleofPmax[deg]
Port Starboard
Data from two weeks of operation on M/V Malmö
Link with 21 weeks interval is shown. First, the
engine speed versus time for week 340 is shown.
Malmö Link Week340
70
80
90
100
110
120
130
140
2003-09-29 2003-10-01 2003-10-03 2003-10-05 2003-10-07
EngineSpeed[rpm]
Port Starboard
Average angle of week 340maxpFigure 29 —
Malmö Link Week340
0
1
2
3
4
5
6
7
8
40 50 60 70 80 90 100 110 120 130 140
Engine Speed [rpm]
IPOW[MW]
Port Starboard
Engine speed week 340Figure 26 —
In the following two figures average versus
engine speed is shown for the two weeks. One can
see that there is a smaller difference between the
engines for the last measurements.
maxp
Malmö Link Week319
70
72
74
76
78
80
82
84
86
88
90
125 126 127 128 129 130 131 132 133 134 135
Engine Speed [rpm]
Pmaxaverage[bar]
Port Starboard
Indicated power week 340Figure 30 —
In the following figure the average MIP on
starboard main engine is compared for the two
weeks.
Malmö Link Starboard Main Engine
5
6
7
8
9
10
11
12
13
90 95 100 105 110 115 120 125 130 135 140
Engine Speed [rpm]
MIPaverage[bar]
W319 W340
Average week 319maxpFigure 27 —
Malmö Link Week340
70
72
74
76
78
80
82
84
86
88
90
125 126 127 128 129 130 131 132 133 134 135
Engine Speed [rpm]
Pmaxaverage[bar]
Port Starboard
Average MIP Starboard engineFigure 31 —
Average week 340maxpFigure 28 —
© CIMAC Congress 2004, Kyoto Paper No. 23 10

11. APPENDIX 2
M/V Hanjin Ottawa stroke-by-stroke analysis
September 9, 2003
The engine speed for the measurement period is
shown in the figure below.
Thermodynamic TDCFigure 34 —
In the following figure, the loss power is shown as a
function of engine speed.
Engine speedFigure 32 —
The MIP values for each of the ten cylinders are
shown in the following figure.
Loss powerFigure 35 —
MIP for all cylindersFigure 33 —
The MIP values are strongly influenced by any error
in the TDC location. The thermodynamic TDC is
shown below, and is in very good agreement with
the expected behavior.
© CIMAC Congress 2004, Kyoto Paper No. 23 11

12. © CIMAC Congress 2004, Kyoto Paper No. 23 12
APPENDIX 3 In figure 38 and 39 average versus time and
fuel index, respectively, for 81 days of operation are
shown.
maxp
Comparison between M/V Anna Maersk and M/V
Axel Maersk
Average and mechanical efficiency, both
versus power, are compared for the sister vessels
in the following two figures.
maxp
Average vs. fuel indexmaxpFigure 39 —
Average vs. powermaxpFigure 36 —
Mechanical efficiency vs. powerFigure 37 —
81 days of operation onboard M/V Anna Maersk
Average vs. timemaxpFigure 38 —