Transport technic and technology
Volume XV Issue 1 Year 2019
ASSESSING THE IMPACT OF USING FUELS MADE FROM VEGETABLE OIL
ON SELECTED OPERATIONAL VEHICLE CHARACTERISTICS
Abstract. Vegetable oil based fuels significantly enable reducing the costs of fuel purchased. CI engine vehicles with
rotary and inline injection pump can be fuelled by vegetable oil based fuels instead of being fuelled by diesel. This is
very common, since their price is lower in comparison with diesel. The article focuses on the impact of using fuels
made from vegetable oil on selected vehicle characteristics in particular conditions. It includes the measurements of
the impact of using fuels such as FAME, fresh oil and used oil on the engine smoke opacity, content of selected
emissions in the exhaust gases as well as on the engine power and torque’s course. The measurement results are
mutually compared with the results measured when using diesel. In order to secure the measurements to be
repeatable, they were performed in laboratory at the cylinder test station MAHA MSR 1050. The vehicle tested
during its last 100,000 kilometres driven by vegetable oil based fuel has been selected for these measurements.
Therefore, by these measurements, it was also possible to assume partially the impact of long-term using aforesaid
fuels on selected vehicle characteristics.
Keywords: emissions, FAME, fuel, engine power, vegetable oil,
1 Faculty of Operational and Economics of Transport and Communications, University of Žilina,
Univerzitná 1, Žilina, +421 41 513 3518, email@example.com
2 Faculty of Operational and Economics of Transport and Communications, University of Žilina,
Univerzitná 1, Žilina, +421 41 513 3523, firstname.lastname@example.org
3 Faculty of Operational and Economics of Transport and Communications, University of Žilina,
Univerzitná 1, Žilina, +421 41 513 3518, email@example.com
4 Faculty of Operational and Economics of Transport and Communications, University of Žilina,
Univerzitná 1, Žilina, +421 41 513 3532, firstname.lastname@example.org
Most of the costs for an operation of vehicle are
those of purchases of fuel (Synák, 2019). Part of the
owners of agricultural machineries and tractors as well as
vehicles with CI engines reduces the costs of fuel
purchased by using fuels produced on the basis of
vegetable oil. These include oils such as FAME, fresh
vegetable oil and used vegetable oil (Mohadesi et al.,
FAME, i.e. fatty acid methyl ester, is a fuel of
natural origin. It can be made from used vegetable oil by
removing glycerol molecule. This is further followed by
transesterification of fats with methanol. The production
of FAME is also possible at home. The price per litre of
FAME depends specially on the vegetable oil’s purchase
price. Production costs of FAME made from 1 litre of oil
used are approximately of 0.13 € (Karimi et al., 2016).
Fresh oil represents an oil of natural origin made
from sunflower or oilseed rape. The vegetable oil can be
bought from about 0.70 €/l (komodityonline). It is not
processed in any way before being used in a vehicle.
Used oil represents a type of oil used when cooking
meals, most often when frying. It is necessary to be
filtered through a sieve or gauze before being used in a
When comparing the costs of diesel fuel and fuels
made from vegetable oil, it leads the drivers to use fuels
made from vegetable oil (globalpetrolprices).
The purpose of this article is to compare the impact
of using selected fuels made from vegetable oil and diesel
on several aspects of vehicle operation under specific
conditions. The article contains the results of measuring
the impact of fuels made from vegetable oil on the engine
smoke opacity, exhaust gases volume composition from
the harmful emissions point of view and, on the course of
the engine power and torque’s curves depending on the
engine speed. Each of the measurements was performed
with using diesel fuel, FAME, fresh vegetable oil and
Since the engine smoke opacity is regularly
measured during a vehicle inspection, it is also measured
in this article. Therefore, the purpose is to determine
whether a vehicle fuelled by selected fuel meets the
requirements for smoke opacity value that is verified
during vehicle emission inspection.
Exhaust gases volume from the emission point of
view focuses on the presence of CO, CO2, HC and NOx.
CO, i.e. carbon monoxide, is produced from the
partial oxidation of carbon. CO has an adverse effect on
human health. It binds with haemoglobin 300 times
stronger than oxygen, and so it prevents oxygen from its
transfer from lungs into organism. CO has a share in
increasing premature mortality of population (Šarkan et
CO2, carbon dioxide, is a greenhouse gas. Its share
in the greenhouse effect is more than 50 % (Škorupa et
UHCs, unburned hydrocarbons, are products of
incomplete combustion of fuel in an engine.
Hydrocarbons irritate the human mucous membranes and
some of them are carcinogenic (Shim et al., 2018).
NOx, nitrogen oxides, are produced in the engine
combustion area at higher pressures and temperatures.
These conditions are fulfilled mainly by CI engines
(Synák et al., 2018). Nitric oxide (NO), nitrogen dioxide
(NO2), nitrous oxide (N2O) together with dinitrogen
trioxide (N2O3) and dinitrogen pentoxide (N2O5) are
produced during the period at which an engine works in
the above mentioned conditions. NOx have adverse
effects on human health as well as on the greenhouse
effect. They also cause acid rain (Skrúcaný et al., 2018).
In order to start measuring, a vehicle with CI engine
fuelled its last 100,000 kilometres by vegetable oil based
fuel has been chosen. By measuring the engine power and
torque, it was possible to find out whether the engine can
have a power and torque prescribed by the manufacturer.
1. Measurement methodology
The measurements included measuring the smoke
opacity, exhaust gases volume and the course of the
engine power and torque. Each of the measurements was
made with using diesel, FAME, fresh vegetable oil and
waste vegetable oil.
The measurements were performed with Mercedes
300 D 124 W, a vehicle with inline fuel pump and
indirect fuel injection. The construction scheme of fuel
system is shown in Fig. 1.
Fig. 1 Inline fuel pump (Janoško et al., 2010)
A fuel is transported via feed pump from the fuel
tank trough fuel filters into the high pressure inline fuel
pump. Here, the fuel is pressed down to the pressure of
about 12 MPa and it is further transported through the
high pressure pipes into injectors. These secure a fuel
distribution in the distributor pumps. Superfluous fuel is
returned back to the fuel tank. In order to prevent
particular fuels from being mixed during the
measurements, the fuel was transported by fuel can
instead of fuel tank, see Fig. 2.
Fig. 2 Fuel can
This way of fuel drawing from a can prevents the
measured fuel from being mixed with the others.
The process of fuel replacing was as follows:
• Fuel pump hose was put into to the can with fuel
prepared for measuring,
• Hose with superfluous fuel was put into another
• Bleeding of fuel system, starting of engine,
• Can was filled up by piping with superfluous
fuel of minimum 2 litre volume,
• Return line piping was shifted into the can with
fuel prepared for measuring.
Pumping of superfluous fuel from the previous
measurement was secured by putting the return line hose
into another can. At the same time, only new fuel
prepared for particular measuring was transported into the
whole fuel system.
Each fuel replacing has the same process.
1.1. Smoke opacity measurement
Smoke opacity was measured by MAHA MDO2 –
LON V 6.11. by free acceleration method. It was
measured by the opacimeter that works on the optical
principle – the exhaust gases are illuminated by a light,
when the value of smoke opacity measured relates to the
value of light absorbed.
The method of free acceleration lies in measuring the
smoke opacity during the time when a pedal is fully
applied up to 1 second, i.e. a full fuel amount is reached.
Acceleration pedal is released after the maximum engine
speed has been achieved and recorded. The process is
repeated 3 times. After that, the arithmetic mean is
calculated from the values measured (Kralik, 2019).
1.2. Exhaust gases composition measurement
Exhaust gases composition was measured by
MAHA MGT 5. The components measured were CO,
HC, CO2 and NOx. The measurements were performed
during simulating a vehicle driving on the cylinder power
test station MAHA MSR 1050 at the driving speed of 50
km.h-1 and 90 km.h-1. The accuracy of test station’s
measuring is ±2 % (Šarkan et al., 2017). There was used
the first gear at both speeds.
Firstly, for a drive simulation, it was necessary to
calculate the value of vehicle driving resistances by
which the cylinders were braked. Since there was a plane
drive at the constant speed chosen, the engine must have
overcome the rolling and the air resistances. The value of
rolling resistance has been calculated according to
Fr = m .g . f
Fr – value of rolling resistance [N]
m – vehicle mass [kg]
g – gravitational acceleration [m.s-2]
f – rolling resistance coefficient [-] (Radosavljevic
et al., 2019)
Having the mass of the vehicle in running order of
1,440 kg, the rolling resistance coefficient of vehicle
tyres 0.008 has the value of 113 N.
The value of air resistance has been calculated
according to the relation:
Fa = 0,5 . v2 . cx . S .
Fa – value of air resistance [N]
v – driving speed [m.s-1]
cx – air resistance coefficient [-]
S – size of front face [m2]
ρ – air density [kg.m-3] (Skrúcaný et al., 2016)
Having the speed of 50 km.h-1 and the air density
of 1.29 kg.m-3, the value of air resistance is 77 N. It is
250 N when having the speed of 90 km.h-1.
The calculated values of driving resistances were
entered into the cylinder test station computer. The
cylinders were subsequently braked by the same value.
The measurement of the exhaust gases composition
was performed after the vehicle had been stabilized at the
required speed. The driving speed was observed with
deviation of ± 0.5 km.h-1.
1.3. Measurement of the course of the engine power
and torque’s curves
The measurements were performed at the cylinder
test station MAHA MSR 1050 respecting the fourth
transmission gear. The vehicle was fixed on the test
station and after the engine had been conditioned at the
fourth gear with having the acceleration pedal fully
applied, the maximum engine speed was reached and,
thus, the engine power was measured. After that, a driver
applied the clutch pedal when still using the fourth gear,
and let the wheels slow down freely in order to measure
the mechanical losses between the engine and cylinders.
Then the computer calculated the course of the engine
power and torque’s curves (MAHA MSR).
2.1. Engine smoke opacity
The Table 1 shows the measured value of engine
smoke opacity depending on the fuel used. The first
column shows the fuels used during measurements. The
second column displays the value of smoke opacity and
the third column displays the difference of smoke opacity
measured in % compared with diesel. The last column
shows the value of variance which is calculated as the
arithmetic mean of deviations between the measurements.
Table 1 Engine smoke opacity depending on the fuel used
Change in the
with diesel %
- 23.4 %
- 37. 5 %
- 40.6 %
The graph in the Figure 3 also shows the results for its
Fig. 3 Engine smoke opacity depending on the fuel used
As seen from the Table 1 and Figure 3, the highest
value of smoke opacity was reached during diesel
measurement. By using waste oil, the engine smoke
opacity reduced up to 40.6 % in comparison with diesel.
2.2. Exhaust gases composition
The following part of the article shows the impact of
the operation of vehicles fuelled by diesel, FAME, fresh
and waste oil on the exhaust gases volume in the engine.
The table 2 displays the impact of using particular fuels
on the values of CO and CO2. The results are matched to
the driving speeds when being measured.
Table 2 HC and NOx concentrations in the exhaust gases
For better transparency, the values of HC
concentration are shown in the form of graph, see Fig. 6
Fig. 4 Values of HC concentration in the exhaust gases
When using fuels made from oils, HC concentration
The Fig. 7 shows the values of NOx concentration in
the exhaust gases depending on the fuel used.
Fig. 5 Values of NOx concentration in the exhaust gases
When using oil based fuels, NOx concentration in the
exhaust gases decreased.
2.3. Engine power and torque courses
The impact of the fuel used on the engine power and
torque is shown in the Fig. 8. The graph’s horizontal axis
displays the engine speed in min-1, its left vertical axis
shows the engine power in kW, and its right vertical axis
shows the engine torque in Nm. Orange flatter curves
represent the course of torque, and red steeper ones
represent the course of the engine power. The course of
power´s curves on the cylinder test station are in blue,
and, between the engine and cylinders are in green.
Fig. 6 Impact of fuel on the engine power and torque’s courses
As seen from the Figure 8, it can be said that all of
the courses are mostly the same. Over the whole
measurement, the highest power is seen when using
diesel. When using fresh oil, the course of the engine
power and torque was lower. When using FAME and
waste oil, the curve course was almost identical taking
into consideration the deviations of MAHA MSR 1050.
The biggest difference in the engine torque was measured
when using diesel and FAME at the speed of 1,800 min-1
- 12 Nm, power of 5 kW, and the engine speed of 4,200
To understand the impact of fuels used on the
vehicle acceleration better, it is possible to make a
theoretical calculation of maximum acceleration with
using the first gear. The engine torque is important for a
maximum possible value of vehicle acceleration. The
calculation is therefore made by taking into consideration
the engine speed at which the biggest difference of engine
torque had been measured.
The first step is to determine the wheel force
according to relation:
Fw = (Mt . ic .
m) / rd
Fk - the wheel force [N]
Mt - the engine torque [Nm]
Ƞm - the mechanical transmission efficiency
rd - the wheel radius [m] (Radosavljevic, 2019)
The engine torque measured at given speed with
using diesel is 162 Nm, see Fig 6. The overall
transmission ratio when using the first gear is given by
ic = iI . ir
ic - the overall transmission ratio [-]
iI - the transmission ratio at the first gear [-]
ir - the constant transmission ratio in the transfer case
[-] (Rievaj et al., 2014)
The value of transmission ratio at the first gear is
according to (cars-data) 3.86 and, in the transfer case it
is 3.46. The overall transmission ratio at the first gear has
ic = 3.86 . 3.36 = 13.36
The vehicle has got tyres with size of 195/65 R 15.
The wheel radius is:
r = [2 .(195.0.65) + (15 . 25.4)] : 2 = 371.3 mm
The wheel force is:
Fw = 162 . 13.86 . 0.90 / 0.37 = 5246.13 N
The maximum possible value of resistance against
the acceleration can be calculated using relation:
Fa = Fw
Fa = 5246.13
113 = 5133.13 N
Then the maximum vehicle acceleration can be
amax = Oa/m .
a is the vehicle acceleration [m.s-2]
Oa is the maximum possible value of resistance
against the acceleration
m is the vehicle mass
δ is the rotational mass coefficient (Synák, 2019)
The calculation of the rotational mass coefficient is
time demanding and requires identification of mass and
radius of every single rotational component in the engine,
between the engine and wheels and between the wheels
themselves. In this case, there is no need for so high
measurement accuracy. The coefficient value for
calculation with using both, diesel and FAME is δ = 1.45,
according to .
The possible vehicle acceleration with diesel used:
amax = 5133.13/1440 . 1.45
= 2.46 m.s-2 (11)
The maximum theoretical vehicle acceleration when
using diesel at the engine speed of 1800 ot.min-1 with the
first gear used is 2.46 m.s-2. By analogical calculation, it
is possible to determine that when replacing diesel with
fame, under these conditions, the vehicle can have the
acceleration of 2.27 m.s-2. The theoretical difference of
vehicle acceleration when using diesel and FAME is 0.19
Using of vegetable oil based fuels does affect the
engine smoke opacity, the exhaust gases composition as
wells the course of the engine power and torque for little.
The value of smoke opacity measured when using
diesel fuel has reached the value of 0.64 m-1, while the
maximum permissible value of smoke opacity is 2.50 m-1.
Therefore, the engine is able to meet the prescribed
emission limits of smoke opacity also after having tested
its last 100,000 of kilometres driven. The value of engine
smoke opacity also shows the condition of engine and its
parts, for example the degree of wear of piston rings,
movable components in the injections, and the elements
in high pressure pump (Yesilyurt, 2019). In case of these
parts being worn out extremely, it could lead to wrong
fuel dispersion, or to combustion of engine oil with a
fuel, and thus the values of smoke opacity would be
substantially higher (Figlus et al., 2016).
The measurements have shown a significant reduction of
smoke opacity by using fuels made from vegetable oil.
Thus, the vehicle is capable to meet the requirements
imposed on the smoke opacity during the regular vehicle
inspection even when using vegetable based fuels.
Using of fuels made from vegetable oil has also had
a significant impact on the exhaust gases composition.
CO, CO2 and HC concentrations when using these fuels
have increased in comparison with the values measured
when using diesel oil. NOx concentration has decreased
when using vegetable based fuels. A possible explanation
of such changes in particular exhaust gases components
concentrations is that there is a different length of
hydrocarbon chain of particular fuels and, probably,
the lower heating value of fuels, too (Chand, 2002). Out
of these, it can also be concluded the different
composition of fuels. While diesel composition is
regularly inspected, the other fuels are not. Thus, the
composition of vegetable oil based fuels may always vary
greatly or little.
When determining the impact of using selected fuels
on the course of the engine power and torque curves, the
impact of wear was small, even negligible. The highest
values of engine power and torque were measured when
using diesel, and then with fresh oil and waste oil. The
lowest values were measured with FAME used. However,
the differences were minimal. The low impact of fuels on
vehicle dynamics was also proven by calculation of
maximum theoretical vehicle acceleration. Its difference
is hardly to recognize, especially from the driver’s point
of view, bearing in mind that the difference can be only
seen in the narrow range of engine. The cylinder test
station MAHA MSR 1050 also provides a function of
measuring the dynamic vehicle acceleration. However,
there is no possibility to measure the difference in
maximum theoretical acceleration, since the different
course of the engine power and torque curves was only in
that narrow range of engine speed. When having
the acceleration pedal fully applied, the engine speed
would have been quickly overcome, and, thus, the
acceleration would not have been able to measure.
Representing the calculation of possible vehicle
acceleration proves that using selected fuels will not
cause the deterioration in dynamic vehicle characteristics
when having an acceleration pedal fully applied.
This article was created to support project named as:
VEGA no. 1/0436/18 - Externalities in road transport, an origin,
causes and economic impacts of transport measures.
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