Res. Agr. Eng.
Vol. 60, 2014, No. 3: 83–91
Improving performance parameters of combustion
engine for racing purposes
T. Polonec, I. Janoško
Department of Transport and Handling, Technical Faculty, Slovak University
of Agriculture in Nitra, Nitra, Slovak Republic
Abstract
Polonec T., Janoško I., 2014. Improving performance parameters of combustion engine for racing purposes.
Res. Agr. Eng., 60: 83–91.
Mechanical parts of stock engine have a performance reserve which could be utilized when the engine is used under
the race conditions. Especially normal turbocharged engines have their performance parameters designed to drive in
traffic, where a good flexibility, reliability, fuel consumption and a long service life is required. It is possible to utilize
the whole power of the engine, when changing or modifying some of its external parts and achieve better performance
parameters without modifying or changing internal engine components. Performed changes must be realized thoughtfully and on the admittable level, so the engine and other drive train components would not be damaged. In our study
we design several changes of external parts of engine which have a significant impact on the improvement of engine
performance parameters. Their contribution has been verified in practice by an engine dynamometer.
Keywords: engine; performance parameters; turbocharger; roller dynamometer
It is generally known that the engine performance is substantially dependent on the amount of
air (oxygen), which enters to the combustion chamber. Turbocharged engines are using turbochargers
or compressors to increase the amount of induced
air. The most commonly used charging system turbocharger powered by kinetic energy of exhaust
gases (Ferenc 2004; Sloboda et al. 2008; Čupera,
Šmerda 2010; Hromádko et al. 2010;).
There are several ways to increase power of turbocharged engine:
– increase of engine displacement,
– increase of turbocharger’s boost pressure and airflow,
– decrease of intake air temperature (behind turbocharger),
– reduction of mechanical and airflow losses,
– optimization of intake and exhaust manifolds,
– optimization of combustion processes by sophisticated motor-management.
The purpose is to design the best solutions to
improve the performance of normal supercharged
engine, to improve acceleration of the vehicle as
much as possible, to verify these modifications by
measurements on roller dynamometer, to assess
their contribution and propose other solutions to
achieve even better results.
Supported by the Scientific Grant Agency VEGA of the Ministry of Education of the Slovak Republic and Slovak Academy of
Sciences, Grant No. 1/0857/12 and by the Scientific Grant Agency KEGA of the Ministry of Education of the Slovak Republic
and Slovak Academy of Sciences, Grant No. 044SPU-4/2014.
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Vol. 60, 2014, No. 3: 83–91
(a)
Res. Agr. Eng.
(b)
Fig. 1. Measured vehicle (a) Fiat 127A and engine (b) Lancia 2,0 16V Turbo
MATERIAL AND METHODS
Measured vehicle. Performance measurement
was done on a special prototype vehicle designed
for a drag race (Janoško, Polonec 2011). The base
of the vehicle was bodywork of Fiat 127A (Fiat Auto
S.p.A., Torino, Italy). As the power unit Lancia 2.0
16V Turbo engine was used, which was placed in the
vehicle across, front of rear axle (Fig. 1).
The vehicle was two-door hatchback, with frameless steel body. Total weight of vehicle without driver
was 830 kg.
A powerful engine from Lancia Thema, made by
Fiat Auto S.p.A., Italy was used. It was petrol engine
with charging by turbocharger. Displacement of engine was 1,995 cm3 (bore: 84 mm, stroke: 90 mm).
Engine had 4 cylinders in-line block with 16 valve
DOHC head. Compression ratio is 8:1. Max. power of stock engine was 147 kW at 5,500 min–1 and
torque 298 Nm at 3,750 min–1.
Fuel delivery was provided by simultaneously
multi point port fuel injection, controlled by electronic control unit Bosch LE2 – Jetronic (Robert
Bosch GmbH, Gerlingen, Germany). Ignition was
fully electronic, “wasted-spark” type, controlled by
electronic control unit Magneti Marelli MED 601E
(Magneti Marelli S.p.A., Corbetta, Italy).
Calculation of suitable turbocharger. In the
calculations of suitable turbocharger we took account of future application of the vehicle in races
and we defined a max. engine power to 300 kW at
6,000 min–1. The best turbocharger for the intended
use of vehicle was calculated using the following relations (Estill 2008). Substituting the results into
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compressor maps we have chosen the best turbocharger Turbo Tech 103 (Honeywell International
Inc., Morris Township, USA).
Airflow needed to achieve the performance
target:
Qv = Pm × λ × SpSB
(1)
where:
Qv – airflow (kg/min)
Pm – performance target (kW)
λ
– air/fuel ratio (–)
SpSB – brake specific fuel consumption (kg/kW·min)
Required absolute manifold pressure to achieve
performance target:
pABS =
Qv × R × (255.6 +TP )
n
ηVOL × ×Vm
2
(2)
where:
pABS – required absolute manifold pressure (kPa)
Qv – airflow (kg/min)
R
– gas constant
Tp – intake manifold temperature (°C)
ηVOL – volumetric efficiency (–)
n
– engine speed (min–1)
Vm – engine displacement (cm3)
Compressor discharge pressure:
p2C = pABS + ΔpSTR
(3)
where:
p2C – compressor discharge pressure (kPa)
pABS – absolute manifold pressure (kPa)
ΔpSTR – pressure loss between the compressor and the
manifold (determined to 14 kPa)
Res. Agr. Eng.
Vol. 60, 2014, No. 3: 83–91
Fig. 2. Compressor map of Garrett
GT3076R turbocharger
4.5
p2C/p1C – pressure ratio of inlet and
outlet of turbocharger
4.0
3.5
p2C/p1C
3.0
2.5
2.0
1.5
1.0
0
4.5
9.1
11.3
15.9
20.4
27.2
Corrected airflow (kg/min)
Compressor inlet pressure:
p1C = pATM − ΔpSTR.S
(4)
where:
p1C
– compressor inlet pressure (kPa)
pATM – ambient air pressure (at sea level) (kPa)
ΔpSTR.S – pressure loss in air filter and piping (determine
to 7 kPa)
Pressure ratio:
∏ TD =
p2C
p1C
where:
ΠTD – pressure ratio
p1C – compressor inlet pressure (kPa)
p2C – compressor discharge pressure (kPa)
(5)
Based on calculations of operating parameters
and substituting them into various compressor
maps we chose a Garrett GT3076R turbocharger
(Honeywell International Inc., Morris Township,
USA). As seen on the compressor map (Fig. 2), this
turbocharger is the most suited to performance re-
quirements and the expected use of the vehicle for
racing purpose.
Calculation of theoretical injectors fuel flow:
Q
QP = V × ρ P
(6)
λN
where:
QP – flow of fuel (kg/min)
Qv – flow of air (kg/min)
λN – numerical value of lambda (–)
ρP – fuel density (kg/m3)
Because of lower heat stress of injectors we calculated with approximately 80% duty cycle. Considering this duty cycle RC Racing injectors with
fuel flow 750 cm3/min were chosen (at 300 kPa fuel
pressure).
Calculation of heat ratios in the intercooler
(Estill 2008).
W =U ×S×
(ΔT1 − ΔT2 ) ÷ F
⎛ ΔT ⎞
ln ⎜ 1 ⎟
⎝ ΔT2 ⎠
(7)
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Vol. 60, 2014, No. 3: 83–91
(a)
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F
(b)
T1
Tin
Tex
T2
P
Fig. 3. Heat diagram of correction factor F (a) and intercooler temperature scheme of inlet/outlet flow (b)
F – correction factor (–); P – temperature ratio (–); T1 – outside (cooling) air temperature on inlet (°C); T2 – outside (cooling)
air temperature on outlet (°C); Tin – compressed air temperature on inlet (°C); Tex – compressed air temperature on outlet (°C)
where:
W – total transfer of heat energy (J)
U – heat transfer coefficient (W/m2·K)
S
– heat transfer surface (m2)
ΔT1 – difference between intercooler input air temperature and temperature of cooling air behind intercooler (Tin – T2) (°C)
ΔT2 – difference between output air temperature from
intercooler and temperature of cooling air in
front of intercooler (Tex – T1) (°C)
F
– correction factor
Determination of the correction factor F. Correction factor F, taking into account the unequal
distribution of heat at exchanger area, could be
read from the diagram according to the calculated
values of temperature ratios of P and R (Fig. 4). For
calculation of temperature ratios P and R we need
to know temperature of compressed air (Tin, Tex)
and cooling air (T1, T2) on the inlets and outlets of
the intercooler (Fig. 3).
P=
Tex −Tin
T1 −Tin
(8)
R=
T1 −T2
Tex −Tin
(9)
where:
P, R – temperature ratios
Tex – compressed air temperature on outlet (°C)
Tin – compressed air temperature on inlet (°C)
T1 – outside (cooling) air temperature on inlet (°C)
T2 – outside (cooling) air temperature on outlet (°C)
Calculating the amount of lost or received heat
on one side of exchanger:
W = Qm × C P × ΔT
(10)
where:
W – heat energy transfer (J)
Qm – mass airflow (kg/min)
Cp – heat capacity of air (J/K·mol)
ΔT – difference of input and output temperatures (K)
T2
Tex
Fig. 4. Airflow through the intercooler
Tin
T1
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T1 – outside (cooling) air temperature on inlet;
T2 – outside (cooling) air temperature on outlet; Tin – compressed air temperature on inlet;
Tex – compressed air temperature on outlet
Res. Agr. Eng.
RESULTS AND DISCUSSION
Performed engine modifications
The engine power can be measured by the dynamometer directly or through the power take-off
shaft, or possibly on a roller bench or by the roadboard test (Semetko, Janoško 2005). After performance measurement of stock engine the following modifications were made:
Stage 1:
– turbocharger replaced by more powerful type
Garrett GT3076R, with rotor on ball bearings,
– injectors replaced by more powerful (RC Racing;
RC Engineering, Inc., Higgins Court Torrance,
USA) with fuel flow 750 cm3.min (at fuel pressure 300 kPa),
– shortened exhaust system, removed mufflers,
– modified of sensing airflow by electronic control
unit,
– intercooler placed in the box enabling cooling by
ice,
– boost pressure controlled by manual boost controller.
Stage 2:
– stock electronic control units replaced by fully
programmable unit VEMS ver. 3.6 (Acmv LLC,
Wilmington, USA),
– intercooler replaced by “water to air type” with
cooling by circulated water,
Vol. 60, 2014, No. 3: 83–91
– intake manifold replaced by shorter type from
Lancia Kappa,
– throttle body replaced by bigger one with internal diameter 73 mm,
– stock exhaust manifold replaced by custom steel
manifold with pipes with diameter 42 mm,
– boost pressure controlled by electronic control
unit with solenoid valve.
Dynamometer
The measurements were performed on the roller dynamometer MAHA LPS 3000 PKW 4 × 4
(MAHA Maschinenbau Haldenwang GmbH & Co.
KG, Haldenwang, Germany) (Fig. 5).
Parameters of dynamometer MAHA LPS
3,000 PKW:
– max. measurable output: 520 kW (4 × 4 version),
– max. measurable torque: 1,000 Nm,
– accuracy: +/– 2%,
– conversion of measured parameters according to
technical norms.
Procedure of measuring power and torque
on dynamometer
The vehicle will start to gradually speed up to
50 km/h, on penultimate gear. Then depress accelerator pedal to maximum and watch the course of
performance on monitor up to reach a max. engine
Fig. 5. Positioning vehicle on
dynamometer MAHA LPS
3,000 PKW
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Res. Agr. Eng.
239.0
375
191.2
300
143.4
225
95.6
150
47.8
75
0
M (Nm)
P (kW)
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0
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
n (min–1)
Performance data
Corrected power
Engine power
Wheels power
Power losses
Torque
Max. torque at
Max. rpm
External data
Pnorm
142.3 kW
Air temperature
15.5°C
Pmot
141.6 kW
Aspirated air temperature
19.1°C
Pkolo
107.7 kW
Relative air humidity
Pztráty
34.6 kW
Air pressure
Mnorm
292.5 Nm
n
Vapour pressure
–1
55.4%
1,008.0 hPa
9.8 hPa
3,905 min
Oil temperature
126.1 km/h
16°C
6,120 min–1
Fuel temperature
197.6 km/h
–
Fig. 6. Measurement of power and torque before engine modifications
speed. When max. speed is reached, the technician pushes the clutch pedal and simultaneously
releases accelerator pedal. The wheels are left free
to catch up to 0 km/h. Dynamometer now records
power loss. The waveform of power, torque and
losses are saved to the memory of dynamometer.
However, the measured values of power and torque
were not significantly different from the manufacturer’s values. Max. measured power [adjusted according to DIN 70020 (1993)] was 142.3 kW and
torque was 292.5 Nm (Fig. 6).
Measurement No. 1 – Stock engine
Measurement No. 2 – First level
of modifications
First measurement was used to determine the
initial state. Engine with stock technical specifications without any performance modifications was
installed in vehicle. Intake air temperature (in front
of air filter) according to the testing laboratory was
19.1°C, relative humidity 55.4% and atmospheric
pressure 1,008 hPa.
During the verification measurements slightly
lower max. values, than those declared by manufacturer were recorded, but this was attributable to
higher mileage and therefore wear of the engine.
The second measurement was performed after the
“Stage 1” of engine modifications (see “Performed
engine modifications” section). Conditions of measurement were almost unchanged. According to the
testing laboratory intake air temperature (in front
of air filter) was 18°C, relative humidity was 56.6%
and the atmospheric pressure was 1,007.9 hPa. Intercooler was cooled by ice with the temperature of
approx. 0°C. As it is seen on the graph of the second measurement (Fig. 7), the recorded power was
210.2 kW and the torque was 400.3 Nm. An increase
88
367.8
500
294.2
400
220.7
300
147.1
200
73.6
100
0
0
0
1,000
2,000
3,000
4,000
n (min–1)
Performance data
Corrected power
Engine power
Wheels power
Power losses
Torque
Max. torque at
Max. rpm
M (Nm)
Vol. 60, 2014, No. 3: 83–91
P (kW)
Res. Agr. Eng.
5,000
6,000
7,000
External data
Pnorm
210.2 kW
Air temperature
15.5°C
Pmot
209.5 kW
Aspirated air temperature
19.1°C
Pkolo
171.1 kW
Relative air humidity
Pztráty
38.4 kW
Air pressure
Mnorm
400.3 Nm
n
55.4%
1,008.0 hPa
Vapour pressure
9.8 hPa
4,130 min
133.4 km/h1
Oil temperature
16°C
6,330 min–1
204.5 km/h
Fuel temperature
–
–1
Fig. 7. Measurement of power and torque after “Stage 1” engine modifications
of performance over the first measurement was
67.9 kW and an increase of torque was 107.8 Nm.
This increase of power and torque was affected
mainly by mechanical modifications of external
parts of engine, exchange of turbocharger with a
more powerful one and an increase of intercooler
cooling efficiency.
Measurement No. 3 – Second level
of modifications
The third measurement was performed after
“Stage 2” engine modifications (see “Performed engine modifications” section). According to the testing laboratory intake air temperature (in front of air
filter) was 22.3°C, relative humidity was 33.7% and
atmospheric pressure was 982.4 hPa. As it is shown
in the graph of the third measurement (Fig. 8), there
is one more shape (grey colour), which shows the
boost pressure level. Since using new engine elec-
tronic control unit, we were able to control the boost
level with electronic control unit and solenoid valve.
Max. boost pressure was now set to 1.6 bar, but because we wanted to protect transmission system
against high torque peaks, boost pressure was increased slowly from 1 bar (at approx. 4,000 rpm) to
1.6 bar at max. engine speed. This allowed driver to
utilize engine max. power and torque in high revolutions, which is very useful in race conditions.
Max. measured power (adjusted according to
DIN 70020 (1993)) was 310.7 kW and torque was
457.9 Nm. Increase of performance over the previous (Stage 1) measurement was 100.5 kW and increase of torque was 57.6 Nm. But more interesting is
the increase of max. power over stock engine, which
was 168.4 kW and for max. torque it was 165.4 Nm.
In percentage, it is an increase of more than 118% of
max. power and more than 56% of max. torque.
This increase of power and torque mechanical modifications of intake and exhaust system,
exchange of intercooler and also exchange of the
89
Res. Agr. Eng.
367.8
500
294.2
400
220.7
300
147.1
200
73.6
100
0
M (Nm)
P (kW)
Vol. 60, 2014, No. 3: 83–91
0
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
–1
n (min )
Performance data
Corrected power
Engine power
Wheels power
Power losses
Torque
Max. torque at
Max. rpm
External data
Pnorm
310.7 kW
Air temperature
20.5°C
Pmot
300.1 kW
Aspirated air temperature
22.3°C
Pkolo
256.3 kW
Relative air humidity
Pztráty
43.8 kW
Air pressure
Mnorm
457.9 Nm
n
–1
Vapour pressure
8.1 hPa
Oil temperature
19°C
6,470 min
202.8 km/h1 Fuel temperature
–1
6,495 min
Manifold air pressure (hPa)
203.6 km/h
Fig. 8. Measurement of power and torque after “Stage 2” engine modifications
Fig. 9. Modifying and logging data in programme VemsTune
90
33.7%
982.4 hPa
–
Res. Agr. Eng.
Vol. 60, 2014, No. 3: 83–91
stock electronic control units by fully programmable unit, allow us to optimise all necessary control
parameters of ignition timing and fuel injection.
Tuning of electronic control unit
At the first and second measurements, engine
was controlled by stock control units only with
modified airflow sensing system for adjusting the
correct air/fuel ratio at all driving conditions.
Before measurement No. 3, we installed new,
fully programmable electronic control unit VEMS.
This unit allowed us to modify all necessary data
to tune up main control parameters of the engine.
Modification of the parameters is possible in real
time, without stopping the engine or disconnecting
control unit. Tuning was done in the official computer programme VemsTune (Acmv LLC, Wilmington, USA), which allowed us to change engine
management parameters and also to log actual data
from all engine sensors (Fig. 9).
CONCLUSION
This paper presents some options and methodology for upgrading the turbocharging and fuel
injection system to increase engine power, which
can also be used (with some modifications) in other types of turbocharged transport and agriculture
vehicles to increase their dynamical parameters or
working efficiency.
From the measured values it can be seen what
benefits to an increase of the engine performance
parameters modifications of engine components
performed. During the measurements, we found an
increase of the max. engine power, compared to the
serial status, up to 168 kW and max. torque up to
165 Nm. This increase is mainly due to an exchange
of turbocharger for a more powerful one, optimising
thus intake and exhaust manifolds and optimising
the fuel and ignition system for new engine setup.
Since we designed the turbocharger to be able to
supply the necessary amount of air to the engine
power up to 300 kW and engine is currently reaching
more than 310 kW, we reached our goal. The manufacturer recommended this type of turbocharger also
for engines with power more than 400 kW, but if we
want to maintain the reliability at this high performance level, it will be necessary to exchange all internal components of engine by stronger, high quality
forged parts in future. Next step must be modification
of the transmission system and clutch, because now
these parts are on their performance peaks.
To achieve higher performance parameters of the
engine in future, it will be necessary to set up boost
pressure of turbocharger to higher level, upgrade
camshafts and also to upgrade the fuel system.
References
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für Normung e. V.
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[Determination of Tractor΄s Parameters.] Nitra, ES SPU.
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Received for publication May 22, 2012
Accepted after corrections September 20, 2012
Corresponding auhtor:
Doc. Ing. Ivan Janoško, CSc., Slovak University of Agriculture in Nitra, Technical Faculty,
Department of Transport and Handling, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic
phone: + 421 37 641 4114, e-mail:
[email protected]
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