Computer-Aided Design and Development of a Cylinder Head

COMPUTER-AIDED CYLINDER HEAD DESIGN AND DEVELOPMENT
ADITYA SRIPATHI VENKATA, CH.KIRAN KUMAR REDDY AND G.V. SATYA PRAKASH
TEAM FORCE INDIA
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ABSTRACT
The Automotive industry of today is a very
modern, robust and efficient field of
engineering. Through the years from its
inception in the 1930’s, the industry has
expanded massively bringing along with
itself, a multitude of technological changes
and inventions. These changes focussed on
improved driveability, increased vehicle
performance and to provide high levels of
comfort to the user. Various design changes
and developments are made to the heart of
the vehicle i.e. the engine and its parts to
improve the torque, power, and the fuel
efficiency. The performance of any engine
is based largely on the quantity and quality
of air flowing into the combustion chamber.
Promoting better air flow means the
engines breathes well and performs better.
Therein lies the core of this research project
work i.e. designing and developing the
Cylinder Head modifications using
engineering techniques and computer-aided
software programs.
The focus of this project lies at carrying out
research work on a Briggs & Stratton
Animal 206 engine’s cylinder head.
Evaluating the stock head, its air flow
numbers, deciding on modification factors
by designing the intake port, performing a
C.A.E. Simulation of the stock port are
included in the basic study. The
modifications done on the cylinder head
based on the Simulation results, evaluating
the performance increase by testing the
modified cylinder head and testing the head
on the engine dynamically are defined as
the research process of the project. The
conclusion of this project report
demonstrates the effect of the modifications
performed and its applications in real life
performance and fuel efficiency
improvements of the engine.
INTRODUCTION
Air is a fluid which is responsible for the
combustion of fuel in the combustion
chamber. This combustion of the fuel-air
mixture in turn causes a force to be exerted
on the reciprocating parts of the engine. The
force produced is the torque that is
transmitted via the crankshaft to the
driveline thus propelling the vehicle. Air
flow is the primary factor which either
reduces or boosts the performance and
efficiency of the engine. The technique of
modifying the, intake manifolds, intake
ports and cylinder heads is called as
cylinder head porting. Cylinder head
porting is done to help the engine to breathe
better and thereby produce greater output
by consuming lesser fuel. The
fundamentals of porting are to increase the
quantity of air, promote better swirl
characteristics and increase the velocity of
the air moving through the intake of the
engine. The swirling movement of air
causes the fuel-air mixture to mix properly
and combust efficiently. The quantity of air
and its velocity help in increasing the
compression ratio of the engine. Thus,
effectively ported cylinder heads produce
better air flow and improve the efficiency
of the engine and the driveability of the
vehicle.
OBJECTIVES AND GOALS
The objectives of this project include:
1. Studying and Analysing the stock
Cylinder Head and Engine.
2. Utilization of Computer-Aided Tools to
design modifications and simulate results.
3. To modify the cylinder head on the basis
of simulated results.
4. Verify results by dynamic testing.

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STOCK CYLINDER HEAD AND
ENGINE DESCRIPTION
The stock cylinder head that was used for
the project is from a Briggs & Stratton IC
206 Animal Engine. The engine in itself is
used for a multitude of purposes ranging
from small scale applications to racing. The
Animal 206 [1] is a single cylinder
carburetted engine with the model number
124332. It has a displacement of 12.48
Cu.in or 206 cc, a compression ratio of
8.5:1, a bore diameter of 2.6885 in, a
stroke length of 2.2 in and a power output
of 6 HP.
The stock Cylinder Head [2] is a casted
type head with the part number being
555635. It features a race inspired intake
port with 3-way valve retainers and high-
silicon valve springs. It also has a nitrited
dished exhaust valve along with a Fire-
Ring Head Gasket. The Intake valve
diameter was .925” and the Exhaust valve
diameter was 0.875”. The Animal 206
engine is illustrated below.
Fig. 1. Picture of the Animal 206 Engine.
STOCK TEST RESULTS AND
ANALYSES
INTAKE
The stock cylinder head was mounted onto
an SF-60 Flow bench. Attached to the flow
bench was a swirl meter that was used to
record the swirl values of the intake air
flow. The cylinder head was flowed at a test
pressure of 15” of 𝐇 𝟐 𝐎. The stock head was
tested at a test temperature ranging from
94.7⁰F to 101.4⁰F and Flow Temperature
ranging between 74.0⁰F and 78.9⁰F. The
Barometric Pressure and Relative
Humidity conditions at the time of testing
were 27.91” of Hg and 26% respectively.
The intake valve flowed 10.35 CFM of air
at the first lift point, and 26.87 CFM of air
at peak lift. A peak swirl value of 2330
RPM was recorded on the swirl meter. The
figure below illustrates the intake flow table
and graph. (Refer Appendix A)
Fig. 2. Intake Air Flow Table.
Fig. 3. Intake Air Flow Graph.

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EXHAUST
In addition to the intake, the exhaust valve
side was also flowed at the same test
conditions. The peak air flow recorded was
26.58 CFM at peak lift. The figures below
illustrate the exhaust flow table and graph.
Fig. 4. Exhaust Air Flow Table.
Fig. 5. Exhaust Air Flow Graph.
The stock test results provided vital
information about the cylinder head. The
conclusions that were derived from the
testing were that the peak air flow could be
improved significantly and that the air mass
swirl could also be increased to a greater
number. On observation, the cylinder head
had sharp edges and the port area near the
short side radius was significantly large [3].
Hence, with these observations in place
Computer-Aided Tools were used to design
and simulate modifications. The next
section deals with the process of using CAD
and CAE to determine possible design
solutions and their simulated outcomes.
COMPUTER-AIDED DESIGN AND
SIMULATION ANALYSES
COMPUTER-AIDED DESIGN
The most important part of this project was
to use Computer-Aided Design and
Computer-Aided Engineering to design
the modifications and to simulate and
analyse results in unison with the design
changes. The goal was to maximize the
intake air flow and hence, the first step was
to design the stock intake port using CAD
followed by adding modifications to the
design in order to improve the quality of air
and the quantity of air flow.
1. STOCK PORT DESIGN
The software used to design the intake port
was PTC CREO v2.0. The intake port on
the cylinder head was filled with a mould
substance and a mould of the intake port
was extracted. This mould was used to
measure the intricate dimensions of the
intake port on the short-side radius, the
valve guide area and the valve seating
area. The design of the intake port is
illustrated as follows.
Fig. 6. Stock Intake Port Design.

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2. MODIFIED PORT DESIGN
The intake port modification process was
based on the ideas derived from the S.A.E.
Paper named “Cylinder Head Intake
Flow Analysis” [4] published by the
authors Jawad, B. and Arslan, S. The idea
involves the maximization of the area of the
inlet port at the opening and necking it
down towards the short-side radius. Also,
the focus is placed on the roof of the inlet
port as the air flow is maximum. Thus, the
modified port design included the filling up
of the floor of the port and causing an
upward movement of air flow towards the
roof. The CAD Design was then
implemented as shown in the figure below.
Fig. 7. Modified Intake Port Design.
The modified port design was completed
and the next step in the process was to
simulate the air flow through the port. The
simulation process helps in understanding
the differences between the stock and
modified results without the need of
making any actual changes to the cylinder
head. The next section deals with the CAE
simulation of the stock and the modified
intake port respectively.
COMPUTER-AIDED SIMULATION
The CAE Simulation [5] of the intake port
included the analysis of the intake air flow
velocity gradient, its vector flow, scalar
flow and its swirl characteristics. The tool
used for the simulation was STAR CCM +
v 9.0. The steps included in each of the
simulation procedures were to create a
parasolid of the CAD Design, to create a
velocity inlet and a pressure outlet, assign
individual values, mesh the parasolid and
create a scalar and vector scene. A
residuals plot of 500 iterations was
performed to estimate the air flow with
consistency.
1. STOCK PORT SIMULATION
The stock intake port having flown 26.87
CFM of air on the flow bench was
simulated for air flow. The velocity of the
air in the scalar flow scene was 0 m/s at
minimum and 336.59 m/s at peak. In the
vector flow scene, the velocity of air was
31.690 m/s at minimum and 361.92 m/s at
peak. The results of the stock intake port
are illustrated as follows. (Refer Appendix B).
Fig. 8. Stock Port Flow Velocity.

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2. MODIFIED PORT SIMULATION
The modified port was simulated for air
flow and it produced significantly better
results in comparison to the stock intake
port design. The flow velocity in the scalar
flow scene increased to a peak of 401.33
m/s from the original 336.59 m/s which is
effectively a 19.23% increase. In the
vector flow scene, the velocity of air
improved from 31.690 m/s to 40.801 m/s at
minimum which implies a 28.75%
increase. At peak velocity levels, the
increase in velocity was from 361.92 m/s to
432.62 m/s resulting in an increase of
19.53%. This increase in velocity when
tuned precisely, leads to a good swirl which
helps the fuel-air mixture to mix properly
and increases the fuel efficiency of the unit.
[6] The figure below represents the velocity
flow gradient of the modified intake port.
(Refer Appendix C).
Fig. 9. Modified Port Flow Velocity.
The improvements were recorded across all
lift ranges and a significant rise in air flow
was recorded across all points. Thus, with
the simulation being completed, the
modifications could now be implemented
onto the cylinder head.
MODIFICATIONS PERFORMED
The simulated head design included the
alteration of the shape of the port. The
theoretical results had been confirmed by
the simulated results. Hence, one of the
major modifications that was performed on
the intake port was to fill up the floor and
the side walls with clay to cause an
upward displacement of the air towards
the roof of the port. [7] This upward
displacement meant that the velocity would
increase causing greater swirling
movement of the air.
In addition to this, as discussed earlier, the
air movement was being restricted by sharp
edges in many parts of the intake port. To
eliminate this, the cylinder head was fixed
onto a clamp and the sharp edges on the
short-side radius, valve seating area and
the valve guide area were smoothened out.
[8][9][10] The tools that were used were
carbide cutters and sand papers. The
intake area was expanded to facilitate the
allowance of larger quantity of air into the
port. The area of the port near the short side
radius was necked down slightly in order to
promote greater swirl. The modified port is
illustrated in the picture below.
Fig. 10. Modified Intake Port.
In addition to this, the exhaust port was also
smoothened to allow the exit of hot exhaust
gases at faster rates and in smooth fashion.

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MODIFIED TEST RESULTS AND
ANALYSES
INTAKE
The modified cylinder head was flowed on
the flow bench. The head was tested at a
test temperature ranging from 88.8⁰F to
97.8⁰F and Flow Temperature ranging
between 74.7⁰F and 80.3⁰F. The
Barometric Pressure and Relative
Humidity conditions at the time of testing
were 28.47” of Hg and 26% respectively.
The air flow was 8.81 CFM at first lift point
which was a reduction from the stock head
standard. At peak lift though, the air flow
was 28.25 CFM which was a 5.13%
increase in flow. The main aspect of the
modification however, was to increase the
swirl and flow velocity. The swirl recorded
at each lift point showed a steady 3-7%
increase. The swirl figures were 2460
RPM vs. 2330 RPM for modified vs. stock
head. The figure below illustrates the intake
flow table and graph. (Refer Appendix D).
Fig. 11. Intake Port Air Flow Table.
Fig. 12. Intake Port Air Flow Graph.
DYNAMIC TESTING REPORTS
STOCK
The stock cylinder head was tested
dynamically on the engine dynamometer
for performance evaluation. The tests
performed were a Sweep Test, a Step Test
for warm-up and a 2- Minute WOT Peak
Torque Test for performance evaluation.
The stock cylinder head had a Peak Torque
of 8.7 Ft_Lb at 2350 RPM and a Peak
Power of 4.2 HP at 3750 RPM. The graph
illustrates the Stock Head performance.
Fig. 13. Torque, Power vs. RPM Graph
MODIFIED
The modified cylinder head was tested on
the engine dynamometer. A similar
procedure of warm-up and peak torque tests
was performed on the modified cylinder
head. The cylinder head produced a Peak
Torque of 9.9 Ft_Lb at 2300 RPM and a
Peak Power of 5.1 HP at 2900 RPM. The
graph illustrates the performance analysis
of the Modified Head. (Refer Appendix E).
Fig. 14. Torque, Power vs. RPM Graph

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CONCLUSIONS
Thus, as a conclusion to the project report,
the cylinder head had a better performance
output and greater port velocity for air flow.
In addition to this, the air had better
swirling properties which were confirmed
by a Brake Specific Fuel Consumption
Value of 0.632 g/KW-Hr. Also, for a full
two minute run at WOT, the Fuel
Consumption value would be 0.086 gms.
Thus, the modifications performed have a
positive effects on the engine performance.
COMPLETE AUTHOR
INFORMATION
Aditya Sripathi Venkata, is currently a
graduate student pursuing his Master of
Sciences degree in Automotive
Engineering Technology at Minnesota
State University, Mankato. Having
completed his Bachelors of Technology in
Mechanical Engineering in 2014, his
passion towards the Automotive industry
has led him to work at Volkswagen Group
Sales India Pvt. Ltd. and Mercedes-Benz
(Mahavir Motors), India. The areas of
focus and expertise include Automotive
Powertrain and Drivetrain development.
Ch. Kiran Kumar Reddy, is currently a
State University, Mankato. He has
Mechanical Engineering in the year 2014.
G.V. Satya Prakash, is currently a
State University, Mankato. He has
Mechanical Engineering in the year 2015.
ACKNOWLEDGEMENTS
We would like to thank Dr. Bruce Jones
(Department Chair and Professor,
AMET Dept.) for his valuable teaching,
encouragement for our group and the
immense confidence he has imparted to us.
It is with his guidance and supervision that
we could make this research paper possible.
REFERENCES
[1] Briggs & Stratton Animal Engine
Technical Manual:
http://www.quartermidgets.org/docume
nts/Tech/Briggs/2015_Animal_Tech_Ma
nual.pdf .
[2] Briggs & Stratton Official Website:
http://www.briggsandstratton.com/us/en
[3] Engineering Fundamentals of the
Internal Combustion Engine (2nd
Edition):
Author: Willard W. Pulkrabek
[4] Cylinder Head Intake Flow
Analysis: http://papers.sae.org/2013-01-
1409/
Authors: Jawad, B. and Arslan, S.
Date: April 8, 2013.
[5] CAE-Based Port Development and
Flow Design for SI Engines:
http://papers.sae.org/2005-01-0243/ .
Authors: Adomeit, P., Hopp, M.,
Schmidt, A. and Lang. O.
Date: April 11, 2005.

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[6] A Study on Combine Effects between
Swirl and Tumble Flow of Intake Port
System in Cylinder
Head: http://papers.sae.org/2000-05-
0098/
Authors: Jeong-Eui Yun, Jae-Joon Lee
Date: June 12, 2006.
[7] Basics of Cylinder Head Air Flow
Science and Porting Techniques:
http://www.enginebuildermag.com/2005
/12/cylinder-head-design-and-
modification-getting-started/ .
Date: December 2005. Author: Ken
Weber. First Edition: April 15, 2015.
Updated: May 18, 2015. Author: Jerry
Mostek
[8] Step by Step Head Porting:
http://www.superchevy.com/how-
to/95518-small-block-cylinder-head-
porting/ . –
Date: May 1, 2002.
Author: Scott Crouse.
[9] How to port a cylinder head:
http://www.howrah.org/cylinder-
head.html .
[10] Cylinder Head Porting & Polishing:
http://www.speedstore.ca/head_porting.
html .
DEFINITIONS, ACRONYMS AND
ABBREVIATIONS
CFM – Cubic Feet per Minute
Cu.in – Cubic Inches
CC – Cubic Centimetres
HP – Horsepower
“Of Hg – Inches of Mercury
RPM – Revolutions Per Minute
C.A.D – Computer-Aided Design
C.A.E – Computer-Aided Engineering
A.M.E.T – Automotive and
Manufacturing Engineering Technology

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APPENDIX
APPENDIX A – STOCK CYLINDER HEAD GRAPHS AND TABLES
1. Stock Intake Port Flow Graph
2. Stock Intake Port Flow Table

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3. Stock Intake Port Flow Graph and Table
4. Stock Exhaust Port Flow Table

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5. Stock Exhaust Port Flow Graph

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6. Stock Exhaust Port Flow Graph and Table

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APPENDIX B – STOCK INTAKE PORT SIMULATION OUTPUTS
1. Geometry Mesh Bottom View
2. Geometry Mesh Isometric View

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3. Geometry Mesh Front View
4. Residuals Plot

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5. Scalar Flow Scene Velocity
6. Vector Flow Scene Velocity

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APPENDIX C – MODIFIED INTAKE PORT SIMULATION OUTPUTS
1. Geometry Mesh Bottom View
2. Geometry Mesh Isometric View

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3. Geometry Mesh Front View
4. Residuals Plot

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5. Scalar Flow Scene Velocity
6. Vector Flow Scene Velocity

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APPENDIX D – MODIFIED CYLINDER HEAD GRAPHS AND TABLES
1. Modified Intake Port Flow Graph
2. Modified Intake Port Flow Table

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3. Modified Intake Port Flow Graph and Table

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APPENDIX E – DYNAMIC ENGINE PERFORMANCE TESTING RESULTS
1. Stock Cylinder Head Performance Results
2. Modified Cylinder Head Performance Results

Computer-Aided Design and Development of a Cylinder Head

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