1. Design Team # 3 Shell Eco Marathon (Super-mileage Car)
Members:
Hussain Abdellatif
Sohaib Syed Alam
Julius Mantolino
Adam Procter
Supervisor:
Dr. Alex Kalamkarov

2. Outline Background Scope Design Requirements The Design
Current Project Status
Future Considerations
Design Requirements Check
Budget
Acknowledgements 2

3. Background Americas Shell Eco-Marathon Competition
not to go fast but to use least amount of fuel
Houston, Texas – (March 29-April )
2009 Dalhousie Team - 12th Place (819mpg)
Core Super mileage Team with 4 volunteers
Cover
Steering
Driver 3

4. Design Requirements Ultimate Goal: Achieve ≥ 900 mpg
Qualify/Compete for Shell Eco Marathon:
Geometric Limitations
4 stroke IC Gasoline Engine
Increased Fuel Efficiency
Lighter Powertrain
Lighter Chassis
Lighter & More Efficient Wheels 4

5. The Design – Our Scope Engine Fuel Injection System Powertrain Chassis
Transmission
Bearings
Clutch
Chassis
Wheels 5

6. The Design -Challenge Rolling Resistance Aerodynamics
Reduction in weight
More efficient wheels
Aerodynamics
Reduction in frontal area 6

7. Engine Direct Fuel Consumption Options Considered: Old 35cc Honda
Old 50cc XF Yamaha
New 35cc Robin Subaru
Honda 35cc [1]
Robin Subaru 35cc [2]
50cc XF Yamaha 7

8. Engine Selected : 35cc Robin Subaru
- Selection
Parameter
35cc Honda[1]
35cc Subaru[2]
50cc Yamaha[3]
Weight [kg]
3.00
2.80
11.34
Displacement [cm3]
35.8
33.5 49
Max. Power RPM]
7000
7000
8000
Max. Torque RPM]
5500
5000
6500
Max. Power to Weight Ratio [HP/kg]
0.43
0.57
0.44
Past Experience
Underpowered
N/A
Overpowered
Engine Selected : 35cc Robin Subaru 8

9. Engine Modifications -Electric Starter One-way Needle Bearing
Reused electric motor from Yamaha
Gear reduction 9

10. Engine Modifications -Muffler Requirement: Max. Noise Level <90 dB
Stock Muffler:
Lower Efficiency
Glass Pack Muffler:
Perforated Design
Packing diffuses sound
Less restriction
Glass Pack Muffler [4] 10

11. Fuel Delivery System Possible fuel delivery methods:
Carbureted
Port Fuel Injection
Direct Injection
Direct Injection is not Viable:
Requires mechanical fuel pump (competition rules)
Complex 11

12. Selected: Port Fuel Injection
Fuel Delivery System
-Selection
Carburetor
Port Fuel Injection
Advantages
No cost
Time savings
Controlled amounts of fuel
Conversion kit can be readily purchased
Disadvantages
Low efficiency
No control on optimum fuel consumption
Cost (~$800)
Needs pressurized system
Calibration and fine tuning
Selected: Port Fuel Injection 12

13. -Electronic Fuel Injection
Fuel Delivery System
-Electronic Fuel Injection
Replace carburetor
Conversion kit purchased from Ecotron:
Key components:
Oxygen (O2) Sensor
Fuel Injector
Programmable Engine Control Unit (ECU)
Fuel Pressurization System
Throttle Body 13

14. -Electronic Fuel Injection
Fuel Delivery System
-Electronic Fuel Injection
Control parameters as required
Engine Control Unit (ECU)
Throttle Position
Inlet Air Pressure
Fuel Injector
Inlet Air Temp.
Exhaust Temp.
Crankshaft Position
Engine Kill Switch
Programmable Control Parameters
Sensors – Input
Controlled Output
Exhaust O2
Spark Timing 14

15. Fuel Delivery System
-Pressurization
Fuel Pressurization System [5] 15

16. Powertrain Transmits power from engine Require minimum power losses
Provide sufficient torque
Best Efficiency Point (BEP) ∼ 5000 RPM
Provided by bsfc curve
To be verified with testing
Calculate suitable gear ratio:
𝑉 𝑎𝑣𝑔 =15 𝑚𝑝ℎ=6.71 𝑚/𝑠
𝜔 𝑤ℎ𝑒𝑒𝑙,𝑎𝑣𝑔 =19.17 𝑟𝑎𝑑 𝑠 =183 𝑅𝑃𝑀
𝐺𝑅= ≅28 16

17. Transmission Type Selected : Direct Drive
Powertrain
- Transmission
Direct Drive
Variable Transmission
Advantages:
Simple design
Cheap
Lightweight
Vary the gear ratio to the wheel
Change torque at wheel
Disadvantages:
Can’t run at BEP
Start-up load
Expensive
Complicated and heavy
Requires gear shifting
Transmission Type Selected : Direct Drive 17

18. Powertrain Components: Gear Reduction Method Two Stages Bearing Clutch18

19. Primary Stage Selected : Planetary Gearbox
Powertrain
– 1st Stage
Roller Chain
Timing Belt
Planetary Gearbox
Advantages:
Easy to design
Cheap
Light weight
Compact Design
High reliability
Disadvantages:
Weight
Large sprockets
Space
Pulleys sizes
Cost (~$800)
Medium Weight
Primary Stage Selected : Planetary Gearbox 19

20. Powertrain - Overall Planetary Gearbox for 1st stage
Purchase Neugart PLE60-20 Planetary Gearbox from Wainbee Ltd.
94% efficient
20:1 gear ratio
Continuous torque 44 N.m.
Roller Chain and Sprockets
for 2nd stage 20

21. Powertrain - Overall Planetary Gearbox for 1st stage
Roller Chain and Sprockets for 2nd stage 21

22. Bearings Selected : Ceramic Ball Bearings
Powertrain
- Bearings
Ceramic (Si3N4) Ball Bearings [6]
Steel Bearings
Advantages:
Significantly reduced weight;
(0.5 x steel)
30% the friction of steel
Provides smoother operation
Cheap
Disadvantages:
Expensive (10 x price of steel)
Heavier
More friction
Requires lubrication
Bearings Selected : Ceramic Ball Bearings 22

23. Powertrain
-Clutch
Centrifugal [7]
Friction Plate [8] 23

24. Clutch Selected : Centrifugal Clutch
Powertrain
-Clutch Selection
Friction Plate Clutch
Centrifugal Clutch
Advantages:
Flexibility in engaging
Less power losses
Greater torque capacity
Light weight
Compact
Automatic engagement
Disadvantages:
Heavier
Space
Risk of stalling  
Power losses during slippage
Spares
Clutch Selected : Centrifugal Clutch 24

25. Powertrain
-Torque Calculations
Engine is not overloaded 25

26. 30% weight reduction per unit length
Chassis
-Selection
Design Requirement: Lighter chassis
Aluminum Alloy 6061-T6
Yield strength = 275 MPa
Weight estimate entire car (with driver) ~ 90kg
Withstand static load of 700N on roll bar
Past team
Selected
1’’ OD by 0.125” thick
Cross section area = 0.34 in2
1-1/4’’ OD by 0.065” thick
Cross section area = 0.24 in2
30% weight reduction per unit length 26

27. Chassis
– Rear Loading
Max. Stress: 55 MPa 27

28. Chassis
– Side Loading
Max. Stress: 75 MPa 28

29. Chassis
– Pull Loading
Max. Stress: 50 MPa 29

30. Chassis
– Push Loading
Max. Stress: 43.8 MPa 30

31. Wheels 3 wheels: 2 in front, 1 in back Front Wheel Design
Lighter
No Internal Ratchet
Back Wheel Design
Internal Ratchet
Heavier
Back vs Front Wheel Assembly [9] 31

32. Wheels 3 wheels: 2 in front, 1 in back Front Wheel Assembly: Lighter
Past team
Selected
Front Wheels:
Small (406 x 44c)
Back wheels:
Back Wheel Design
Front wheels:
Larger (700 x 25c)
Larger (650 x 25c)
Front Wheel Design
Front Wheel Assembly:
Lighter
Larger Rim Size:
Less Bearing Loss 32

33. Wheels Hubs & Spokes to be purchased
Incorporate Sprag Clutch in Back Wheel
Disc Brakes:
Reusing from past team
Consistent brake performance
Hubs & Spokes
to be purchased 33

34. Wheels Past: Selected: Michelin road tires Continental GatorSkin tires
Higher inflation pressure
150 psi vs. 60 psi
Lower rolling resistance
Flat and puncture resistant
Durable
Michelin Tires [10]
GatorSkin Tire [11] 34

35. Wheels 35

36. Project Status Purchased: Designed: Robin Subaru 33.5cc engine
Electronic Fuel Injection (EFI) kit
PLE60-20 Planetary Gearbox
Aluminum tubing for chassis
Designed:
Power Train Components
Electric Starter Assembly
Chassis Main Frame Body 36

37. Design Req. Check Achieved Already To Be Achieved:
Qualify/Compete for Shell Eco Marathon
Geometric Limitations
4 stroke IC Gasoline Engine
Lighter Powertrain (Centrifugal)
Lighter Chassis (30% reduction)
To Be Achieved:
Increased Fuel Efficiency - to be confirmed with dyno
Lighter & More Efficient Wheels
Achieve ≥ 900 mpg - TBD 37

38. Future Considerations
Assemble Power Train
Assemble Power Train, Steering & Cover onto Chassis
Purchase Wheels & Wheel Components
Obtain Engine Curves with Dyno:
Carburetor
Fuel Injection
Fine Tune ECU Programmable Parameters
Dyno Wheels 38

39. Budget Engine $425 Fuel Injection System $586
Drivetrain & Clutch (estimate) $2000
Chassis $500
Wheels $2500
Total (15% Contingency) ~ $7000 39

40. Acknowledgments We would like to thank: Dr. Julio Militzer
Dr. Alex Kalamkarov
Albert Murphy
Mark MacDonald
Angus MacPherson
Peter Jones
Allison Chua, Drew Moores, Ryan Louie & Dainis Nams 40

41. Acknowledgements - Sponsors
We Thank Our Sponsors 41

42. References
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] D~ /continental-ultra-gatorskin-700-x-28-wire-tire.jsp 42

43. Questions ? 43

44. Back Up Material Engine Specs Load Torque Assumptions Bearings
Bearing, Output Shaft FEMS
Starter Assembly FEM 44

45. Engine Specifications45

46. Torque Calculations (1)
𝑇 𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 = 𝑇 𝑟𝑜𝑙𝑙𝑖𝑛𝑔 + 𝑇 𝑑𝑟𝑎𝑔
𝑃 𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 = 𝑇 𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 𝑉 𝑟 𝑤
𝑇 𝑟𝑜𝑙𝑙𝑖𝑛𝑔 = 𝑟 𝑤 ( 𝐶 𝑟𝑟 𝑚𝑔)
𝑇 𝑑𝑟𝑎𝑔 = 𝑟 𝑤 (0.5 𝜌𝐶 𝐷 𝑉 2 𝐴)
𝐶 𝑟𝑟 = 𝑝 𝑉
𝑝−𝑡𝑖𝑟𝑒 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑖𝑛 𝑏𝑎𝑟𝑠
𝑉−𝑐𝑎𝑟 𝑣𝑒𝑙𝑜𝑐𝑡𝑖𝑦 𝑖𝑛 𝑘𝑝ℎ
𝐶 𝐷 =0.4 [ref] – common CD used in old 90’s cars
𝑚=150𝑘𝑔 - the max. allowed in competition
𝑟 𝑤 =0.35𝑚
𝐴= 𝑚 2 - frontal area of around (19inx28in)
𝜌−𝑎𝑖𝑟 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑘𝑔/ 𝑚 3
𝑝=130 𝑝𝑠𝑖=8.96 𝑏𝑎𝑟𝑠 46

47. Torque Calculations (2)47

48. Torque Calculations (3)
𝑇 𝑐 = 𝜔≤ 𝜔 𝑒 −𝑐𝑎𝑠𝑒 1 𝑇 𝑐,𝑚𝑎𝑥 𝜔> 𝜔 𝑒 , 𝑇 𝑒 > 𝑇 𝑐,𝑚𝑎𝑥 −𝑐𝑎𝑠𝑒 2 𝑇 𝑐,𝑚𝑎𝑥 𝜔> 𝜔 𝑒 , 𝑇 𝑒 < 𝑇 𝑙𝑜𝑎𝑑 −𝑐𝑎𝑠𝑒 3 𝑇 𝑒 𝜔> 𝜔 𝑒 , 𝑇 𝑒 < 𝑇 𝑐,𝑚𝑎𝑥 −𝑐𝑎𝑠𝑒 4
𝑇 𝑐 < 𝑇 𝑓,𝑚𝑎𝑥 −𝑐𝑎𝑠𝑒 5
𝑇 𝑐,𝑚𝑎𝑥 =𝑛 𝑟 𝑜 𝜇𝑚 𝑟 𝑠 𝜔 2 − 𝜔 𝑒 2
𝑇 𝑓,𝑚𝑎𝑥 =𝑛 𝑟 𝑜 𝜇 𝑝 𝑚𝑎𝑥 𝐴
𝑚 = g, 𝑛=2  
𝑟 𝑜 =38.6 𝑚𝑚
𝑟 𝑠 =24.9 𝑚𝑚, 𝑐=1 𝑚𝑚
𝜇=0.25, [ref]
𝑝 𝑚𝑎𝑥 =1030 𝑘𝑃𝑎 [ref]
𝐴= 𝑚 2
𝑇 𝑓,𝑚𝑎𝑥 =21 𝑁𝑚
Engagement speed
Slip
Period
Max. Clutch Torque
Clutch “Bites”
Clutch transmits engine torque 48

49. Bearings 49 Ceramic (Si3N4) Ball Bearings Steel Bearings
Advantages:
Significantly reduced weight; density of Si3N4 is 3.2 g/cm3 versus 7.8 g/cm3 of steel
Co-efficient of friction is 30% that of steel
Less lubrication required Can operate at higher speeds (20% to 40% higher)
Smoother operation because modulus of elasticity higher (stiffer) than steel; 320 GPa vs 200 GPa – less deformations leading to less vibrations
Cheap
Better impact loading handling
Disadvantages:
Expensive (10 times the cost of steel bearings)
Heavier
Higher co-efficient of friction
Need for lubrication
More vibrations and rocky operation
Ball Bearings Selected : Ceramic Ball Bearings 49

50. Power Train Stresses 50

51. Starter Mount Stresses51