1. –
EFI Design for the Junior 206 Engine
Cong Ding Duo Ding Tong Lin Shuhan Li Muzhi Zhu
2015-2016 MOTORSPORTS CAPSTONE
PROGRAM SPONSORS:
The team would like to acknowledge the financial
contributions of the following entities which made this
capstone experience possible:
MECHANICAL ENGINEERIG | STUDENT DESIGN PROJECT CAPSTONE
MAE.OSU.EDU | CAR.OSU.EDU
INTRODUCTION
This project was completed for OSU’s Supermileage
Team.
SAE Supermileage Competition Overview:
• A single-person vehicle powered by a single-cylinder,
spark ignited four-cycle engine provided by Briggs &
Stratton must achieve the highest combined miles
per gallon (MPG) over a set distance.
Electronic Fuel Injection (EFI):
The EFI system introduces electronics to the engine to
control the fuel injection into the combustion chamber
in hopes of increasing efficiency. This uses four main
system components:
• Fuel line system
• Sensors to detect useful outputs
• Wiring harness and engine control unit
• Software development
Capstone Project
• This project focuses on improving and optimizing
the fuel economy of the engine.
• Several designs have been proposed during
brainstorming process. Through cost and benefit
analysis and decision matrices, the team decided
on using EFI as the primary approach.
Fig. 1: Original Carburetor Engine
AIM
• The modified engine must achieve greater efficiency
than the unmodified engine (Fig. 1), which achieved
95 MPG in the 2015 competition.
• The engine must weigh below 20 kilograms.
• The required budget is $2,500
METHODS
SensorsandActuators
• Manifold Absolute Pressure (MAP) Sensor
• Inlet Air Temperature (IAT) Sensor
• Oxygen Sensor
• Hall Effect Sensor
• Capacitor Discharge Ignition (CDI)
Fuel Supply System Steps
• Designed and manufactured frame design
• Designed and installed fuel line
Testing procedure
Run the engine under 5 different throttle positions and 5
different RPM to simulate the engine performance with 25
sets of duties cycles.
Fig. 2: EFI Testing System Setup
RESULTS
• Torque reaches maximum value at about 1900 RPM.
The larger throttle position, the larger the engine
torque.
When the dyno is operating:
• ECU detects RPM data from hall effect sensor (Fig. 3)
and signals fuel pump to supply fuel to the injector
• ECU sends signals to CDI to activate ignition coil so
the spark plug fires the engine
• Throttle cable on throttle body controls input air
amount
Fig. 3: ECU Reading Diagram
ISSUES
• Coupler sleeve can not endure high torque. Also it
need be cool down after each operation.
• Utilize a more accurate apparatus for the fuel
measurement.
NEXT STEPS
• Add a generator to ensure the voltage supply remain
the same
• Change the pull starter to a electrical key starter.
Fig 4: Dyno Testing Setup
CONCLUSIONS
Our new system is fully functional and get improved in
several aspects (such as easy cold start, smooth idle
and running, faster throttle response, better fuel
efficiency and larger torque output) compare to the
original engine.