MECHANICAL ENGINEERING DEPARTMENT AT THE UNIVERISTY OF MAINE
Fuel Injector Flow Bench
Addition to Existing Dynamometer Cart
Michael Galli, Kalee Gurschick, Andrew Gwarjanski, Lucas Farrar, David Raymond, Jakob Low
2012
Contents
Concept ......................................................................................................................................................... 1
Fabrication .................................................................................................................................................... 2
Wiring ............................................................................................................................................................ 3
Theory ........................................................................................................................................................... 4
Testing Procedure ......................................................................................................................................... 5
Sample Data .................................................................................................................................................. 6
Parts List and Drawings ................................................................................................................................. 8
Concept
As the Mech Lab portion of the senior design class, the CSC 2012 Team designed and fabricated
a fuel injector flow bench. The flow bench will provide a rate of fuel sent to the engine by the injectors.
This value is critical in properly setting the engine controls. The rate is dependent on the pressure set by
the fuel pump and the injector pulse width. To convert the engine to run with higher contents of
ethanol, the pressure must be increased due to higher fuel density and lower energy produced per unit
volume. The injectors may not be able to perform correctly under pressures higher than stock. The
injector pulses open and close to send small amounts of fuel at a time to the engine. The pulse width
defines the time the injector is open and is a key input in the engine control unit.
The schematic of the experimental set up is depicted in Figure 1. The fuel tank, filter, pump, and
regulator are all mounted on the existing dynamometer cart. The line is then connected to a pressure
gage that can connect to the apparatus containing the fuel injectors. These injectors will sit directly
above the graduated cylinders used for measuring.
Figure 1: Concept Sketch of Fuel Injector Flow Bench
1
Fabrication
The graduated cylinders will be housed on a stainless steel base, shown in Figure 2 below. This
base will also hold the injectors during testing. Each piece is fabricated out of 16 gauge stainless steel. It
was cut using the sheer in AMC building. Pieces needing to be bent were also done using equipment in
the AMC building. A dimensional drawing for each piece can be found in Appendix C. There was an
existing bracket holding a fuel pump, and regulator on the cart. A similar piece was fabricated out 1”
square steel tubing, with our fuel pump and fuel regulator mounted to it. This piece is removable and is
attached with the existing hardware on the cart. This piece is shown in Figure 3. A new tank for mineral
spirits, the injector test fluid, was also attached to the cart. The tank is mounted with a bracket made of
1” square steel tubing shown in Figure 4.
Figure 2: Fuel Injector Housing
Figure 3: Fuel Pump and Regulator Mount
2
Figure 4: Mineral Spirits Fuel Cell
Wiring
There was already a switch providing power to the bench included on the control panel. We
needed to distribute this power to Microsquirt, the fuel injectors, and the fuel pump. Since an existing
fuel pump was removed and replaced, as described above, the existing wiring on the cart was used. The
fourth switch on the control panel powers the fuel pump. The fifth switch sends power to the
Microsquirt controller and to the injectors on the fuel rail. From Microsquirt, pins 9 and 10 each connect
to an individual fuel injector. These wires send a pulse signal to the injectors based on the test mode in
the Microsquirt program. To protect the circuit, fuses were added, as shown in the wiring diagram in
Figure 5 below. Ground wires were connected from the Microsquirt unit and the fuel pump to the frame
of the cart.
Figure 5: Wiring Diagram
3
Theory
The maximum volume of fuel sent to a properly working engine is based on the engine output, the
specific fuel consumption, and the duty cycle. The relationship is shown in the equation below.
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 = max 𝑒𝑛𝑔𝑖𝑛𝑒 𝑜𝑢𝑡𝑝𝑢𝑡 ∙ 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑓𝑢𝑒𝑙 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 ∙ max 𝑑𝑢𝑡𝑦 𝑐𝑦𝑐𝑙𝑒
Equation 1
The flow rate is in pounds per hour. The maximum engine output is 80 horsepower for the 2007 Yamaha
Phazer. The specific fuel consumption for this type of engine is 0.55 lb/hp/hr. The duty cycle is a percentage of how
long the injector is open. The injectors should not operate above 80%. Combining these values gives the maximum
flow rate shown below in Equation 2.
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 = 80 ℎ𝑝 (
.55𝑙𝑏
ℎ𝑝ℎ𝑟
) 0.80 = 35.2 𝑙𝑏/ℎ𝑟
Equation 2
The optimal flow rate for gasoline at stock conditions for the Yamaha Phazer is 35.2 lb/hr. Equation 1 can
be applied to any engine.
For high impedance injectors, the period is a constant 66ms. The open time is the set pulse width and the
close time varies to achieve the specified period. There for the trial time only a function the number of squirts as
shown below.
𝒕=
(𝑷)𝑵
Equation 3
𝟏𝟎𝟎𝟎𝒎𝒔
𝒔
Where:
𝑡
is trial time in seconds
𝑃
is the period (open time + close time), here 66ms
𝑁
is the set number is squirts
Using the time of the trial and density of the test fluid, the volume can be converted to a flow rate.
4
Testing Procedure
The injectors are pressed into the adaptors and the connectors are attached to the injectors. A graduated
cylinder is placed under each injector to catch the mineral spirits test fluid after it exits the injector. Mineral spirits
is added to the 1 gallon fuel cell. The empty graduated cylinders are placed on the scale and a weight is recorded.
The main power disconnect is switched to the “on” position and the ignition key is turned on. The fuel
pump is turned on by simply flipping the switch on the control panel labeled “fuel pump”. The red light above the
switch is on indicating there is power at the switch. The lines leading from the fuel cell to the injectors are now
pressurized. A computer with TunerStudio software is attached to the auxiliary hook-up on the Microsquirt wiring
harness. The program is opened using the computer. The Microsquirt switch on the control panel is flipped to the
on position. This sends power to the Microsquirt engine controller and also to the injectors themselves. The
gauges on TunerStudio are now interactive. The Tools menu is clicked and Injector Test Mode is selected. A new
window is opened. On the drop-down menu, “Test Mode” is selected and the desired values for pulse width, close
time, and number of squirts are set. On the bottom of the window the button labeled “Burn” is selected to save
these parameters. On the drop down menu, “Repeat Test” is selected in order to begin the test.
After the injectors have gone through the desired cycle and the Test Mode has stopped, the graduated
cylinders are removed and set on a level surface in order to get a volume reading. The graduated cylinders
containing the test fluid placed are placed on a scale to get a mass reading. This value is subtracted from the empty
cylinder weight and multiplied by the density of the test fluid to calculate a volume. The second volume reading is
compared to the initial reading directly from the cylinder. The cylinders are emptied into the fuel cell and placed
back under the injectors. A new pulse width is entered into the Injector Test Mode window and “Repeat Test” is
selected on the drop down menu to run a new test. The remaining trials are repeated in the same manner
described above until all desired pulse widths have been tested.
5
Sample Data
A test was done for the 2007 Yamaha Phazer fuel injectors. The value for pulse width ranged
from 5 ms to 50 ms in steps of 5 ms. The number squirts was set to 250. These are high impedance
injectors so the close time was calculated to ensure a constant period of 66 ms. The data from this trial
is shown below in Table 2. The values used for unit conversion are found in Table 1.
Table 1: Unit Conversion Values
Density of Mineral Spirits [10]
6.531
lb/gal
Weight Conversion
2.2046
lb/kg
Volume Conversion
0.0002642 gal/mL
Table 2: Trial Data
Pulse
Close
Width
Time
(ms)
(ms)
5
61
Trial
Time
(s)
16.5
Trial
Time
(hr)
0.00458
A
(mL)
6
B
(mL)
6
Sum
(mL)
12
Volume
(gal)
0.0032
Weight
(lb)
0.0207
Measured
Mass
(kg)
0.009
Measured
Weight
(kg)
0.0198
Average
Weight
(lb)
0.0203
Flow
rate
(lb/hr)
4.423
10
56
16.5
0.00458
13
13
26
0.0069
0.0449
0.019
0.0419
0.0434
9.464
15
51
16.5
0.00458
19.5
20
39.5
0.0104
0.0682
0.029
0.0639
0.0660
14.410
20
46
16.5
0.00458
26
26
52
0.0137
0.0897
0.039
0.0860
0.0879
19.168
25
41
16.5
0.00458
32
32
64
0.0169
0.1104
0.048
0.1058
0.1081
23.591
30
36
16.5
0.00458
39
39.5
78.5
0.0207
0.1355
0.06
0.1323
0.1339
29.207
35
31
16.5
0.00458
46
46
92
0.0243
0.1587
0.071
0.1565
0.1576
34.393
40
26
16.5
0.00458
52
52
104
0.0275
0.1795
0.081
0.1786
0.1790
39.057
6
2007 Yamaha Phazer Injector Flow Rate
45.0000
Flow Rate = 0.9703(Pulse Width)
40.0000
Flow Rate (lb/hr)
35.0000
30.0000
25.0000
Measured Data
20.0000
Target Pulse Width
15.0000
Linear (Measured Data)
10.0000
5.0000
0.0000
0
10
20
30
40
50
Pulse Width (ms)
Figure 6: Fuel Injector Flow Rate as a function of Pulse Width
The data was plotted and fitted with a linear curve. The equation of this line is used to determine the
maximum pulse width. This is shown below in Equation 5.
Equation 5
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 = 0.9703 ∙ 𝑃𝑢𝑙𝑠𝑒𝑤𝑖𝑑𝑡ℎ
𝑃𝑢𝑙𝑠𝑒𝑤𝑖𝑑𝑡ℎ =
35.2 𝑙𝑏/ℎ𝑟
→ 𝑷𝒖𝒍𝒔𝒆 𝒘𝒊𝒅𝒕𝒉 = 𝟑𝟔. 𝟐𝟕𝒎𝒔
𝑙𝑏/ℎ𝑟
0.9703 𝑚𝑠
The resulting maximum pulse width for the 2007 Yamaha Phazer fuel injectors is 36.27 milliseconds.
7
Parts List and Drawings
Part Number
555-100911
555-100021
361-804606
361-925106
555-100242
555-100333
555-100222
361-992908
361-300106
361-840106
023FBM2978
555-100322
JIF-31506
Description
Braided Steel Hose 6 AN
90o Female 6 AN to Hose Fitting
45o Female 6 AN to Hose Fitting
180° Female 6 AN to Hose Fitting
T-Fitting 6 AN Female Swivel on Branch
Flare Bulkhead Fitting 6 AN Straight
6 AN Female to 3/8” Male NPT
8 AN Female to 6 AN Male Reducer
8 AN Fitting Cap
Female 6 AN to Hose Fitting Straight
Male 6 AN to Hose Straight Adapter
90° Female 6 AN to Female Swivel Coupler
128-3039
Female 6 AN to Female 6 AN Adapter
Jiffy Tite 3000 Series 6 AN Quick Connect
Female
Male 6 AN to 10 mm Adapter
400-920
Fuel Pump Mounting Hardware
GSL414
Walbro Fuel Pump
555-15032
1728
1069-6AN
821-2010A
N/A
N/A
N/A
N/A
N/A
Fuel Filter
Edelbrock Fuel Pressure Regulator
Fuel Pressure Gauge 1/8” NPT
RCI Aluminum Fuel Cell
8 mm Rivet Nuts
Mineral Spirits
6061 Aluminum 1 in. hex stock
1 in. square stock
16 gauge stainless steel (3ft x 4ft)
8
Supplier
Jegs
Jegs/Summit Racing
Jegs
Jegs
Jegs
Jegs
Jegs
Jegs
Jegs
Jegs
Jegs
Jegs
Quantity
12 ft
10
1
1
1
2
2
2
1
2
3
2
Jegs
Summit Racing
1
1
Auto Performance
Engineering
Auto Performance
Engineering
Auto Performance
Engineering
Jegs
Performance Parts
Pegasus
Jegs
Fastenal
Central Storage
Lane Supply
Lane Supply
Lane Supply
2
1
1
1
1
1
1
25
1 Gal
1 ft
2 ft
1
9
10
11
12
13
14
15
16