C.5.a. To find the TDC Event Order :
1. Turn the engine to TDC #1.
2. Rotate the engine in its normal direction of rotation.
3. Record the order in which the cylinders have TDC’s. It does not matter that the TDC events are
mixed between compression and exhaust during this process.
C.5.b. TDC Tooth for DFU “2” needed for an Odd-Fire Engine:
1. Turn the engine to TDC #1.
2. Measure the crankshaft degrees between TDC #1 and the next TDC event for the engine.
3. Take this Degree Number (
DN
) and divide it by 6. If the result has a decimal, round UP to the
nearest Whole Number (
WN
).
4. Add WN to the number 11 to give you the necessary value for the
TDC Tooth for DFU
“2”
parameter.
5. Perform the following subtraction: DN – WN =
X
.
6. Enter
X
into the
Rotary Ignition Split
table for all RPM points.
C.5.c. Harley-Davidson Applications
The unique sound of the Harley-Davidson V-Twin is the result of an odd (uneven) firing pattern
between the two cylinders. To run this engine, select
2-cylinder Odd-Fire
for the engine setup. Since this
is a 45
o
V-Twin with one connecting rod lobe, the TDC events occur in the following fashion for one
complete engine cycle:
TDC A
– 45
o
–
TDC B
– 315
o
–
TDC A
– 45
o
–
TDC B
•
For the TDC Setup,
Set the DFU #1 Trigger Wheel TDC to the 11
th
tooth.
Set the DFU #2 Trigger Wheel TDC to the 18
th
tooth.
•
In the
Dual Plug Timing Split
, set the values to 3 degrees for all RPM’s.
•
Wire DFU #1 -
Coil A1
output to
pin A
of a 4-cylinder DFU. This will fire cylinder A’s spark
plug.
•
Wire DFU #2 -
Coil A2
output to
pin B
(not pin C!) of a 4-cylinder DFU. This will fire cylinder
B’s spark plug.
•
For Phase-Sequential Fuel Operation, wire both injectors to channel 1.
C.6. Rotary Engines
______________________________________________________________________________________
TECgt Manual Version 2.0
- Page 47 -
©2008 Electromotive, Inc.
For rotary engines, the coil firing occurs on both the leading and trailing spark plugs. Using the
Dual Plug Timing Split Table
, simply enter the desired split (in degrees) between the leading and trailing
spark plugs. For a 2-rotor engine, 4 single tower coils will be needed. References to DFU #1 in the
software will correspond to the 2 primary spark plug coils (coil outputs A1 and B1), and will fire the
leading spark
plugs
on rotors 1 and 2, respectively. References to DFU #2 in the software will correspond
to the 2 secondary spark plug coils (coil outputs A2 and B2), and will fire the
trailing spark plugs
on
rotors 1 and 2, respectively. Typically, rotaries work well with about 7-15 degrees of split between the
