Dwell time table – for coil-on-plug systems only, Dwell_time_table – Precision Turbo and Engine BigStuff3 GEN3 PRO SEFI System Hardware & BigComm Software User Manual
Page 55
BigStuff3 Pro SEFI System
Version 2.1 – February 2011
48
Input Shaft (Pulse/rev) – Assumes GEN3 system is equipped with the DAE option.
Input options – 1, 2, 4 or 31 pulses per rev. No input required unless the GEN3 system is
equipped with the DAE option. Call BigStuff3 for more details.
Turbo Shaft (Pulse/rev) - Assumes GEN3 system is equipped with the DAE option.
Input options – 1 pulse per rev – The turbo must have a tooth provisioned into the turbine shaft
for this to work.
19. Dwell Time Table – for coil-on-plug systems only
The dwell time affects the amount of primary current in the ignition coil. The longer the coil dwell the
more primary current available for a spark event. GM coils are current limited to a max of 7 Amps.
GM coils (approx 98mj of spark energy) reach their current limit in approximately 6 ms of dwell time.
BigStuff3 also offers optional “Hot” coils (103 mj of spark energy). BigStuff’s GEN3 ECU allows for
coil saturation at high RPM, where maximum spark energy is required, but also allows the coils to run
at lower dwell times (ms), at lower RPM, to avoid overheating the coils. Directional coil dwell times
to use are as follows:
LS1 coils with a 12V charging system.
From idle to approximately 4,000 RPM, use about 3.0 milliseconds near idle and no
more than about 4.0 milliseconds at approximately 4,000 RPM.
From approximately 4,100 - Max RPM, use no more than about 6 milliseconds of total
dwell time at max RPM.
LS1 coils with a 16V charging system.
From idle to approximately 4,000 RPM, use about 2.0 milliseconds near idle and no
more than about 3.0 milliseconds at approximately 4,000 RPM.
From approximately 4,100 - Max RPM, use no more than about 4.0 milliseconds of
total dwell time at max RPM.
The 1 x 16 table allows coil dwell-time to be set as a function of engine RPM.
Note: The RPM values, at the bottom of the dwell-time input table, are established when the Load vs.
RPM Axis table is configured.
An example of a default table, supplied with the system, is shown below.