hungryjoseph
06-28-2012, 12:03 PM
I just bought a set of 8 used coils with connects on ebay.
The factory RB25 ecu doesn't set the dwell time long enough for the Lsx coil to fully charge. For the Ls2 truck coils at 12 volts, the dwell time is 5.5 ms and increasing with respect to drop in voltage and decreasing with respect to increase in voltage. I found some chart that shows this relation for the LS2 truck coil. So the question I want to ask you guys is
1. When I look up dwell time adjustments, why does RPM make a difference (besides the extra voltage from a faster spinning alternator)? From what I've gathered, at 12V, the dwell time is 5.5 ms and the discharge time is 2 ms which means the maximum frequency is 133Hz which equates to 8000 RPM. BUT a spark in a cylinder occurs once every -TWO- RPM. Meaning at 8000 RPM, the spark is occurring at a frequency of 4000 times per minute. So theoretically (at 12 volts) you could spin the motor to 16,000 RPM before any adjustment needs to be made to the dwell time due to the motor frequency. Of course, at higher RPMs the coilpacks will see a higher voltage meaning the maximum theoretical RPM of the coilpacks is now even higher. Am I going wrong somewhere in my logic? I'm assuming there must be a reason people adjust for both RPM and voltage. I hope I was clear... lol.
2. Assuming everything I said above is right, I want to get an arduino board (Arduino - HomePage (http://www.arduino.cc/)) and code it so that when it sees a digital input, it will hold a digital output for -X- ms as a function of -Y- voltage. Meaning if the voltage is 12, it will hold a digital output (5V) for 5 ms to the coilpack, essentially creating a longer dwell time. These boards are cheap, 30$ to 100$, and can take multiple digital inputs and outputs, including analog. I also plan on using this for reading my pressures, temperatures, and RPM but that's for another thread. Any comments or suggestions for this idea?
thanks for any input.
The factory RB25 ecu doesn't set the dwell time long enough for the Lsx coil to fully charge. For the Ls2 truck coils at 12 volts, the dwell time is 5.5 ms and increasing with respect to drop in voltage and decreasing with respect to increase in voltage. I found some chart that shows this relation for the LS2 truck coil. So the question I want to ask you guys is
1. When I look up dwell time adjustments, why does RPM make a difference (besides the extra voltage from a faster spinning alternator)? From what I've gathered, at 12V, the dwell time is 5.5 ms and the discharge time is 2 ms which means the maximum frequency is 133Hz which equates to 8000 RPM. BUT a spark in a cylinder occurs once every -TWO- RPM. Meaning at 8000 RPM, the spark is occurring at a frequency of 4000 times per minute. So theoretically (at 12 volts) you could spin the motor to 16,000 RPM before any adjustment needs to be made to the dwell time due to the motor frequency. Of course, at higher RPMs the coilpacks will see a higher voltage meaning the maximum theoretical RPM of the coilpacks is now even higher. Am I going wrong somewhere in my logic? I'm assuming there must be a reason people adjust for both RPM and voltage. I hope I was clear... lol.
2. Assuming everything I said above is right, I want to get an arduino board (Arduino - HomePage (http://www.arduino.cc/)) and code it so that when it sees a digital input, it will hold a digital output for -X- ms as a function of -Y- voltage. Meaning if the voltage is 12, it will hold a digital output (5V) for 5 ms to the coilpack, essentially creating a longer dwell time. These boards are cheap, 30$ to 100$, and can take multiple digital inputs and outputs, including analog. I also plan on using this for reading my pressures, temperatures, and RPM but that's for another thread. Any comments or suggestions for this idea?
thanks for any input.