Hello I will help you with your question,
The Accel flamethrower brand is 40,000 volts at 12 volt input, the GM HEI coils will put out 100,000 volts plus at 12 volts input and if you raise the input voltage it will raise the output voltage. A controlling factor in the amount of spark produced is how fast the current flowing through the coil is stopped. No coil is made to have current flowing all the time so you have to flow the current for a short time to build the magnetic field in the coil and stop it quickly to collapse the field producing the spark.
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