I have been asked numerous times about using a cheaper lighting coil instead of a source coil for a stator’s ignition system. They may look similar, but there is a major difference.
That major difference is the wire size and number of wire turns/wraps. A lighting coil has bigger wire with less turns, while a source coil has smaller wire with many turns.
Why big wire and less turns for a lighting coil and smaller wire with many turns for a source coil?
A lighting coil needs to provide a low-resistance high-wattage output to run lights. The bigger gauge wire produces this while a lesser amount of turns is used because it only needs to provide about 12V. A source coil, on the other hand, is designed to put out far higher voltage and low current.
For the source coil the best design is a balance of two factors. Voltage Output vs Resistance/Heat. To maximize voltage you want as many turns as possible, because every turn cutting through the magnetic field gives a small boost in “electromotive force,” (EMF), which is similar to voltage. You want a fine wire to pack as many turns into the area where there is magnetic field, but making the wire thinner and longer increases resistance. At some point this will limit the current it can output from excessive resistance overheating the coil.
This balance of packing as many turns into the magnetic field as possible while keeping coil heat to an acceptable level is why after years of testing MSV Racing chose the coils we use for our “Faraday” High Power Stators, proudly made in the USA.