Conductor & Spark Delivery (Oscilloscope View)
Ignition Coil Discharge Basics
- When the coil collapses, it releases stored energy as a high-voltage pulse.
- That pulse must jump the plug gap and sustain a current arc long enough to ignite the mixture.
- On an oscilloscope, this looks like:
- Rise spike: coil reaches breakdown voltage.
- Burn line: current flows across the gap.
- Tail-off: current decays until the coil is depleted.
High-Resistance Suppression Wire (~400–1,000 Ω/ft)
- Rise time: slower (coil has to “push” through more resistance).
- Burn line: lower current, stretched longer in duration.
- Effect: spark is weaker, but less noisy in terms of EMI.
- Why OEMs use it: cheap, quiet for radios, fine for stock compression.
Typical Performance Wire (~25–50 Ω/ft)
- Rise time: faster than suppression wire.
- Burn line: stronger, hotter spark kernel at the start.
- Effect: more consistent ignition under load, but still some EMI leakage.
Shielded IndestructaWires (~0.04 Ω/ft)
- Rise time: nearly instantaneous — coil dumps energy into the gap with almost no series resistance.
- Burn line: tall and strong — hot, dense spark kernel forms quickly.
- Tail-off: efficient discharge, less wasted energy as heat in the wire.
- Effect: the coil’s full energy makes it to the plug, while the shield prevents EMI from escaping.
- Translation: race-car spark quality without turning your engine bay into an RF antenna farm.
Voltage Handling
- Both Stage One and Shielded sets are built to withstand pulses above 50,000 V.
- That’s more headroom than most inductive ignitions will ever reach, but it guarantees margin under boost, high compression, or nitrous.
In Plain English
- High-resistance wires = weaker spark but quieter.
- Typical “performance” wires = hotter spark, but still radiate noise.
- Shielded IndestructaWires = hottest spark and no noise — the oscilloscope trace is as close to an ideal coil discharge as you’ll get in a plug wire.