EMI / RFI in Context
Why Ignition Creates EMI
- Spark plug wires carry fast, high-voltage pulses (20–50 kV with rise times under 100 ns).
- Each lead acts like a small antenna, radiating broadband noise into the surrounding harness and electronics.
- This interference is strongest in the AM radio band (~0.5–2 MHz) but extends well into VHF (10s of MHz), overlapping with many sensors and communication systems.
Where EMI Shows Up
- Radios/Audio: Static, whining, or popping in AM/FM and CB/HAM radios.
- EFI Sensors: Noise on crank, cam, or MAP sensor signals can cause erratic timing and fueling corrections.
- Aftermarket Gauges: Wideband O₂ controllers, tachometers, and digital ignition controllers are especially sensitive to ignition noise.
- Data Logging / Racing Electronics: Knock sensors, telemetry, and CAN-bus systems are vulnerable to corrupted signals.
- Crosstalk Between Wires: Adjacent wires can capacitively couple energy — classic example is V8 #5/#7 crossfire (plug fires out of sequence).
How IndestructaWires Solve It
- Stage One Suppression Core: High resistance damps noise by dissipating it as heat — but reduces spark current.
- Stage One Low-Ohm Core: Strong spark but more EMI radiated.
- Shielded IndestructaWires: Copper braid contains the EMI at the source, routing it to ground. Spark energy is preserved, EMI is dumped harmlessly into the chassis.
- Measured Effectiveness: 20–60 dB attenuation (10×–1,000× less radiated noise).
Why Shielding is a Game-Changer
- Unlike suppression wires, Shielded IndestructaWires don’t trade spark for silence. You get the strong, sharp discharge of a low-ohm core, without the electronic chaos.
- Especially important in:
• EFI conversions on older engines.
• Race cars with data loggers, aftermarket ECUs, or radios.
• Off-road rigs running comms, GPS, and digital gauges.
In Plain English
Unshielded wires = little radio transmitters under your hood. Suppression wires fix that by choking spark energy. Shielded IndestructaWires fix it by capturing the noise and grounding it, so you keep all the spark and lose all the noise.