High Performance Spark Plug Wires

Ever wonder why spark plug wires are so thick? If you cut open a spark plug wire from a car, you'll see several layers and just a thin little wire strand running down its center. Why all of that insulation over the wire?

Spark plug wires must deliver precise power on a precise timing schedule. Anything that interferes with either of those parameters lowers the engine's efficiency and lifespan.

To accomplish both tasks, plug wires are heavily shielded against interference from the engine and the outside world. The type of shielding will depend on the construction of the plug wire itself and the engine it's meant to operate with.

In racing with carbureted engines, for instance, mostly unshielded, highly conductive wires are used as the concern there is power, not economy, and non-electronic engines do not need interference protection.

On most vehicles, however, protection from both radio frequency interference (RFI) and electromagnetic interference (EMI) is important. So wires are heavily shielded.

The Two Aspects of High Performance Plug Wires

High performance spark plug wires have two general aspects that make them "performance." These are their shielding properties against RFI and EMI and their highly-conductive inner core for more efficient movement of the power from the distributor to the plugs.

Shielding is almost always consists of fiberglass or Kevlar over the core wire and subsequently layered with high-resistance latex or silicone sometimes then layered with a softer, rubber-like plastic coating. This solution works well for low cost suppression, but generally has a shorter lifespan as the power flowing through eventually degrades the inner coating.

Most performance plugs use low-resistance spiral wires in which higher quality wiring is wound around a central core, making it more conductive (less resistive) and thus better able to transmit power from the distro to the plugs. Coatings around these are usually the same as above, but also often includes a carbon coating of conductive properties directly onto the wires to improve power flow. The problem with these "performance" wires is that they are often short lived and do not conduct power efficiently for very long.

Probably Not Worth It

While racers and amateur hot rodders might tout the benefits of high performance spark wires, most mechanics understand that in modern engines, quality is better than quantity. The quality of the power (meaning it's unadulterated by interference) is more important than the amount of power that can flow.

High performance spark plug wires usually focus on flow and do little to improve on interference abatement. Because of this, quality-made wires that meet manufacturer's specifications are usually all that's needed for today's modern engine to run at peak.

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