"LOW-RESISTANCE" SPIRAL WIRES

By far the most popular conductor used in ignition wires destined for race and performance street engines are spiral conductors (a.k.a. mag, pro, super, spiral, monel, heli, energy, ferro, twin core etc.). Spiral conductors are constructed by winding fine wire around a core. Almost all manufacturers use constructions which reduce production costs in an endeavor to offer ignition component marketers and mass-merchandisers cheaper prices than those of their competitors.

In the USA in particular, most marketers of performance parts selling their products through mass-merchandisers and speed shops include a variety of very effective high-output ignition systems together with a branded not-so-effective ignition wire line using a spiral conductor. Most perpetually try to out-do their competitors by offering spiral conductor ignition wires with the lowest electrical resistance. Some publish results which show their wires are superior to a competitor's wires which use identical cable (on which another brand name is printed). The published "low" resistance (per foot) is measured with a test ohmmeter's 1 volt direct current (DC) passing through the entire length of the fine wire used for the spiral conductor.

"Low-resistance" conductors are an easy sell, as most people associate all ignition wire conductors with original equipment and replacement ignition wire carbon conductors (which progressively fail as a result of microscopic carbon granules burning away and thus reducing the spark energy to the spark plugs) and with solid wire zero-resistance conductors that were used by racers with no need for suppression. Consumers are easily led into believing that if a spiral conductor's resistance is almost zero, its performance must be similar to that of a solid metal conductor all race cars once used. HOWEVER, NOTHING IS FURTHER FROM THE TRUTH!

What is not generally understood (or is ignored) is that as a result of the laws of electricity, the potential 45,000 plus volts (with alternating current characteristics) from the ignition coil (a pulse type transformer) does not flow through the entire the length of fine wire used for a spiral conductor like the 1 volt DC voltage from a test ohmmeter, but flows in a magnetic field surrounding the outermost surface of the spiral windings (skin effect). The same skin effect applies equally to the same pulsating flow of current passing through carbon and solid metal conductors.

A spiral conductor with a low electrical resistance measured by an ohmmeter indicates, in reality, nothing other than less of the expensive fine wire is used for the conductor windings — a construction which cannot achieve a clean and efficient current flow through the magnetic field surrounding the windings, resulting in poor suppression for RFI and EMI.

Of course, ignition wire manufacturers save a considerable amount in manufacturing costs by using less fine wire, less exotic winding machinery and less expertise to make low-resistance spiral conductors. As an incentive, they find a lucrative market amongst performance parts marketers who advertise their branded ignition wires as having "low-resistance" conductors, despite the fact that such "low-resistance" contributes nothing to make spiral ignition wires perform better, and RFI and EMI suppression is compromised.

In recent years, most ignition wire manufacturers, to temporarily improve their spiral conductor's suppression, have resorted to coating excessively spaced spiral windings, most of which are crudely wound around strands of fiberglass or Kevlar, with a heavy layer of high-resistance carbon impregnated conductive latex or silicone compound. This type of construction hides the conductive coating's high resistance when the overall conductor is measured with a test ohmmeter, which only measures the lower resistance of the sparse spirally wound wire (the path of least resistance) under the conductive coating and ignores the high resistance of the outermost conductive coating in which the spark energy actually travels. The conductive coating is rarely shown or mentioned in advertisement illustrations.

The suppression achieved by this practice of coating the windings is only temporary, as the spark current is forced to travel through the outermost high-resistance conductive coating in the same manner the spark current travels through the outermost high-resistance conductive coating of a carbon conductor used in most original equipment and stock replacement wires.

In effect, (when new) a coated "low-resistance" spiral conductor's true performance is identical to that of a high-resistance carbon conductor.

Unfortunately, and particularly with the use of high-output ignitions, the outermost high-resistance conductive coating over spiral windings acting as the conductor will fail from burn out in the same manner as carbon conductors, and although in most cases, the spiral conductor will not cease to conduct like a high-resistance carbon conductor, any RFI or EMI suppression will be lost as a consequence of the coating burning out. The worst interference will come from the so-called "super conductors" that are wound with copper (alloy) wire.

However, despite the shortcomings of "low-resistance" spiral conductor ignition wires, these wires work satisfactorily on older production vehicles and race vehicles that do not rely on electronic engine management systems, or use on-board electronics effected by EMI — although with the lowest-resistance conductor wires, don't expect much RFI suppression on the AM band in poor reception areas.

Some European and Japanese original equipment and replacement ignition wires including Bougicord and NGK do have spiral conductors that provide good suppression — usually none of these wires are promoted as having low-resistance conductors — however, none are ideal for competition use, as their conductors and pin-type terminations are fragile and are known to rarely last as long as good carbon conductor ignition wires.

To be effective in carrying the full output from the ignition system and suppressing RFI and EMI in particular, spiral conductors need windings that are microscopically close to one another and precisely spaced and free from conductive coatings. To be more effective, the windings need to be wound over a core of magnetic material — a method too costly for wires sold through mass-merchandisers and most speed shops who purchase only the cheapest (to them) and most heavily promoted products.