Truth About Ignition Wire Conductors



Carbon conductors were used in original equipment ignition wires by most vehicle manufacturers, and still in the majority of stock replacement wires. This style of ignition wire is cheap to manufacture and generally provides good suppression for both RFI (radio frequency interference) and EMI (electromagnetic interference). Conductor usually consists of a substrate of fiberglass and/or Kevlar over which high-resistance conductive latex or silicone is coated, and functions by reducing spark current (by resistance) to provide suppression a job it does well while the conductor lasts. Vehicle manufacturers always treated ignition wires as service items to be replaced regularly, and limited life was never an issue. This type of conductor quickly fails (burns out) if a high-powered aftermarket ignition system is used.

EMI (electromagnetic interference)

EMI from spark plug wires can cause erroneous signals to be sent to engine management systems and other on-board electronic devices used on both racing and production vehicles in the same manner as RFI (radio frequency interference) can cause unwanted signals to be heard on a radio receiver. Engine running problems ranging from intermittent misses to a dramatic loss of power can result when engine management computers receive signals from sensors that have been altered by EMI emitted from spark plug wires. This problem is most noticeable on 1990's onward production vehicles used for commuting where virtually every function of the vehicle's drive train is managed by a computer. For many reasons, the effect of EMI on engine management computers is never predicable, and problems do become worse on aging production vehicles as sensors, connectors and wiring deteriorate and corrosion occurs. The problem is often exacerbated by replacing the original ignition system with a high-output system.


Solid metal (copper, tin-plated copper and/or stainless steel) conductor wires are still used in racing on carbureted engines, but can cause all sorts of running problems if used on vehicles with electronic ignition, fuel injection and engine management systems, particularly if vehicle is driven on the street — and damage to some original equipment and aftermarket electronic ignition and engine management systems can occur. Solid metal conductor wires cannot be suppressed to overcome EMI or RFI without the addition of current-reducing resistors at both ends of 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 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 both RFI and EMI suppression are 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 Japanese and European original equipment and replacement ignition wires do have spiral conductors that provide good suppression, and usually none of these wires are promoted as having low-resistance conductors. However, some have proven unsuitable for competition use when used with high-output ignition systems, as their conductors and pin-type terminations can be fragile and may not last as long as conventional conductor fold-over terminations.

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.

Claims of Horsepower Gain

Every brand of spiral conductor ignition wires will perform the function of conducting coil output to the spark plugs, but NONE, despite the claims made in advertisements and other promotional literature, will increase horsepower. Independent tests, performed when there was a frenzy of unsubstantiated claims of horsepower increases from spark plug wires, including a test performed by Circle Track Magazine (see May, 1996 issue) in the USA, show that NO "low-resistance" ignition wires for which a horsepower increase is claimed do in fact increase horsepower - the test also included comparisons with solid metal and carbon conductor ignition wires.

"CAPACITOR" EFFECT WIRES with grounded metal braiding over jacket

The most notable of exaggerated claims for ignition wires are made by Nology, a manufacturer of ignition wires promoted as "the only spark plug wires with built-in capacitor." Nology's "HotWires" consist of unsuppressed solid metal or spiral conductor ignition wires over which braided metal sleeves are partially fitted. The braided metal sleeves are grounded via straps formed from part of the braiding. Insulating covers are fitted over the braided metal sleeves. These wires are well constructed. For whatever reason, Nology specifies that non-resistor spark plugs need to be used with their "HotWires." In a demonstration, the use of resistor plugs with "HotWires" will nullify the visual effect of the brighter spark.

Ignition wires with grounded braided metal sleeves over the cable have come and gone all over the world for (at least) the last 40 years, and similar wires were used over 20 years ago by a few car makers to solve cross-firing problems on early fuel injected engines and RFI problems on fiberglass bodied cars only to find other problems were created. The Circle Track Magazine (USA, May, 1996 issue) test showed Nology "HotWires" produced no additional horsepower (the test actually showed a 10 horsepower decrease when compared to stock carbon conductor wires).

The perceived effect a brighter spark, conducted by an ignition wire, encased or partially encased in a braided metal sleeve (shield) grounded to the engine, jumping across a huge free-air gap (which bears no relationship to the spark needed to fire the variable air/fuel mixture under pressure in a combustion chamber) is continually being re-discovered and cleverly demonstrated by marketers who convince themselves there's monetary value in such a bright spark, and all sorts of wild, completely un-provable claims are made for this phenomena.

Like many in the past, Nology cleverly demonstrates a brighter free-air spark containing useless flash-over created by the crude "capacitor" (effect) of this style of wire. In reality, the bright spark has no more useful energy to fire a variable compressed air/fuel mixture than the clean spark you would see in a similar demonstration using any good carbon conductor wire. What is happening in such a demonstration is the coil output is being unnecessarily boosted to additionally supply spark energy that is induced (and wasted) into the grounded braided metal sleeve around the ignition wire's jacket. To test the validity of this statement, ask the Nology demonstrator to disconnect the ground strap and observe just how much energy is sparking to ground.

Claims by Nology of their "HotWires" creating sparks that are "300 times more powerful," reaching temperatures of "100,000 to 150,000 degrees F" (more than enough to melt spark plug electrodes), spark durations of "4 billionths of a second" (spark duration is controlled by the ignition system itself) and currents of "1,000 amperes" magically evolving in "capacitors" allegedly "built-in" to the ignition wires are as ridiculous as the data and the depiction of sparks in photographs used in advertising material and the price asked for these wires! Most stock ignition primaries are regulated to 6 amperes and the most powerful race ignition to no more than 40 amperes at 12,000 RPM.

It is common knowledge amongst automotive electrical engineers that it is unwise to use ignition wires fitted with grounded braided metal sleeves fitted over ignition cable jackets on an automobile engine. This type of ignition wires forces its cable jackets to become an unsuitable dielectric for a crude capacitor (effect) between the conductor and the braided metal sleeves. While the wires function normally when first fitted, the cable jackets soon break down as a dielectric, and progressively more spark energy is induced from the conductors (though the cable jackets) into the grounded metal sleeves, causing the ignition coil to unnecessarily output more energy to fire both the spark plug gaps and the additional energy lost via the braided metal sleeves. Often this situation leads to ignition coil and control unit overload failures. It should be noted that it is dangerous to use this style of wires if not grounded to the engine with grounding straps, as the outside of the braided cables will be alive with thousands of volts wanting to ground-out to anything (or anybody) nearby.

Unless you are prepared to accept poorly suppressed ignition wires that fail sooner than any other type of ignition wires and stretch your ignition system to the limit, and have an engine with no electronic management system and/or exhaust emission controls, it's best not to be influenced by the exaggerated claims, and some vested-interest journalists', resellers' and installers' perception an engine has more power after Nology wires are fitted. Often, after replacing deteriorated wires, any new ignition wires make an engine run better.


Never be fooled by any device that is fitted between the ignition coil and the distributor, and/or distributor and the spark plugs (sometimes in place of ignition wires) for which claims of increased power, multiple sparks, and better fuel economy are made. These devices have come and gone over the last 50 years, and usually consists of a sealed container in which the spark is forced to jump an additional gap or is partially induced to ground on its way to the spark plug gap. These devices can also be cleverly demonstrated to produce sparks the human eye perceives as being "more powerful." The only "increase" a gullible consumer can expect from these devices is an undesirable increase in load on their vehicle's ignition system.


All internal combustion engines rely on an ignition system and an engine that is required to produce more horsepower and needs to operate at higher-than-production-engine RPM needs a more powerful ignition system to achieve the extra horsepower and higher RPM.

Original (stock) equipment inductive ignition systems with distributors, and direct ignition systems that eliminate the distributor by controlling the ignition system with a computer, are designed to output spark energy moderately in excess of what is needed to fire spark plug gaps under normal operating conditions, and to control timing and spark duration to improve the engine's ability to control exhaust emissions, as well as ensuring the engine is not overstressed during the vehicle's warranty period.

Capacitor discharge ignitions (CDI) such as those from Accel, Crane, Holley, Jacobs, Mallory, MSD and others create sparks that are compressed (and intensified) into shorter duration and are designed to additionally produce the extra spark energy needed by race and modified street engines that will reach higher RPM than stock engines and use fuels more difficult to fire than pump gasoline (petrol). Most CDI ignitions incorporate multi-spark circuits to enable the engine to run smoother under 3,000 RPM.

A High-output inductive ignition system is probably more appropriate than a CDI ignition system for most late model production engines (modified or not) because this type of ignition provides the longer duration spark needed by these engines. Basic high-output inductive ignition systems are currently available in the aftermarket from at least Accel, Crane, Holley, MSD, and a menu driven direct ignition system is a available from Electromotive.

Often, on production vehicles used on the street, replacing a tired ignition coil with a higher-output ignition coil from Accel, Crane, Jacobs, Mallory, Moroso, MSD, Nology, etc, can improve ignition performance, particularly under load and at higher RPM.

Electrical devices, including SPARK PLUGS, use only the electrical energy necessary to perform the function for which such devices are designed. IGNITION WIRES are nothing other than conductors, and whereas an ignition wire's inefficient or failing conductor or insulating jacket (particularly a jacket inside grounded metal shielding) can reduce the flow of electricity to the spark plug, an ignition wire that allegedly generates an "increase" in spark energy will have no effect on the spark jumping across the spark plug gap, as the energy consumed at the spark plug gap won't be any more than what is needed to jump the gap (e.g. a 25 watt light bulb won't use any more energy or produce any more light if it's screwed into a socket wired to supply current to a 100,000 watt light bulb).

Although most new ignition wires will perform the function of conducting coil output to the spark plug, what is important to sophisticated race engine preparers and owners of production vehicles with exhaust emission controls is EMI suppression. All electronic devices can be effected by EMI emitted from ignition wires, and the problem is often exacerbated by installing a high-output ignition system. As production vehicles age, engine management sensors and wiring deteriorate and become more susceptible to EMI radiating from improperly suppressed ignition wires. To be truly effective, ignition wires need to be EMI suppressed for a reasonable time, while having the ability to maintain good conductance without overloading other ignition system components.

Engine tuners should also take into account that most stock engines and some hi-tech aftermarket engine management systems use resistance in ignition wires to sense additional information needed by the computer.


Since 1987, Magnecor has recognized that ignition wires capable of conducting the extreme energy output from ignitions available from Accel, Crane, Electromotive, Jacobs, Mallory, MSD and others, all of which are used on engines controlled by electronic engine management systems, need effective and permanent EMI suppression to avoid interference to vehicle electronics.

Magnecor Race Wires completely eliminate the need to resort to short-lived carbon conductor ignition wires to overcome the problems caused by EMI on race and performance vehicle electronics from improperly suppressed "low-resistance" spiral conductor ignition wires (with or without conductive coatings over conductor windings). Magnecor Race Wires are also extensively used on both stock and modified production vehicles which need to maintain exhaust emissions within the legal limit.

Unlike its competitors, some of whom have chosen to market "low-resistance" imitations of Magnecor Race Wires, Magnecor does not make any claim that their current KV85 Competition (8.5mm) and R-100 Racing (10mm) Race Wires have "low-resistance" conductors, nor do the conductors need "low-resistance" for any practical reason. Magnecor does not claim its Race Wires increase horsepower, and any horsepower gained by the use of Magnecor Race Wires results entirely from the ability of the wires to maintain full conductance and suppress EMI that previously robbed the engine of horsepower.

Magnecor Race Wires' 2.5mm Metallic Inductive Suppressed Conductors are designed to carry the full output from all race ignitions, and are exclusively manufactured in Magnecor's specialized facilities with precision machinery and equipment, and include microscopically close spiral windings wound over insulated ferromagnetic cores. No conductive coatings are used over the spiral windings. Magnecor Race Wires' conductors are jacketed entirely with the highest temperature aerospace grade silicone rubber to resist the extreme temperatures generated by race engines.

Since first introduced, progressive versions of Magnecor Race Wires have been consistently used by leading contenders all over the world, including those competing in SCCA, NASCAR, IMSA, NHRA and club events in the USA. To date, Magnecor USA has not sponsored any particular racer to promote the use of its ignition wires in competition events. All racers using Magnecor Race Wires do so to ensure their engines perform efficiently and without the risk of EMI from ignition wires ruining the enormous effort and expense necessary to prepare and tune engines for competition.

For over 30 years, Magnecor has also offered progressive versions of its 7mm and 8mm ELECTROSPORT ignition cables for carburetor, mechanical and early electronic fuel injected engines. These wires provide RFI suppression similar to the very best offered by Magnecor's competitors in the performance aftermarket, feature a far superior heat resistant jacket, and prices comparable to products sold through speed shops and mass-merchandisers.

This above document has been prepared by Magnecor to answer questions asked every day by both resellers and consumers. The information contained is also based, in part, on what has been conveyed to Magnecor's staff by racing and street engine tuners and vehicle owners in respect of their experiences with the majority of brand name ignition wires before and after they used Magnecor Wires.

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