Ignition Wires 101, Part 1

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By now, most enthusiasts know the merits of using a "spiral core" ignition wire on high performance powerplants. Yes, they suppress radio noise (obviously important for the boom box bunch); however, suppression wires are just as important in many high performance applications. Case-in-point is a Pro Stock racecar, which obviously isn’t fitted with a high fidelity sound system. Here’s an application laden with sophisticated electronics. Things like high-ticket data acquisition equipment, intricate ignition systems, multiple-step rev limit boxes, and perhaps most important, sophisticated electronic fuel injection, are on board. All of this electronic wizardry can be affected by the same "RF" noise that drives the sound system in a street car crazy. And that’s not the end of it either!

According to the folks at MSD, “Spark plug wires have two main objectives; transfer the spark energy to the plugs and suppress the Electro Magnetic Interference (EMI) that the spark voltage projects. Too high of resistance decreases the spark energy, yet too low of resistance may generate too much EMI noise, which will interfere with the operation of other electronics on the vehicle. A good quality wire, proper routing and routine inspection are all important in getting the most performance out of your ignition system."

Given the above, it’s pretty clear that both racers and rodders can benefit from the exact same ignition wire components. When you take a look at a good example of this type of wire (MSD’s 8.5-mm Super Conductor), you'll see this is its construction from the inside out:

Ferro-Magnetic impregnated center core
Kevlar material in the core improves tensile strength
Helically wound copper alloy conductor
High dielectric insulator
Extra heavy glass braid
8.5 mm jacket protects against high heat and resists tears

So far so good, but how do these helically wound wires work? A big secret is the conductor found inside the wire. The helically wound conductor offers low resistance for maximum high voltage carrying capability. Before we go any further, let’s rewind a bit: Years ago, enthusiasts associated solid core wires with high performance. The trouble was that radio noise was considerable with solid core wires (you could pretty much mess up vehicle radio reception for any car close to you). That isn’t the case with helically wound wires. As pointed out above, MSD’s Super Conductor wire has a copper conductor is helically wound around a ferro-magnetic core. This helical or spiral winding creates a radio frequency (sometimes referred to as "RF" noise) "choke," ensuring that the noise cannot leave the wire. Additionally, the helically wound wires prevent a phenomenon known as "inductive crossfire." This is created when something like a pair of stranded solid core wires run parallel to each other. When one spark plug wire fires, it induces voltage into the parallel wire. In something like a conventional Chevrolet application, the firing order is 1-8-4-3-6-5-7-2. Cylinder #7 fires directly after cylinder #5, and both cylinders are situated side by side in the bank numbering system.

What does this means? Well, it's significant because as cylinder #5 fires, #7 is just starting the compression stroke. If #5 and #7 are running parallel or if they are tied together, when #5 fires it can (and often will) induce a certain amount of voltage into the #7 wire. With the fuel charge already in #7 (along with a sufficient amount of compression), it fires easily. Keeping this in mind, you can easily see that this very early (advanced) and unplanned timing can quickly result in major grief. Of course, there's more to these wires than simply offering a profound resistance to "inductive crossfire." The wires also provide exceptional heat and chemical resistance. When all of the assets are tallied, they can actually increase the performance of your car when compared to conventional solid core or carbon core wires.

There are other considerations too: Even the best wire sets are at the mercy of the ignition system. As spark plug gaps increase and ignition power becomes stronger, the chance of leakage increases. High powered ignition control boxes are the norm today and because of this, almost all wires are susceptible to voltage leakage and, of course, cross fire. That’s why additional “insulation” is a good thing. These sleeves generally consist of a thick, closely woven glass tube or sleeve that is covered with a high voltage-resistant, high temperature-resistant silicone material. What's the added wire protection worth? According to the folks at MSD, their Pro Heat Guard sleeve can resist temperatures of 1000 degrees F. As a result, it's a good idea to consider sleeves as an added line of protection for your ignition wires.

Given the benefits provided by spiral wound wire, it simply makes sense to use these pieces on your super rod. Unfortunately, there's quite a bit of technical difference between these new wires and the older solid core models, especially when it comes time to terminate the wire and to install ends. We’ll look at much of the process in the following photos, and conclude it next issue. You might be surprised at the technology available in ignition wires along with wire accessories.

Website: www.msdperformance.com

The MSD Super Conductor wire is available pre-terminated. This particular wire set is designed for use on a big block Chevy with a crab cap.

Here’s another good look at MSD’s Super Conductor wire. This wire set comes pre-cut; however, it is possible to strip it yourself. See the accompanying photos for details.

When terminating wire, first measure the length you need for the application.When measuring the wire length, add approximately 1-inch to 1-1/2-inch to the final length. This will compensate for the wire stripping action.

MSD supplies a unique cutting/crimping tool with the wire. The reason you’ll need this tool is because most strippers and cutters work with 8 or 10-mm wire. The Super Conductor wire is 8.5-mm in diameter. You can cut it with a conventional wire stripper or you can use the supplied tool. Simply slide the wire into the tool as shown. Add a razor blade or sharp X-ACTO knife and hold it flush to the strip guide. Rotate the wire 360 degrees. Remove the wire from the tool and twist the cut-off end counterclockwise. This will cut the wire cleanly without fraying the unique spiral core winding or the protective outer sheathing.

Pull the small portion of insulation away, and the actual internals of the wire will become visible. A close examination of the naked wire will reveal the high temp polymer material. Under this covering is the special helically wound core along with the glass rope. This form of wire is not only radio and television friendly - it doesn't interfere with sensitive on board computer equipment. Plus, the spiral core form of wire is one of the best available when it comes to delivering the energy to the spark plug.

MSD supplies a complete set of wire number markers with the set. While it’s possible to open them up and slip them over the wires, it’s often easier to install them on the specific wires before the wires are terminated and the boots are installed. Next issue, we’ll deal with the terminal ends. We’ll also look at several very cool accessory items.