Vintage Newsletter - May 2010

The Technology Behind ipd Plug Wires

By: Rob Arnold - ipd research and development and special projects manager

Spark plug wires may not be as exciting as turbochargers, downpipes, or air intake systems but they are just as critical to proper engine operation and performance. Believe it or not spark plug wire technology has actually progressed, albeit slowly, over the years with little to no fan fare. So in an effort to give spark plug wires their 15 minutes of fame, let’s take a look back at how they’ve evolved over the years and what those changes have done.

In the early days of automotive engines, spark plug wires had to simply provide a conduit for the spark energy to reach the spark plug. With such a rudimentary job the wires themselves were quite rudimentary in their design; typically no more than a solid copper wire that connected the spark plug to its respective terminal on the distributor cap. It wasn’t long until insulating material was added to aid in combating misfires as the ignition components wore, but this basic design was around for a number of years and worked quite well for its time.

Fast forward to the early adoption of electronics to the automobile, namely radios. It became apparent that the high energy from the coil that transmitted through the solid plug wires created significant radio frequency interference. Manufacturers responded with a myriad of solutions, the most successful was limiting the spark energy through added resistance. This was done in a few ways, primarily through resistor type spark plugs and through a design change in plug wires. The change in plugs wires was from the previously used solid core wires to a carbon impregnated fiber wound wire surrounded by a rubber coating. This resulted in an increase of resistance in the plug wire which resulted in reduction in spark energy and aided in reducing the amount of RF that was transmitted to the radio. This became even more important as fuel injection systems came to market.

Fuel injection systems rely on a number of electrical signals fed to the ECU so that it can then inject the correct amount of fuel given the current needs of the engine. Many of the sensors used in fuel injection systems work on a lower signal range than the vehicles normal operating voltage of around 13 volts. Typically they will provide a 0-2 volt signal for the more critical signals like crank position or in some cases cam/distributor position. These signals are more prone to stray electrical energy and are therefore designed to use shielded ground wires that help capture and direct any stray RF in the engine bay. The ignition system is the primary cause of RF in the engine bay and as such, the design of spark plug wires must yet again be revisited. This time around, engineers found that if the carbon impregnated fiber was wound in a helix fashion it would make the wires act as pseudo inductors ‘holding’ the spark energy in a magnetic field rather than broadcast it like a radio antenna. This was helpful not just to the lower voltage signals found in the fuel injection system but also in the ABS systems that were becoming more and more prevalent.

Unfortunately, by and large, all the design changes to spark plug wires over the years haven’t contributed to increased spark energy but rather reduced it. This is undesirable from both a performance and efficiency standpoint, however the aftermarket has seen this and responded in kind. The sharp increase of available materials for plug wire construction has helped tremendously where we now see spiral wound wires with silicone jackets more common place and helping to bring back some of that lost performance and energy. ipd’s wires are no exception, with the same spiral wound technology and advanced material use, we are able to bring to market wire kits that offer original equipment fitment with greater energy transfer, all the while keeping unwanted stray RF energy at bay. Our 8mm silicone jacket helps reduce the likelihood of misfire meaning better transmission of spark energy to the spark plugs and increased performance and efficiency. If you’re looking for the best for your Volvo or maybe it’s simply tune up time and you want a higher performance wire kit, we’ve got the answer for you!

Spark Plug Wires by ipd!

Our custom spark plug wires are made with a high quality 8mm silicone jacket and feature a spiral wound core for maximum electrical efficiency. Each wire set is custom designed for each application covering over 40 years of Volvo models. Engineered to meet and surpass OEM quality. Each wire set includes spark plug and coil wires as well as dielectric grease used on the plug boots for easy removal at tune-up time.

NGK Spark Plugs

Starting with a single product in 1936, NGK has grown to become a world leader in spark plug and engine sensor technology. With manufacturing facilities in the USA since 1976, you can bet that the NGK plugs that we offer for your Volvo are of the best quality available. We use them in our own cars with proud success and reliability. What better endorsement can we offer?