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Magnecor Ignition Wires
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Reduce crossfire, EMI, and RFI

Magnecor ignition wires w/ low-crossfire routing bracket

The ignition wires on the E30 M3 have always struck me as odd - the way they are crammed into that small, hard plastic loom does not seem like a very good idea. My friend Sean, who has spent many years building Trans Am cars, agrees with me. The first time I opened my hood to show him the "mighty" S14 he took one look at the ignition wires and scoffed that they were very prone to crossfire the way they were arranged. Thus it had always been my plan to arrange a more favorable routing of my ignition wires.

Factory S14 Ignition Wire Solution The basic problem with the factory S14 ignition wires is the way they are routed through the plastic loom. The wires have to bend through some very sharp 90 angles, and they are also caused to rub up against each other at various points along their path. If you want to see this for yourself, just open up the factory plastic loom and have a look. It's quite obvious.

It is fairly well known that after some time subjected to the extremely high vibrational environment of the S14 engine, the insulation surrounding the ignition wires can start to wear through. This allows crossfire to take place between the wires, which in turn causes the engine to misfire. The effect may be so subtle as to barely be noticed, but there will be a reduction in power nonetheless. The dust cover fitted over the distributor cap (not shown) makes things even worse. It causes the ignition wires to come together at a point almost as soon as they leave the cap.


BMW Motorsport Gr A Ignition Wire Solution It would appear from photos that BMW Motorsport might have been aware of this issue. For example, on the left we see a shot of an E30 M3 Gr A car with the hard plastic loom removed from the ignition wires. The wires are simply zip-tied together and left to flop around.

This still allows crossfire between the wires to occur, but at least the wires are not rubbing against each other or forced to bend through sharp 90 angles. In any case, these racecars probably had their ignition leads changed at very frequent intervals, so there was never a chance for damage to build up.

Part of my solution was to lose the hard plastic loom, but I also wanted to use "wire separators" to keep some nominal distance between the wires to reduce the likelihood of crossfire.

All that was needed was some type of bracket to keep everything in place...


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