Truth and myths about ignition wires




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Silicone ignition wires are superior


   Compared to modern thermoplastics designed over the past few years, silicone insulation is quite defective. Silicone belongs to the materials resistant to recycling. Mechanically is not as strong. That is why silicone wires are reinforced with glass fibre or nylon and usually covered with special casement for protection. This casement has another job to do. They additionally protect the wire set against rodent animals some of which find silicone tasty.

Classes A, B, C, D, E, F are quality classes


   False! According to ISO 3808 norm these are temperature resistance classes.
   A - is the lowest resistance,
   F - the highest. Quality and temperature resistance are two different things.
   Wires can be of highest quality and still be of C or D standard not E or F.

Silicone wires E or F class are the highest quality wires


    These are wires resistant to temperatures between - 40 oC and + 250 oC. Temperature resistance class cannot be mistaken for the quality of the wire. It is one of the less significant elements effecting the quality of wire. There are companies which advertise their wires as class G. It is only a marketing trick since class G does not exist in any norms.

The wire diameter has no effect on the quality of insulation or conduction


    Despite all the technological advance the laws of physics remain undefiled and a thicker layer of the same material is always more resistant to rupture than a thinner one. However one must keep in mind that insulatory properties of selected materials tend to be different so one must not reject smaller diameter wires beforehand.

    Properly made they may meet car manufacturers’ requirements. If it was not the case all would use 7 millimetre wires not 5 millimetre ones. Another thing is that thin wires are covered by protective casement against outer elements or the metal parts of the engine.

Gas engines require higher temperature resistance wires


    It certainly will not hurt but it will not help either. Gas burns at a higher temperature, however, the consequences are hardly felt outside the cylinder. The cylinder head cover near the plugs and the plugs are 50 oC hotter than in petrol engines yet for good quality wires it has little or no impact.

    However it is paramount for ignition wires not to cause a high drop of voltage. The reason for that is that the voltage on the electrodes must be significantly higher in gas engines than in petrol engines to produce spark. That is why carbon core wires with 7 kΩ/m of resistance are revived by many car manufacturers for gas engines (LPG or CNG)