The reason some "uprate" such items is to achieve higher ignition voltage, Splitfires for example produce a higher output than standard coils, according to independant test graph results I found online and also depicted on the companies website and packaging.
A coilpack is very similar to a power supply or a charger, be it a standalone device or a supply circuit integrated onto a motherboard, in the first instance as in a laptop and in the second instance as in a TV or satellite receiver. Power supply / transformer failure is a common fault in such equipment.
In the case of chargers as supplied for numerous devices, they fail less often as they are only required to provide low voltage / current supplies at trickle rates, so not so much heat is created and failures are therefore less frequent.
They all have one thing in common, a coil / transformer winding, and due to the fact that passing voltage / current through a length of coiled wire will always produce at least two usually unwanted byproducts they fail. The two byproduct culprits in this case are resistance and the resultant heat, the heat being the inevitable result of resistance.
This heat is enough to cause burns and should not be underestimated, it can cause extensive damage and even fires, ask Sony, they have over the last few years lost many many millions as a result of claims due to power supplies which exploded and or caught fire.
If you think how it's possible to pass voltage / current along a wire which is wound around itself without blowing everything up all should become clear.
It's only possible for a coil to function by insulating the wire before winding the coil, but to use the normal method of a rubber / plastic sleeve would make such devices huge and very heavy, totally impractical. So, the wire is coated in a thin layer of laquer (a sort of varnish) to provide the insulation required, but unfortunately this has a limited lifespan, or rather exposure time to the heat created in the coil. The laquer gradually hardens as it is continuously baked and then cooled, eventually cracking, as soon as that happens the winding shorts or arcs across from loop to loop internally. This destroys the properties of the winding, reducing the output voltage, which of course in the case of ignition circuits then affects our fuel burn.
The problem is then frequently exagerrated as the increasing heat caused by the breakdown of the insulation laquer and resultant arcing causes the outer covering / insulation to crack, allowing additional arcing to take place between the coil and any metal parts in the vicinity which are grounded, further weakening the required spark.
Relocation may lengthen the life in our case but will not remove the gradual breakdown of such devices, they will fail eventually regardless. Unfortunately that option also brings with it the age old problems of HT leads, an even worse option. So yes, of course you could deploy a remote coil system, but that's a backward step to Morris Minor days due to known weaknesses of HT leads. Yes you could fit special high end HT leads which would reduce those problems, but a set of those costs more than a set of new Splitfire coilpacks, and they will still fail more often than coilpacks!
They are just like many other parts in our vehicles, a service part requiring periodic replacement, and considering the job they do and how long they do it before failing they are phenomenal value for money. Just think how much a set of tyres cost and how often they need replacing, and we accept it, but in reality tyres are disgraceful value by comparison to coilpacks!
Aitch
