9 replies to this topic

[ReeceTaylor]

I've seen pictures of people's ignition coils covered in energy drink cabs like Monster and Rockstar
How do they do it, anybody know?

[willava182]

cut on one side of a can, slot it on, turn it so you cant see it, put the mounting bracket over it (I imagine)

[cal844]

Easy
Unplug/ unbolt the coil
Size up the length vs the can, cut one end off
Slide it over the coil
Refit the coil bracet etc

[robminibcy]

ye, cut top of (or bottom), loosen the coil clamp slide it over the back of the coil, retighten the clamp. if the can is a bit big then cut both ends of, cut straight down on e side then wrap it round the coil with the joint at the back out of sight. Simples

[ReeceTaylor]

Thanks for your replies guys! It's safe to have a can placed over it though, right?

[Dan]

It'll run a bit hotter than it's meant to, but not a lot. It can result in damage eventually as a result but it's basically OK if you aren't in a desert.

[robminibcy]

It'll run a bit hotter than it's meant to, but not a lot. It can result in damage eventually as a result but it's basically OK if you aren't in a desert.

surely it would make negligible difference as the can would conduct heat in the same way the metal casing would have?

[KernowCooper]

Only thing is working on those cars the ends are like razors and easy to  slice you open, I am no thermal scientist but i'd imagine the inner of the can reflects the heat and does not allow the case to radiate so easiely ??

[Dan]

Exactly! It's a tiny increase but it does seem to cause failures.

[tiger99]

I would be very surprised if the difference was at all significant, especially if you habitually drive the  car fast, because an inductive discharge ignition system doesn't fully recharge the coil at high revs, so the average current, and therefore heat dissipation falls as the revs rise. Shame on you if your Mini spends its day mostly idling, they are meant to be driven! The real danger is when the ignition is on, engine not running, if the engine stopped at an angle where the points are closed. That is the worst condition for coil heating, and something that, when driving a petrol-engined car, I scrupulously try to avoid.

 

But I perceive that there might be a market for a nice machined or cast, finned anodised ali coil housing, with provision for filling the tiny gap between coil and housing with transformer oil to boost thermal conductivity. People pay good money for things that are purely pose factor, while skimping on safety-critical parts like wheel bearings, and the marketeers know that, so why no coil cooler?

 

Oh, and if the ignition system manufacturers had not abandoned the once very successful capacitive discharge systems (why?), there would not be a thermal problem, because a CD system has no coil current at all except when the timing sensor fires the spark.

 

Roughly speaking (it depends on various factors which may be unknown) the failure rate of an electrical item doubles for every 7 deg to 10 deg C temperature rise. Now, I have not experienced a single proven coil failure in maybe 600k miles of driving petrol cars, so in the days when they were made properly by Joe Lucas, they did not fail very often. I really would not expect the effect of wrapping with a coke can to make any noticable difference to the reliability. If it does, it is because the coil design has been stretched to the limit in some respect, or inferior materials or constructional methods have been used. Should I be surprised? The problem likely arises due to, sometimes, manufacture in back street factories in unsavoury parts of the world, and in other cases, by pushing the performance envelope to get some imaginary benefit from an old-fashioned inductive discharge system (basically just a solid state amplifier to reduce loading on the points). Bring back capacitive discharge ignition, and there will be no need to tweak coil design beyond sensible limits to get a decent spark. Better, bring back plasma ignition, only do it with high frequency AC, not the DC that eroded the plug tips, last time around. In short, fix the system in a way that was once known, understood, and readily available (even Halfprds sold Sparkrite or Lumenition CD systems) and the coil thermal problems will go away, again.