Coil Pack Testing

[vlad01]

oh those ones. yeah I have a number of them.

[The1]

Not sure what you have actually done with these tests. The voltage figures on the primary are higher than the secondary. Can you explain just what you did. There are other factors that might come into play such as coil proximity and insulation. Please let me know just what you did to come up with these figures.

Sorry i know normally primary and secondary are for the input and output, i have measured each post. Atm i am using a spark plug and lead between them. Secondary being the plug and lead post it's attached to.

[pman92]

I would definitely be opening up the gap until it only just jumps it and measuring the voltage then. Will probably be a approx 25-30mm gap and produce a secondary peak voltage of 30-35kV.
If both different coils are hooked up to the same plug and lead they will both produce the same secondary voltage.

[vlad01]

I would definitely be opening up the gap until it only just jumps it and measuring the voltage then. Will probably be a approx 25-30mm gap and produce a secondary peak voltage of 30-35kV.
If both different coils are hooked up to the same plug and lead they will both produce the same secondary voltage.

Correct! thats what i was trying to get at.

and just FYI the V6 coils typically jump gaps of aprox 80mm so around 80-100Kv. I would say thats because they are bi-polar coils.

[pman92]

and just FYI the V6 coils typically jump gaps of aprox 80mm so around 80-100Kv. I would say thats because they are bi-polar coils.

That makes sense. I was thinking of only checking one side at a time on a car. If the coils on a bench and your jumping post to post I would expect double the gap and kV.

I think the point we are trying to make is the coil will only output the voltage it needs to to jump the gap. Eg if it only takes 2kV to ionise the gap of the spark plug on the bench, the secondary will peak at 2kV, the gap will then ionise and current will start flowing, the secondary voltage will drop and stay stable until coil energy gets too low, spark then stops and the secondary voltage oscillates until remaining coil energy is dissipated.

If you have 2 coils, one in good condition capable of 35kV, one with a fault in the insulation which will cause spark to fail after 5kV. Both coils will perform exactly the same on the bench jumping a 2kV gap, you would never see any difference. But once in the car at idle where there is a 10kV demand, the good one will work perfect and the faulty one will misfire consistently as it's easier to jump the 5kV insulation fault than the 10kV spark plug and electricity always takes the easyiest route.

[vlad01]

even if you do one it will still be the full output as its a its really one coil with floating outputs to operate in bi-polar mode. There is no ground for the 2ndary. The way it works on the engine is the current flows into one plug, through the block into the other plug and then back to the coil.

[The1]

that makes perfect sense, perhaps widen the gap and use an aircompressor to bend the spark? Yes it easily jumps from one post to another. I think my testing might be mute then, i dont think even with a 20:1 attenuator i wont be able to measure anymore than 12,000v or so. I need 2 in a row lol

[vlad01]

Just make a spark gap testing rig. 2 electrodes in a clear tube with adjustable distance.

you can get fancy and have a pressurised one to simulate different densities of air, like at several atmospheres worth where voltage makes a difference on small gaps like those on a spark plug.

[vlad01]

If you can get Helium you can make sparks go over 1m lol. The noble gases have low ionization levels and Helium is the lowest, so sparks can travel vast distances.

[The1]

ill give it another run tonight, ill keep the dwell down to help and see how it goes with increased gap.