COP mod

[Drunkn Munky]

Don't the latest ignitech units provide control over the coils? Ie being able to supply each one with 12v and firing each one at the right time?

There's still no performance gain there but you do get a lot newer technology, big outlay though.

[magg]

Putting aside the idea that if it ain't broke why change it, the rise & fall times are a function of the ignition coil design and not related to the applied voltage. Less applied voltage however will result in less current flow through the coil primary winding and thus less induced secondary voltage at time of firing. I also have a reservations regarding how the two coils interact at the point of firing. These issues may be cause for problems at high rpm.

If I was inclined to what to try using this new technology, I would add individual driver electronics between the OEM ignition control unit and stick coil. Not a bit issue to do but at least the coils would be working as the manufacturer intended.

[Neosophist]

Less applied voltage however will result in less current flow through the coil primary winding and thus less induced secondary voltage at time of firing.

Maybe that speculation is worded slighty wrong from the other forum I pasted but it IS on the right track.



Here are the dwell times required to charge some popular coils to the same output at different voltages.

Since the dwell time required is a lot longer at 6v than at 12v I can only assume that the spark is inadquate, at prolonged high RPM perhaps this will result in plug fouling or incomplete combustion?

[magg]

Neo would be interested in the full article from which you have provided an extract.

Also have included a method of configuring stick coils, can provide more detail if anyone is interested, but again why change something that isn't broke.

[Neosophist]

Neo would be interested in the full article from which you have provided an extract.

It's from DTEC Australia on how to properly calibrate ignition dwell times.

http://www.dtec.net.au/Ignition%20Coil% ... ration.htm

I have quite a few websites bookmarked as I did this mod a few years ago to my ZXR400 but it never ran quite right, no real performance degradation but didnt feel quite as crisp.

This is when I found out about dwell times, 6 volt coils and racers having problems.

http://www.extraefi.co.uk/dwell.htm

This is useful too, about the megasquirt ECUS and how voltage will adjust dwell timings.

[magg]

Neo, interesting reading but neither article provides material that is supported by my text book on current flow in a inductor/resistor circuit . In particular the formula provided by extrefi appears to be mathematically flawed.

As for dtec, I would question the characteristics of the driver they used in their rise time tests. Most modern drivers, as they themselves admit, have current control circuitry to stop coil saturation and control dwell. And other drivers have functions for low battery voltage during starting. Perhaps they ventured into one of these control areas when they varied the supply voltage from 6 to 16 volts and thereby changed to current supply parameters to the test ignition coil. These control functions can mask the inherent rise and fall times of the ignition coil but not change them.

Back to the NC30 situation, I would not expect series connected stick coil (COP) to work very well if only because it is not how the manufactures designed them to work. The OEM ignition control unit may not be entirely happy either, as an example, the flyback voltage produced by series stick coils may be greater than that produced by the OEM coil and thus could be a reliability issue.

However for anyone wanted to experiment, a further refinement of the recommended circuit in my earlier post would to use the latest technology stick coils that come with an integrated driver transistor. Simply connect a pair to the output of the OEM ignition control unit and away you go, well almost. Anyone interested?

[Morespeedvicar]

Would cost a bit tho, the bosch driver transistors were about £12 a few years ago when i was thinking of building a piggyback unit like your think of. But really dont see if there'd be much gain in doing it.
Cheers
Ian

[Variablevalves suck]

@ magg,

Went through this way back when racers started fitting cops.
Bosch stated they run between 6V and 24V BUT give a chart showing different dwell times per voltage.
Im unclear on this but believe this affects ignition advance.
Some ZXR racers were getting hot starting problems.

I ran them on the Bandit road bike and they are ok, you will not feel any difference, only seems to be on high tuned bikes that problems occur.