Automotive Coilpack Coversion?

[LikeMike64]

I have an idea brewing and would like the collective wisdom of the group.

If this is covered in a previous post, I apologize, I missed it in my search of the forum.

I have noticed that some cars with distributor-less ignitions have coil-packs with two spark plug wires per coil. Seeing how much technology has advanced in the ~30 years since our bikes were made, these must have much higher output than the OEM ignitions on our bikes. A hotter spark can only help. (Queue the Tim Taylor "Mo Pow'r" grunts )

I was wondering if one could use a couple of those coil-packs with maybe an Dyna S electronic module or the like on a bike. I am also wondering how much more current these draw than the stock coils (in view of the limited alternator output on these old GW's and the current capability of the electronic ignitions that fit them).

Thanks.

[mooseheadm5]

The answer is very likely, yes. Current should not be a problem.

[donspicer1]

the ohms resistance of the existing coils, I think they are around 3 ohms. whatever you buy, make sure they ohm-out about the same.

[LikeMike64]

Looks like the primary resistance is an issue.
According to Randakk's tech tips, the GW coils have a primary resistance of 2 ohms.
The four automotive coil packs that looked promising that I have found so far are all in the 0.27 to 0.53 ohm range. That must be how they are getting the hotter spark, by significantly increasing the current through the primary windings. I suspect that quadrupling the current load would burn out an electronic ignition like the Dyna S. Any suggestions?

[donspicer1]

if the dyna would be affected, it's using a power transistor, which is predicated on switching most anything. seems like I've read here in other posts that the dyna system eliminates the ballast resistor, and obviously, the capacitor for the points. dyna makes a coil that is about .5 ohm, for their ignition systems, so, that in itself lends support for what you have in mind. If I were you, I'd call those guys. here's their phone number.

1.800.928.3962

I wanted to go junkyard trolling with oh-meter in hand this past weekend, for exactly the same thing as what you did - but the weather was bad, cold, raining. what donor car did you examine?

[taunusrainer]

My Dyna III can handle 3ohms per coil, they supply a ballast resistor to be piggypacked onto the stock ballast resistor. They say stock coils must not be used without any resistor, because they have less than three ohms and will become too hot. I don't know if the DynaIII blackbox could switch a higher current. I would use automotive coil packs (like ford edis coils) with the corresponding ballast resistor ONLY. If Ford doesn't use a ballast resistor, they surely limit the current somehow else, by the ignition blackbox.
I don't know nothing about Dyna S systems, but there are several guys here who have one.
CU
Ray

[FirstYearDeek]

The resistance of the primay coil has vey little effect on the spark output; the secondary coil actually provides the voltage as the field in the primary coil colapses.

The reason for a higher or lower impedance has more to do with the charging system than any thing else. (I mean the system that provides current to the coil, not the battery and stador.)

Very low resistance coils are common in electronic ignition systems, where current limiting is possible with solid-state IGBT's. The current inrush during the dwell (charge) of the primary coil would be too high for stock points. They would not last long!

-Deek

[puffy75]

Your bike is not going to put out any more voltage for any coil you put on it other than what it is designed to do. You can get maximun voltage by removing the ballast resistor. The voltage at the primary led will then be battery voltage. That battery voltage will then charge the primary side of the coil and produce what it is designed to. However your current coils (stock are capable of producing near 40,000 volts) your bike,( as most) uses only a portion of that voltage. If your bike needs more than that 40,000 volts there is usually something wrong. Your wing probably in it's worst running condition uses about 10,000 volts of that 40,000. The 30,000 volts left is called "Reserve Voltage". It is needed to compensate for things that happen inside the cyclinder. Ie; as the spark plug gap is burned away by continuos sparking, the gap increases. When the gap increases there is a need for more voltage to jump the larger gap.
The Dyna is a better negitave control switch (Prestolite even better) because it will not wear like points. It stays constant controlling the on and off switching of the primary side of the coil (through it's ground side)and charging the secondary side of the coil for a "timmed" spark. In the GL1000's case both plugs. The primary side and secondary side never come in contact with each other except in the case of failure.

[donspicer1]

we're havin' fun now!

[mooseheadm5]

I have not seen any modern EFI setups use any sort of ballast resistor. The EDIS or similar coil packs are designed to be used with power transistors, as deek pointed out. If you built your own box, you could switch any coil pack you wanted. I think you can use an MSD type setup (not cheap though.)

[FirstYearDeek]

Switching an ignition coil with a transistor seems simple enough; until you consider the considerable inductive kickback (sometimes called "coil ring") from the field collapsing.

Couple that with the difficult job of current limiting and some pretty insanely short charge times with single-coil, high-revving engines and you're very quickly outside the specifications of normal transistors. Not to mention all the additional circuitry needed to achieve the other necessary functions for handling a coil.

This is why there are transistors specifically for this purpose. They're called "IGBT's" and they perform all the functions for charging, current limiting and handling of coil ring.

I'm all about electronic ignitions, when there's an advantage to having them. I've yet to see a reasonable argument against the standard points/coils arrangement on the GL's... provided they're properly installed and maintained, there are fewer opportunities for failure, in my opinion.

-Deek

[mooseheadm5]

I have two big arguments for electronic ignition on a Goldwing. More power to the plugs if you can eliminate the ballast resistor. This means better combustion, which means more power, better fuel economy, easier starts, more stable idle, etc. The second is more precise ignition timing is possible. Because the way the 1000 points cam works, you must get the timing close to the correct spot, but you cannot get it exact (see Randaak's split timing technique.) IGBTs are cheap, and if you can build the circuit, effective. IIRC, someone on a Megasquirt board posted a way to gut a Dodge coil pack and add the IGBTs to the base so that you could switch those with regular transistors. I cannot for the life of me find that post, though.

[LikeMike64]

Don, I checked:
Neon and Talon (Identical)
Bonneville (two variations)
Rodeo

Still looking

I wonder if one could use the ignition control module that comes with these and use the Dyna as the control feed to it.

[mooseheadm5]

maaaaaaybe. Depends on a few things. I would bet that on that front, the Megasquirt people would be the ones to ask.

[FirstYearDeek]

Neon/Talon will be GM DIS systems. They require some pretty complicated signaling; something akin to a crank/cam position sensor.

Bonneville the same, but slightly simpler.

Your best bet for 1) easy triggering and 2) better spark is to find some coil-on-plug units that have IGBT's built-in. These will allow you to switch the coils without high-current components.

The Corvettes use these, as do some other GM models. They're common on the 5-Cylinder motor in the H3 and the Colorado.

These coils, coupled with an optical or Hall effect sensor in place of the points on your bike would make for a pretty solid ignition system.

-Deek

P.S. This could get fairly complicated, fairly quickly. Have you considered simply purchasing an aftermarket electronic ignition replacement system? A bike will run with bad compression and bad gas; bad spark = no run!