Railgun

So I just searched through about 400 posts worth of ignition crap. Damn if there wasn't a load of reundant threads...that's the source of my big *** search button.

Anyway...I've been trying to get something as far as actual specs for the stock FD coils. While I'm at it, I might as well get the same for FC coils since a popular option is to replace the former with the latter in a lot of cases.

I'm running an AEM CDI box with stock coils. They've performed flawlessly until recently when I found a hole in one of the trailing housings. Needless to say it was arcing like mad. I replaced it with a new FD coil and it promptly starting to arc to one of the mounting screws, though it was a weak spark. I though this was peculiar so I removed that screw and noticed it had started to arc internally (it was night at the time). It seemed that I fried this guy pretty quick. Or perhaps it was defective. None the less, I'm getting it replaced.

Before this took place, I had called a couple of dealership service departments wondering if they had this info. They didn't, so I called Madza N.A. and they indicated that I can't talk to an engineer about this and that a dealer would. SO I ran this past Ray Crowe and he took it upon himself to call Mazda. They 1) didn't have the answer and 2) arrording to Ray, pretty much blew him off. Wonderful.

So the short of it is this:
1) What is the winding ratio of the stock FD and FC coils
2) What's the rated maximum voltage output of the FD and FC coils. I think Mazda HQ in Japan may be on call for this one.

I want to know if I'm killing this things or if they can take it.

I've cross posted this in the Far East section since I doin't think those guys venture out this far too often. Perhaps their being local to Mazda out there they may be able to contact someone who'd have an answer.

Speed of light

iTrader: (8)

I've heard the hype and so I've measured both the FC & FD leading coils' characteristics as they present themselves to the ignition amps:

FC coil: inductance = 3.5mh, Q = 3

FD coil: inductance = 4.1mh, Q = 5

This is not a huge difference, but what it suggests is that the FD coil has less internal resistance and perhaps more turns of a larger ga. primary wire, and/or more core (iron) volume. I do not know if this relationship holds true for the trailing coils, but it may.

I did not measure turns ratio, as voltage output is overhyped and of little consequence, esp. when using CDI. (IMO) High voltages often cause more problems than they solve--yours may be a case in point.

To me, it looks like the FD coil could be saturated deeper and produce more current in the spark; thus hotter / longer duration (at least on conventional types of ignition). If you're using a CDI of some sort, the spark characteristics are going to largely depend upon the amplifier and its output impedance. Try and get that info from a manufacturer! I'm afraid you'll have to extrapolate it from the recommended coils data.

In any event, I have been running a MSD 6A on an old and very used stock FD leading coil with very good results and no reliability problems.

Incidentally, it is not uncommon to see some leakage, but you shouldn't have too much. You may want to be sure that the firing voltage requirement is not too high. (i.e., wires and plugs are ok and contacts are properly seated in the coil towers and on the plugs.) I've also seen hairline cracks that were almost imperceptible during inspection leak a lot of spark and cause misfiring/crossfiring.

Electricity will take the path of least resistance AND a pulse--a spark with a fast rise time--will take the path of least inductance...