Coil over plug ignition on a TIII?

[Tony Hanna]

Just wondering if anybody had considered this? John and I were junkyarding yesterday and I noticed some sort of newer Chrysler product (don't remember what exactly) with individual coils for each cylinder. Now I know there wouldn't be much benefit with the way the ignition system on the TIII is setup as each coil would still be firing twice per cycle (waste spark) just like the coil pack. What I'm wondering though is if the individual coils would be ok with that? I don't know how they're designed, so I'm not too sure if they would have sufficient time between each discharge firing at twice the normal rate. This is assuming the individual coil setups don't fire twice per cycle too (I can't see why they would).

The wiring would be easy enough (one common hot for all 4 coils, and common grounds for 1&3 and 2&4. It probably wouldn't be hard to locate a weatherpack to fit the connector on the harness for the stock coilpack, so no cutting should be involved.

I need to look a little closer to see what would be involved in building a bracket to support the coils, but I bet something could be designed to attach to the bolt holes for the valley cover.

I'm just looking for some input on this as an idea. I may or may not end up trying it depending on how cheap I can get the coils from the junkyard and how motivated I get. I know it's pointless, but it would be neat for the WTF factor if nothing else...
Thanks,
Tony

[iTurbo]

The GM Quad4 engines used something like that. There were coils mounted on the underside of the valley cover (so spark plug wires).

[turbovanman²]

Not doable without a standalone system. The problem is the factory fires the coils in pairs, hence the waste spark system. You need the computer to fire the individual coils at the corrrect time. Also the dwell time etc is different than a coil pack so again, you would need a controller that can fire them individually.

The Quad 4 wasn't quite a true isolated system, it had the module mounted on the cover and also had 2 coils for a wastespark system.

[Tony Hanna]

Right Simon, I completely understand how a waste spark system works, I'm just wanting to know if the coil on plug setups would have enough time between discharges to work properly firing twice per cycle (waste spark) instead of once per cycle.

Maybe a better idea would be to run 4 individual coils from a distributer type system. Then each coil would only be doing 1/2 the work it was designed for (firing twice per cycle instead of four times). Finding 4 coils that are small enough to fit in the valley would be the fun part.
Thanks,
Tony

[turbovanman²]

Right Simon, I completely understand how a waste spark system works, I'm just wanting to know if the coil on plug setups would have enough time between discharges to work properly firing twice per cycle (waste spark) instead of once per cycle.

Maybe a better idea would be to run 4 individual coils from a distributer type system. Then each coil would only be doing 1/2 the work it was designed for (firing twice per cycle instead of four times). Finding 4 coils that are small enough to fit in the valley would be the fun part.
Thanks,
Tony

That wouldn't work either, the coils couldn't charge up fast enough and the dist wouldn't be accurate enough.

4 coils is easy, the Ford 4.6 or 5.4 would work well.

If you really want to go small, look at GM's LS series, they have 8 small coils mounted above the valve covers.

[Tony Hanna]

That wouldn't work either, the coils couldn't charge up fast enough and the dist wouldn't be accurate enough.

I wasn't talking about using a distributer for anything. Just the coil (4 of them) from a distributer setup. Think about it, each coil would only be firing twice per cycle instead of four times like it would on a distributer (or 6 times or 8 times depending on what engines the coils came from). It would give each coil considerably longer to charge between discharge events.

4 coils is easy, the Ford 4.6 or 5.4 would work well.

If you really want to go small, look at GM's LS series, they have 8 small coils mounted above the valve covers.

I've looked at some of the setups MSD makes for the Fords. Looks like a tiny little coil with a spark plug boot sticking out of it. Size wise something like that would be perfect, but again it would be discharging twice per cycle instead of once, so I don't know if it would have the time to recharge properly in between.

Another thing I haven't taken into consideration is the coil drivers in the SBEC. I wonder how forgiving they would be about running 2 coils per driver?
Thanks for the input guys. Keep it coming!

[turbovanman²]

I wasn't talking about using a distributer for anything. Just the coil (4 of them) from a distributer setup. Think about it, each coil would only be firing twice per cycle instead of four times like it would on a distributer (or 6 times or 8 times depending on what engines the coils came from). It would give each coil considerably longer to charge between discharge events.

Ahhhhhhhhh,

I've looked at some of the setups MSD makes for the Fords. Looks like a tiny little coil with a spark plug boot sticking out of it. Size wise something like that would be perfect, but again it would be discharging twice per cycle instead of once, so I don't know if it would have the time to recharge properly in between.

Another thing I haven't taken into consideration is the coil drivers in the SBEC. I wonder how forgiving they would be about running 2 coils per driver?
Thanks for the input guys. Keep it coming!

I doubt the little coils could take running 2 cylinders, would probably overheat and fail,

[Tony Hanna]

Well, I was planning on running 1 for each cylinder, but they'd still be firing twice (top of compression and top of exhaust) during each cycle due to there only being 2 coil drivers, so I guess the effect would be the same. Basically each coil would be firing for an engine turning twice the rpm's. I'd say you're right Simon. At worst it'd eventually burn the coils up. At best I'd probably loose a lot of voltage in the upper RPM's.

I think I'll can that idea and look into using 4 more robust coils. It's a pity though, I was looking forward to having an engine without plug wires.

[Tony Hanna]

Well, far be it for me to quit beating the horse before it's completely stopped twitching. I went ahead and e-mailed MSD tech support with the question. We'll see if they think their coil on plug coils would be up to the task.

[Tony Hanna]

Got an email back from MSD tech support.

Sir,

If it is a "waste Spark" system you would be better off retaining a
waste spark coil instead of running 4 individual coils (in parallel).
The reason is that the waste spark coil is designed to operate in this
mode and the single coils are not. Running the single coils in parallel
to make them fire in waste spark mode will drop energy by roughly 50%.

Thanks,

MSD tech

That answers that question.
I guess I'll look into using one of the more common (Dodge or Ford) aftermarket 4 tower coil packs then.

[turbovanman²]

Great info.