Coil-On-Plug for Aircooled Engines?

[armandodiaz]

Subscribing, I changed the plugs on my wife's Boxster, the other day, and thought of the same thing for my track car.

[DUK]

Coils installed and running.....

[DUK]

[armandodiaz]

Can you tell us what you used?

[DMadigan]

Originally Posted by HawgRyder

Double ended coils are in fact two coils in one...with the ground in the centre of the assembly.

Have to disagree on this. Some dual ended coils may be that way but I have used Accel 140403 dual tower coils on BSA/Triumph twins. The secondary is wired to the two towers and no connection to either of the primary terminals. The disadvantage of these is that one plug is firing "backward".

Perhaps someone could answer this, I am building my '73 2.8L twin plug engine and have a choice of two 6 coil packs or COP. I am making new valve covers anyway so if I go with COP I want to mount them directly to the cover(sorry, two pieces of aluminum bar with a few holes in them is not worth $160). Does anyone know which model Bosch or Accel COP are the right length for this? Thanks

[winders]

On my 3.6L race engine, I am using the WeaponX coil on plug setup with 4 WeaponX 3 channel ignitors. Oh, with a MoTec M130 ECU.

[Neil Harvey]

Ignition is one of my sore points when it comes to these air cooled engines. I believe there are two main reasons why Inductive Ignition came about. Inexpensive to produce and for emissions.

I believe the reason Porsche went for Inductive on the last air cooled models was to meet the emission requirements.

With these large hemi chambered engines, I would not use Inductive ignition if performance is your goal.

Inductive just does not generate the in cylinder temperature that a good CDI can. Remember the fuel mixture immediately around the spark plug is ignited by the plug and the majority of the compressed mixture is ignited by this earlier ignited fuel. The more energy dissipated into the chamber the higher the pressure produced to push against the piston.

Some say the longer Inductive spark produces higher cylinder pressure but it in fact is doesn't. The energy produced in a Inductive system is no where as large as a good CDI system and that initial "hit" against the piston is so very important. After this, the piston is retracting downwards and the volume is increasing and as this is happening, the pressure value in the cylinder decreases.

This is along standing issue with many. I not here to argue the merits of one over the other, except to say, we never use Inductive on any air cooled 2V Porsche engine. Many use this for good reasons I'm sure but often have no idea that the performance in their engine probably decreased some. Its easy to fit multiple coils and its cheap compared. Remember most modern engines fitted with Inductive COP coils, have 1/2 the chamber volume these air cooled have and use a flat top piston in comparison with a centralized plug. All very different.

[DMadigan]

I looked at the Weapon X coils. It appears they need some sort of clip to hold them in place, not a screw hole as provided on the Accel coils. No data on their web site on dimensions. From what I have read on ignition systems, having too high voltage/power in the spark can ionize the gas and cause misfire. Not a believer in the bigger is always better advertisements.
Do you have any data on inductive versus CDI? I have not found any information on cylinder temperature using inductive versus CDI. Obviously, twin plugs need less advance due to the shorter burn time.
This is a street car with fuel injection. The heads were originally T, now ported and rechambered to correct compression ratio with S cams.

[bleucamaro]

Not strictly "Coil-On-Plug", (and not 911) but distributorless stand alone EFI, This setup runs as wasted spark, but could easily be setup for dual plugs. Just another idea / option.