There was a good discussion a while back on the VW engine group about electronic igniton. The newest DIS Compu Fire seems like the best choice if you are willing to use a distributor for it's timing. I am sure most of you are aware of this system, Great Plains sells it. If I understand it correctly, you place a round disk inside your distributor on the shaft where your rotor usually would sit(but no rotor or points required), it has 4 magnets placed 90 degrees from one another in it's surface, in other words one at each 12-3-6-and 9 oclock. The new anodized cap that comes with the system replaces your distributor cap and has the electronic pickup built into it, no points required. Wires come out of the lid to the coil pack. The coil pack has two coils in it, each seperate from the other. Each coil has two spark plug wires coming out of it. You place the two wires coming out of one of the coils on the two back cylinders spark plugs and the other coils two wires on the front two cylinders. If one coil fails then you have one coil left that will be firing the other two cylinders. Those two cylinders may get you to an airport, of course that would depend on your useable horsepower from two cyls and how much weight you are carrying. As long as you have an alternator still working or power in your battery, it is sorta like having a backup system. These coils produce 60,000 volts, so it is recommended that the spark plug gap be opened up some for a nice long spark which is very powerfull. I think a regular VW coil puts out about 30 to 35,000 volts, so as you can see the Compu Fire is powerfull. I will have to presume that the Compu Fire may use more battery than the normal VW coil system, but I do not know that I am just guessing. The coil pack mounts on the firewall so you will not have a tall distrubutor cap and wires on the engine. If you go to a VW repair facility you may be able to find the old style distributor that is very low profile as compared to the new 009 or whatever they are. The system senses the speed of the engine, so at no speed, as in starting it sets it'self close to TDC for starting and when at higher RPM as in cruising it will opperate at 30 degrees BTDC. As most of you know the normal VW distributor usually starts close to 7 degrees BTDC (before top dead center) and advances to only about 25 degrees BTDC. It is easy to see that the electronic ignition is supposed to be more efficient and maybe produces a little more horsepower. Electronics, I love them ! especially when they are working properly and they usually do. The backup electronic low profile distributor that Steve at Great Plains sells is permanently set at 30 degrees BTDC. That is why he says it is not for starting your engine, it is a backup for a single mag for example. It is said that an engine will start easiest at up to 3 degrees ATDC (after top dead center). So as I have learned you want close to TDC for Start and about 30 degrees BTDC for the most efficient cruise with these engines that we use for our aircraft. I have talked to a couple of people who use the Compu Fire Dis system only with no magneto and they firmly believe it is safe, best they have ever used and think they can make it to an airport if they were to loose one of the coils. The price is pretty good also, I think it is about $ 260.00. Not bad for a sorta dual system. Just my thoughts on Electronic ignition. Larry H.
