Quote:
Originally Posted by mysocal911
Bottom Line: The use of archaic CDI technology for OEM automotive ignition in the 21th century is non-existence.
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Really? What about motorcycles? They pretty much all still use CDI.
OEMs don't use CDI on mainstream cars because inductive is cheaper. That is (literally to the accountants) the bottom line. Another factor is that modern engines run lean mixtures which suits the longer burn of inductive. 911s do not.
In high revving, rich mixture and high cylinder pressure applications, CDI is favoured.
If you look at racing, high revving or high cylinder pressure is usually the driver, but in some cases plug fouling is the reason, see below:
Spark-plug
"Besides its tiny size, another interesting feature of the F1 plug is that there's no protruding hook on the bottom. That's because simply there is no room for one. A normal ground J shaped electrode doesn't have a chance of surviving in an F1 motor, It would get crushed by the piston or simply shaken loose by the intense vibration. When an F1 piston is at the top of its stroke, it just about touches the cylinder head. The combustion-chamber volume is mostly made up of the recessed parts in the piston tops that are there to provide room for the valves. Without that hook, the ground electrode is simply the bottom edge of the threads. This design is known as a surface-gap spark plug. Surface-gap spark plug is a spark plug designed to produce sparks along the isolator surface at the ignition end. This spark plug type is also classified as semi-superficial discharge type and superficial discharge type. This spark plug has a smaller heat exposed isolator, therefore, it gets dirty easily. To overcome dirt,
a capacitor discharge system is used which reaches rapidly the required voltage to produce the sparks. It is used in engines of high performance like the engines of Formula 1."