Well, I can see this is one of those topics that will never be agreed on. But, what some of you are saying is we have been living for decades with insufficient coils and NOBODY bothered to improve on one. And, the idea that MSD doesn't put more energy in a coil that those old points is one I can't agree with.
I don't think I saw anyone say that. Certainly not my intention. Mopar did make some better coils for electronic ignition under mopar performance. But you still ran a ballast, the values were just different. The sought-after race one was .25ohms. There is a chart floating around on A and B body only that would match the box, ballast and coil.
But why did you need an improved system in the late 70s when motor size, horsepower were going down. These were passenger cars. If you look at the GM mod guys do, your using a GM coil, not the mopar oil filled ones.
When the super stock cars moved to the prestolite box, it was the box, a low ohm ballast, and a special coil. Now the points only interrupted a very small current to fire the transistor, and they removed the condenser in the distributor and went with the very small point contact pad with heavy spring pressure to prevent point bounce and handle the higher 6400 to 6800 RPM of the hemi in 64/65.
So full circle, if a manufacture of the box today, states no ballast needed, they also specify a coil meant to work with the system, and they control current flow inside the box. Either with an internal resistor, or circuitry. But it still is an induction system. The coil is charged with current, and that takes time to reach the necessary charge to fire the plug. As RPM goes up less and less time to charge coil. If you significantly raise current than coil charges faster and at low rpm overcharges (saturates the coil), and coil temperature rises.
MSD is a totally different system. You are not charging the coil, you are charging Capacitors in the MSD box via a step-up voltage. Basically, charging the capacitors to 500V. When triggered the capacitor discharge through the coil which now acts as a step up transformer and creates the high voltage, low current discharge to the spark plug. Now you can multi spark because you are no longer relying on the coil to charge, your stored energy is in the MSD box.
From an MSD article, ""Up to this point we have mostly covered stock ignition systems which are classified as a inductive system because they rely on the coil to do the heavy work. These ignition systems do a decent job of creating combustion within an engine. However, if high horsepower is your goal then MSD suggests you should look at a capacitive discharge (CD) ignition. “The biggest advantage of a CD ignition system is its ability to produce full-power sparks through the engine’s entire RPM range with no fear of a weak spark at the top end,”
The CD ignition draws voltage supply from the battery and steps up the voltage to 500 volts and higher, it then stores the voltage in the ignition’s capacitor. Once it receives a trigger signal it will then slam the coil with this voltage and the outcome is a current that could reach the 30,000 to 45,000-volt range. The result is more heat in the cylinder which creates improved combustion."
Take the last sentence with a grain of salt. Engineering results are that 20-25KV is sufficient to fire a FOULED plug in testing. As long as the spark is sufficient to fire the plug and ignite the proper mixture, the extra volts does not mean more horse power, just more heat on the plug, and more wear and wasted engery.
Also not they say current, but describe voltage, so even the writer is miss using terms.
