Quote:
Originally Posted by dannobee
I'll ask again, what modern car(s) use CDI? In the last 10-15 years?
I'm not saying that everything used by major manufacturers is the "best," but they do have to meet emissions and reliability standards, along with performance standards, and are consistently judged by their consumers and competition. There must be reasons why they choose the ignition systems that they do.
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Modern engines use much less oil than engines from the ‘60’s and ‘70’s. They use fuel injectors that deliver precise amounts of fuel and are controlled to virtually eliminate fuel fouling. The same controller can drive a coil for each cylinder, tripling or even quadrupling the inductance of the systems.
Compare that to an aircooled, carbureted Porsche engine with a dude and a gas pedal controlling the start fueling, and oil consumption that is bad to horrible by modern standards. So you can see that a COP is really the ideal ignition for a modern engine. The mixture is meant to be easy to ignite, and there is normally no oil fouling, something that a CDI ignition excels at solving.
Keep in mind that it is the temperature of the spark that ignites the mixture. That temperature is produced by ionization energy from the ignition, and once you get to that temperature, more energy doesn’t do anything. The inductive ignition can keep the ignition temperature hotter for longer than CDI, but CDI can also provide multiple discharges in some conditions to narrow that benefit.
A problem with CDI on a modern engine is that the intensive refinement of shift behavior, traction, emissions, and fuel efficiency is produced in part by slewing the spark rapidly between operating points. You would have to have a CDI with multiple capacitors to get the slew rates that an inductive COP system can produce easily.