I've seen posts (by efahl I think) that seem to indicate that a leaner AFR can be acheived by having a higher ignition output.
Which would be better, capacitive discharge or COP, or is there some other approach?
Which ignition allows leanest AFR?
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Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
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efahl
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Typically Kettering ignition delivers more energy to the charge than CD, but there are a couple of places where CDI shines. If you have a single coil on, say, a V8, then you run out of dwell time as the revs go up and fast-charging CD becomes a good solution. If you have enough coils to go around (1 coil per 1-2 cylinders), then fluxing time isn't a problem and you're better going with the inductive system.
On two-stroke, air-cooled motors, where you've got very rich mixtures containing oil, you can foul plugs quite easily, and the fast voltage build time that is characteristic of CDI allows it to spark through the oil where a standard inductive system builds the charge slower, allowing it to "leak" the voltage through the carbon/oil and thus never sparks.
Then there was Gar Willis's final research project before he passed away: BDI (BreakDown Ignition). This scheme puts much more energy into the initial fireball where it's needed; here's a 24 meg PDF with all the gory details. If someone ever gets this going, it would light some pretty big fires (but Gar reported EMI off his early test setups was just horrible, like being in the center of a lightning storm):
http://www.not2fast.com/ignition/pischi ... hinger.pdf
Bottom line today is that a well-designed inductive system delivers more energy at the right time than CDI, which is why it is so prevalent in new cars, esp the lean-burn ones.
Eric
On two-stroke, air-cooled motors, where you've got very rich mixtures containing oil, you can foul plugs quite easily, and the fast voltage build time that is characteristic of CDI allows it to spark through the oil where a standard inductive system builds the charge slower, allowing it to "leak" the voltage through the carbon/oil and thus never sparks.
Then there was Gar Willis's final research project before he passed away: BDI (BreakDown Ignition). This scheme puts much more energy into the initial fireball where it's needed; here's a 24 meg PDF with all the gory details. If someone ever gets this going, it would light some pretty big fires (but Gar reported EMI off his early test setups was just horrible, like being in the center of a lightning storm):
http://www.not2fast.com/ignition/pischi ... hinger.pdf
Bottom line today is that a well-designed inductive system delivers more energy at the right time than CDI, which is why it is so prevalent in new cars, esp the lean-burn ones.
Eric