Are M50 coils CDI or Kettering style ignition?

[Jon K]

Winfred? Bill? Anyone?

Are BMW M50 coils Kettering style or CDI style?

[Bill R.]

trigger the coil.




Winfred? Bill? Anyone?

Are BMW M50 coils Kettering style or CDI style?

[Bellicose Right Winger]

My understanding is that difference between CDI and Kettering is in the electronics that trigger the primary, I don't think there's much difference in the coil design. CDI's trigger the primary with a couple hundred volts for a very short duration. You might be able to optimize a coil for CDI, but there are (used to be, perhaps) a lot of cars running aftermarket CDI's on stock coils, including two I owned. M50 coils only have 12 volts on their primary, I wouldn't call it a CDI.

Paul Shovestul



......Are BMW M50 coils Kettering style or CDI style?

[Bill R.]

correct, a true cdi is triggered by a 400vdc pulse from a capacitor into the primary of the coil.I was lumping all electronic ignition into the cdi category The original kettering used breaker points to collapse the primary causing the spark. Cdi was electronically triggered like the motronics is but the motronics also uses a break or collapse across the primary. In that respect the motronic ignition is more like the kettering ignition without the electronic triggering.




My understanding is that difference between CDI and Kettering is in the electronics that trigger the primary, I don't think there's much difference in the coil design. CDI's trigger the primary with a couple hundred volts for a very short duration. You might be able to optimize a coil for CDI, but there are (used to be, perhaps) a lot of cars running aftermarket CDI's on stock coils, including two I owned. M50 coils only have 12 volts on their primary, I wouldn't call it a CDI.

Paul Shovestul