Ignition timing in rotary - what coil to which rotor

Discussion and support for MoTeC's previous generation of entry level ECUs

Ignition timing in rotary - what coil to which rotor

Postby Jfunesa on Tue Jun 20, 2023 8:45 pm

Hi!

I am testing the ignition circuit for a rotary engine (13BT DEI, for an RX-7 1989). The circuit has 3 coils: one Double Ended Wasted Spark coil, having the two leading spark plugs connected to it, and two coils for the trailing spark plugs (so one spark plug per coil). My engine has 2 rotors, they are shifted one from the other, so the trailing should occur at different phases for both rotors. The leading spark plugs will fire at the same time since they are connected to the same Double Ended Wasted Spark coil.
I connected my Sync sensor to an oscilloscope, and also the signal sent to the coils (one at a time). I get signals that make sense: indeed both trailing coils get one pulse per rotation of the eccentric shaft, and the leading double ended coil gets 2 pulses per rotation of the eccentric shaft, since one of the pulses is 'wasted'.
My question is therefore, how can I know what trailing spark plug should I connect to which rotor of my engine? I am not sure how I could check this.

Thanks!
Attachments
Trailing(3).PNG
Trailing(3).PNG (39.9 KiB) Viewed 22174 times
Trailing(1).PNG
Trailing(1).PNG (38.28 KiB) Viewed 22174 times
DoubleLeading(2).PNG
DoubleLeading(2).PNG (40.33 KiB) Viewed 22174 times
Jfunesa
 
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