Hmm, I think I see the issue then. The factory system has a capacitor for a couple hundred volts in the primary system, it's on the valve cover, I forget the nF/uF rating but that isolates the igbt from those voltages and helps pump the primary/secondary up, not in current (because it's a cap) but in voltage, I think it's technically called the condenser and that's literally the point of it. It captures breakdown voltage to increase primary (and subsequently secondary) potential, IE use all those nice mJ to jump a hot gap . To get 30-50kV you need the condenser to raise primary voltage into the hundreds momentarily to raise secondary to 30-50kV, so those flybacks make sense and I'd expect PR to make higher peak voltage as such. It all kinda fits in my head now.@V8bait Confirmations of my thoughts and I'm quite surprised we're not seeing more IGBT failures. The higher inductance of the PR coil is contributing to very high flyback voltages of over 430 V. This exceeds the IGBT's rated collector to emitter breakdown voltage of 390 V. In the stock N54 coil & B58 coil the IGBT is able to quickly clamp the flyback but with the PR coil that isn't the case. If you look very closely at the falling edge of the light blue (IGBT gate voltage) you can see a small step near the bottom of the edge on the PR coil, that appears to be leakage (which make sense since we're above the rated breakdown voltage).
View attachment 49012
Stock N54 Bosch flyback voltage: 344 V (within maximums)
View attachment 49014
Eldor B58 Flyback voltage: 336 V (within maximums)
View attachment 49013
I will be testing more coils tomorrow and hope to have those results added into this post early next week.
I don't think the condenser functions properly testing output through zenners since the voltage is low and load is increased, but should work fine in free air tests.
edit- on second thought that cap is just for driving primary voltage up and doesn't see the igbt.