I would stick with aluminum and go with either 3 or 4.5mm thick. That way you can drill and tap the coil mounting hole.
grimreaper;1981962 said:I need to organize the scope images a bit before posting them. Way to many measurements that can be shown off one image. Makes it a cluster to see things.
The short story is this. Im almost certain the ignitor performs current sensing. A block of dwell time is provided that should allow the coil to fully charge, then current limiting takes place until the ignition event is triggered. The times listed below are from coil shorting (begin to charge) until current limiting takes place.
Stock 2.96-3.16ms
IS300: 3.16-3.2ms
Ford: 4ms+ (2 coils wired in series)
The ford coils do not reach the current limiting state at any rpm except idle. The ignitor appears to calculate a dwell window based off rpm, all calculated internally. This window has always been 3ms+ even as rpms increase. What you see on the scope is that the dwell window may 'shrink' a bit, but the coil has enough time to charge to current limiting state. Usually this window is 3.5ms-4ms as rpms increase.
At 6500rpm, the ignitor has 9.231ms per 360degrees of crank rotation. Coil for 1/6 fires every 9.231ms. Plenty of time and duty cycle left over to allow things to cool on the coil side. The stock coils need about 1-2ms to recover after a firing event, judged by the burn duration and oscillations. This varies a bit though.
The stock coils appear to be CDI coils with out a capacitor. Very low resistance. The Is300 coils are 0.6-0.5 ohms, stock 0.4-0.3ohms, ford 1.0-0.9ohms.
Installing a sense resistor to test the current ramp of each coil tonight. I believe the ford coils may be reaching a sufficient charge, although not the current the ignitor expects to see. Even if these are wired in parallel, the current limiting of the ignitor will prevent additional charge.
Once the ignitiors current limiting value is known, it should be easier to plan what will work best going forward.