pcmhacking.net

using 30,000volts per 10mm rule

stock coils work out to be 120,000volt
Gorst / MSD Latest Gen coils 150,000volts
LSX 216,000volts

Check this post for pics of MSD coil versions, for the graph ive labeled them REV 1,2,3 from left to right in the photo for left to right in the graph
viewtopic.php?f=31&t=5136&start=160#p81035



Spark Gap Testing using 3ms Dwell Time 14volts, will update this graph as more coils are tested. Where x then number after coil name is shown it means more than 1 coil tested with same result.

Interesting.

Should do an MSD one as they are said to be as good as the L67 ones.

Can you repeat the test measuring spark gap distances before breakdown no longer occurs? Also maybe a test with the 2ndary loaded.

Nice! Scope on peak detect acq might help get the true max but secondary should be a fair bit more than the primary flyback voltage?

Primary current is also a good measurement to take. Can measure volt drop across a low value series power resistor on the ground side, assuming you dont have a differential probe for a high side measurement?

My intention was just to see if there was anything to grey, blue, yellow or Latest Rev MSD/Delphi coils. I have a known dodgy coil so have done various checking to try and find the best way to diagnose and measure a coils ability. By Dodgy i mean the car runs fine but misfires mid throttle mid range rpm, swapped out with known good coil and found the bad one.

So far ive found decreasing the dwell time till the spark is on the edge of no longer occurring provides a valuable reading, a good coil will have a stable voltage but a bad coil will oscillate all over the place or drop to sub 2000v, checking the waveform or voltage at any normal dwell times will show no problems. So far the grey and blue coils show the same voltage, i dont have any MSD/Delphi coils and yellow coils i dont have enough of. A good coil reads greater than 4000v using this test, one of the yellow ones i have reads 7000v.

What are these yellow coils?

accel I recon

Accel coils have a good rep.

I've used yellow ones before Yellow Bullet brand. Seemed good.

Nar the yellow bottom factory ones

Not sure what you have actually done with these tests. The voltage figures on the primary are higher than the secondary. Can you explain just what you did. There are other factors that might come into play such as coil proximity and insulation. Please let me know just what you did to come up with these figures.