MSD and other CDI ignition half-truths

[Circlotron]

Do you know the coil part number?

[immortality]

I think it's 8207

[delcowizzid]

hec716 is meant to be a good coil HEC 715 (9 220 061 715) =92 mJ

[Circlotron]

Where did you get the 92mJ figure from?

Edit -> Found several references. This one is more reliable than most internet sources -> http://dtec.net.au/Ignition%20Coil%20En ... esting.htm

[Circlotron]

I think it's 8207

Yeah, that looks like it'd be alright.

[Holden202T]

very interesting read! how does your MSD6 differ from whats available today ie. 6AL etc ? I guess at the end of the day the coil is the majority of the oomph in the system.

most the speedway guys I see with MSD's use the vibration resistant MSD 6AL and blaster coils but that's about all I know of them ?

I'd be very interested to see the test results of an LS1 coil compared to the above info!!

[immortality]

I thought it was fairly well accepted that for low rpm stuff an inductive coil is best but the CDI systems shine at higher rpm where an inductive set up can't achieve full coil saturation?

With an inductive system there is not enough time to fully charge the coil if you start from zero every cycle. The flipside of that is that there is also not enough time to fully discharge the coil either. A good system finds the right ratio between charge time and discharge time for any rpm so the coil doesn't discharge too far, to make sure the coil just hits full charge at the moment a spark is required. Most, including 304 module, do not. Ideally it would also track accelleration to make sure the turn-on point is far enough ahead in time despite the shortening time between trigger pulses during accelleration.

What are your thoughts on these upgraded ignition modules?

http://www.ebay.com.au/itm/Holden-Commo ... 1e852e86b6

[antus]

I would also like to see ls1 coil tests. I think ls2 are overkill for most applications but would be interested in them too.

[Circlotron]

I'd be very interested to see the test results of an LS1 coil compared to the above info!!

This kind of coil -> http://www.knology.net/~rv7rotary/13_1_b.JPG
Same 1700 volt zener load string.
Internal coil driver limited at 8.3 amps.
Results:-

[Circlotron]

What are your thoughts on these upgraded ignition modules?

http://www.ebay.com.au/itm/Holden-Commo ... 1e852e86b6

I have never seen one but they would have to be better than the OEM ones. The OEM ones have a single-sided board and so they get cracked solder joints on the connector pins because of thermal cycling. Hopefully these boxes use double sided board. What would make a big difference is if the module looked after the dwell as a result of current sensing rather than the ECU just taking a guess. That sorta works okay at low revs but over 2000 rpm when the coil gets turned back on before the spark has gone out it's a whole new ball game. It gets tricky to do properly -> http://powerelectronics.com/power-manag ... ero-part-1