4 cylinder Twin Spark wasted spark

[madk4speed]

Hello. I have bought a MS-II and I am working on it's assembly. It's for a twin spark Alfa 75. I have seen this:

http://www.msextra.com/doc/ms1extra/MS_ ... htm#2coils

but I am not quite sure how many watts and ohms the resistors needed should be! In the previous link I can not figure out if I have to use 330 or 660 ohm resistors! These 4 extra transistors are going to be the Bosch automotive ones. I intend to used 2 x DIS4 coil packs to run my engine on wasted spark. Any special advice for the dwell setting for this case? Any ideas? The sooner I get some help, the sooner I will continue working on this project. Thank you!

[wes kiser]

I am helping friend (early 80's spider, twin spark head, and he made an ITB setup with integral stacks for it) with a similar setup.

Bosch has nice 4-channel ignitors that make for a cleaner install than individual ignitors. The 660 ohm pull-ups should work just fine.

Dwell necessary will be determined by the coils you choose.

[madk4speed]

Can't I use the circuit in the link i posted(Driving two coils from the same spark output e.g. wasted spark coil on plug (COP)) to drive directly my coils? Why should I use external ignitors? How many watts should the 660 ohm resistors be? 1/4 watts? I am using pcb 3.0.

[jsmcortina]

Internal or external ignitors work. The advantage of the externals is they have larger heatsinking and keep ignition noise and current out of the Megasquirt.

For the 680R resistors, 1/4W is just fine.

James

[madk4speed]

So can I ran from each spark output directly 2 channels of an external ignitor? External ignitors should require much less current so why using 2 x BIP373 transistors on each spark output to run 2 channels of external ignitors? Ordinary I would ran from each spark output 2 x BIP373 Bosch transistors which then would run 2 coils (1 coil for each BIP373 transistor). I have done a lot of reading, but ignition seems to be the hardest part. Especially in my case whrere I have 2 spark plugs per cylinder. I am really confused on the best solution for the ignition.

[acab]

i have 4 ts coils 1 227 030 062 in my alfa romeo twinsspark engine and work it in wasted spark mode with Bosch 0 227 100 211 Module.

and i use 4ms dwell, and module little warm. and i have some misfires when i get full throttle and little boost 0.4

;(

any ideas? may be increase dwell to 5ms?