Beginner Question about Coils

[swong46]

Hi All,

I am gathering info on setting up the EFI for my motor and want to do something similar to:


It is a 4 cylinder but with twinsparks; I have read most of the threads about the twinspark and megasquirt but still have questions. A very basic question is do I need an external ignition module or amplifier or can I just use 4 of the COP's directly and have the remaining 4 piggybacked off of the original 4?

[Matt Cramer]

With B&G code, you'd need two EDIS modules to run the twin spark setup.

[swong46]

Can I use a single EDIS 8 instead of 2 EDIS 4?

[Matt Cramer]

Can I use a single EDIS 8 instead of 2 EDIS 4?

Only if you want half the coils to fire 90 degrees out of phase. (And I can't imagine any reason you would want that.)

[drholl]

Hey Matt,
Wouldn't this just be like a wasted spark. Only it would fire two plugs per cylinder (which would be for the same cylinder) and then in 360 degrees, fire the same 2 plugs in wasted spark mode?

In other words, Chevy firing order 1 8 4 3 6 5 7 2 -
just put:
1 & 6 in cylinder 1
8 & 5 in cylinder 2
4 & 7 in cylinder 3
3 & 2 in cylinder 4

Holl

[Matt Cramer]

EDIS 8 on a 4 cylinder? It would fire one output every 90 degrees. Not a desirable thing to do without a crossplane crank!

[drholl]

Put the twp opposing plugs in the same cylinder.

That way one plug would be the "Fire" plug and the other would be the "wasted spark" plug firing at the same time in the same cylinder. The two plugs fire at the same time in the same cylinder.

Holl

[drholl]

I bow to Matt's knowledge. He is absolutely right.
Don't listen to what I said above. I was wrong.

I was thinking the about the 8 plugs, but not thinking about "Where" on the 36 - 1 wheel it was performing the calculations. They are calculated every 90 degrees, just like Matt said.

Matt you have my sincerest apologies. I'll "think" before I go off half-cocked next time.

Holl