It has come to mind that for a small number of people, a dual plug distributorless system would be of benefit.
Some combustion chambers benefit greatly from a delay to the second plug, it can range from 1 or 2 degrees to 10 or so.
Some chambers don't see any benefit, firing both plugs at once is benefit enough. This is easily accomplished with one Megajolt firng two EDIS, or one EDIS firing twice the number of coilpacks.
But what I am thinking is one Megajolt, two complete EDIS, and an external box that would give a fixed amount of delay to the second plug set, via the second EDIS:
From http://www.dainst.com/info/edis/edis.html
"Spark Angle Word Calculation
The algebraic formula for calculating the SAW pulsewidth is:
SAW Pulsewidth (usec) = 1536 - (25.6 x (desired spark advance in degrees))
Range: 64 - 1792us (57.5° BTDC to 10° ATDC)
Resolution: 4us (5/32nd of a degree)
Example:
You want 29 degrees of advance.
PW = 1536 - (25.6 * 29)
PW = 1536 - (742.4)
PW = 793.6
You would send a pulse that is 793.6 microseconds long to the EDIS module.
The EDIS module will do all the work of timing the spark, you just send the advance pulse.
The EDIS has an advance range of 57.4 degrees BTDC to 10 degrees ATDC. These correspond to the SAW widths of 64 and 1792 microseconds respectively."
I am no electrical engineer, but it seems that there are some on here that could help design this, basically a SAW pulse lengthener, of fixed amount, to be added inline to the second EDIS.
Am I nuts, or is this feasible?
Dual plug w/one megajolt
Moderators: JeffC, rdoherty, stieg, brentp
Danny,
was thinking about your twinplug problem while in the shower (!!) and had a thought. The EDIS spec is such that the module does not require a SAW pulse on every PIP event- it is supposed to 'remember' the last SAW value sent to it, at least for a few ignition events.
So- what could be done is that the SAW output could flip-flop between EDIS modules. One module would receive one ignition advance and the other receives an advance word with some configurable advance offset. For example, if the offset was 5 degrees retarded, the 2nd set of plugs would fire 5 degrees after the first set.
Some simple external hardware would be needed to select which EDIS module gets the SAW pulse. A couple of user outputs could be purposed for doing this selection, and some simple additional logic could be implemented to route the SAW pulse to the selected EDIS module.
Seems feasible to do!
was thinking about your twinplug problem while in the shower (!!) and had a thought. The EDIS spec is such that the module does not require a SAW pulse on every PIP event- it is supposed to 'remember' the last SAW value sent to it, at least for a few ignition events.
So- what could be done is that the SAW output could flip-flop between EDIS modules. One module would receive one ignition advance and the other receives an advance word with some configurable advance offset. For example, if the offset was 5 degrees retarded, the 2nd set of plugs would fire 5 degrees after the first set.
Some simple external hardware would be needed to select which EDIS module gets the SAW pulse. A couple of user outputs could be purposed for doing this selection, and some simple additional logic could be implemented to route the SAW pulse to the selected EDIS module.
Seems feasible to do!
Sometimes I get a eureka in the shower too! I just have to write it down immediately or I forget(CRS). Ah, the old flip-flop trick 
That would work, as long as before 5 events take place it gets a new pulse. Not trying to make more work for you Brent. That is why I was thinking an external box to the Mega, it is an extremely limited app for only a few people. Could it be easier to read a pulse, add a certain amount to it, and then send a slightly longer/wider pulse to get a couple degrees retard?
That would work, as long as before 5 events take place it gets a new pulse. Not trying to make more work for you Brent. That is why I was thinking an external box to the Mega, it is an extremely limited app for only a few people. Could it be easier to read a pulse, add a certain amount to it, and then send a slightly longer/wider pulse to get a couple degrees retard?