[BuickV12]

I need help on what to do and where to go.
My aim is to get a BMW engine to run with the original 60-2 crank trigger wheel, and a (six cylinder) distributor.
As the engine in question is a twleve cylinder, I just have to do everything twice, as it has two distributors, and also two crank trigger sensors. Of course a way to make these systems work exactly alike bu coupling them togheter in some way would be a bonus.
I'm going to run carbs, so no fuel injection will be involved. Either TPS or intake vacuum for other than revsensitive timing.

This is what it looks like, one distributor on each camshaft:

[BuickV12]

OR. would it even be possible to use one speeduino to drive both coils by alternating firing 60 degrees for two channels?

[PSIG]

Is this the layout and firing order? It's late and I'm tired. Somebody confirm or reject that it can be run as wasted-spark firing pairs:
1+11/4+10/9+3/8+6/5+7/2+12
One 2560 ECM with 6 ignition output channels, no fuel. If you want fuel, add a 2nd ECM with paired injectors. @pazi88 has a 6-out board that could be adapted in code perhaps. Of course, if that's valid, then the two distributors could be sync'ed to fire the same pairs on just 2 channels at crank speed (probably not what you'd want to do). It doesn't have offset-ground crank throws or anything, does it?

Seriously, I'm done for the day. Somebody take a crack at it.

V-12_ordersm.jpg (39.43 KiB) Viewed 2046 times

[Jama]

This is similar to the 1UZ V8 with 2 independent bank driven distributors.
I wrote a new output mode for a client, with one which fired ignition channel 1 and 2 alternately.
It was tested on the bench and looked good, I sent him the firmware to test and never heard anything back.
So banked distributors are certainly possible.

The Speeduino firmware currently only supports up to 8 cylinders.
12 is not a valid option, so I imagine that itself would need a workaround first.

[PSIG]

A 12-cyl divisor with (otherwise) sequential 6-cylinder setup (with the other 6 along for the ride) is what I'm thinking for the math. The 6+6 would require a cycle signal and coil packs.

Alternatives could be to fire alternately on a similar divisor for 6-per crank rev (no cycle signal). Or to run it 6-cyl on current code with half-tooth-count settings and cam signal (e.g., new wheel 60T as 30/1, not 60-2 wheel), so it thinks it's had 720° in one rev (6 wasted/paired triggers per rev). Alter the other settings to fit as a 6-cyl. It doesn't know how many cylinders it has, and just does what it's told every 120° (actual 60° per-rev), but timing values would be halved.

In any case, this highlights my approach again that ignition and fuel should each be on separate routines or ECMs, not mixing 2 ECMs for ignition (half IGN and half INJ on each ECM ). I have no problems with losing either ignition or fuel, but not half of each with the other half forcing the engine to run when it's confused or crippled with half it's timing wrong or whatever. Easier to tune, also, when each is all on one ECM (IGN or INJ). I'd suggest making one choice of path, then running that down to the finish, or it will get too confusing to mix options. For me it would be a new wheel and 6-cyl settings for shortest path with compromises, but that's my reasoning. I need more coffee. Do your thing.

[BuickV12]

@PSIG

Somebody confirm or reject that it can be run as wasted-spark firing pairs:

It wouldn't work. The distributors are offset, so there wouldn't be anybplace for the wasted spark to go.

@Jama
This is what I was thinking. One bank has to be timed to fire three times per revolution. So this would mean a normal ingintion sequence for a six cylinder.
Since I'm running two coils and distributors, only the three signals per rev is needed to fire. The distributor will do the rest. This on one channel. Then the second channel would be timed exactly 60 degrees later, exactly in the middle between firing the first channel.

This would mean three ignitions on one revolution of the 60-2 wheel, and another three one the second channel delayed.
Is it even possible to do something like this?

[PSIG]

@PSIG

Somebody confirm or reject that it can be run as wasted-spark firing pairs:

It wouldn't work. The distributors are offset, so there wouldn't be anybplace for the wasted spark to go.

Two different scenarios—coil packs and distributors. Question is for either, and coil packs should be doable at a minimum. Are the distributors adjustable, allowing sync? Keep in-mind they would have to be re-geared, and so not an attractive option for many.

[BuickV12]

Two different scenarios—coil packs and distributors. Question is for either, and coil packs should be doable at a minimum. Are the distributors adjustable, allowing sync? Keep in-mind they would have to be re-geared, and so not an attractive option for many.

My bad. I thought you meant driving both distributors with wasted spark.
And yes, wasted spark would work, with six coil packs.
The distributors can't be adjusted, the adjusting is done by soft ware, and of course, that's where the Speeduino would come in.
In either case the coils will have to fire three times per revolution on one bank ( coils 1-3) and thee on the other bank (coils 4-6) This will probably necessitate the use of a total of six channels, whereas using distributors, two channels would suffice.
So still wondering if a Speeduino could handle one or the other of these possibilities.