Twin plug firing and standalone management.

Does anyone have any experience in fitting a standalone ECU to an engine with twin spark plugs? My OEM ECU fires the plugs sequentially, but to achieve that I would need an ECU with 16 ignition outputs which I'm struggling to find.

How would firing the spark plug simultaneously effect drivability and hp? Would piston crown design need to be change from OEM?

G'day M119K.

I haven't got any experience with twin spark engines that aren't rotaries, but would it be possible for you to move to a wasted spark setup, and halve the number of required ignition outputs?

Finding an ECU that supports twin spark with different ignition timings without a bunch of custom coding would be the next trick.

Are you referring to a Hemi or MB motor?

I recently did a KTM Super Duke 1290 V-Twin motorcycle engine that has two COP / spark plugs per cylinder. I was able to get the engine running just fine using a single plug or dual plugs firing simultaneously -- however, I had to use a separate ignitor (with two separate ignitor devices) for each plug in a single cylinder. If you wire both coils in parallel to one ignitor, then the current is doubled, and the ignitor limited the current before the coils reached maximum flux. Easy to see on an oscilloscope with a current probe.

Sometimes engines with a high # of output requirements are handled with two ECUs - one for each bank. Perhaps you could do that similarly for the second plugs, just use a second ECU with a second plug ignition map.

Hi David, I recently just built a custom motorcycle using a KTM 1290 engine.

Didn't even think about the built-in immobilizer in the ECU.

So now I have a motorcycle I may not be able to run unless I can get it working with a standalone ECU I think.

I'm pretty green to ECUs and engine management, I'm currently looking at the ECU Master Black since it has a DBW built in.

I'd love to talk about how you were able to get your 1290 running and performing.

Thanks

It was a customer project, but I remember a few things. I had forgotten about the two ignitors... I ran sequential, and had to configure the forward cylinder map sensor to sync the 720 deg cycle on start up, after that the engine runs just on the crank sensor. I did my own injector characterization by running injectors tests for a known period of time and measuring the output. I used a MoTeC M130 running GPA firmware.

My contact info is on our website: https://shop.veracitydata.com/pages/about-us

Sequential is often used for emissions, to get a 'cleaner' burn, especially if very lean mixtures are used for light running and/or to have two flame fronts that burn faster and allow less timing to be used for better torque.

You should be able to tune the engine perfectly well firing both coils at the same time.

If you do go that route, I'd suggest using a dual output coil for each cylinder - that way you only use one output for two spark plugs. Perhaps it would be easier to package with four of the four cylinder coil packs designed for wasted spark?

Hmmm, thinking on it, you could pair up the leading, and the trailing spark plug timings on complimentary cylinders, by running them in wasted spark form - ie, x coil fires the leading on one's compression and the other's exhaust stroke, and coil y does the same for the trailing coil firing.

Oh, that's basically what David said.

A V-Twin doesn't have even firing (like every 180 deg found on a 4 cylinder inline or opposed engine), so you need to work sequentially. with specific crank angles for both injection and ignition firing.

As above for power tune paired output per cylinder should be fine, have spoken with guys doing that on bikes and Porsches without issue.

thanks for all the input and feedback.

I'm very new to all this, hence why I'm here trying to get classes and learn.

so right now its all a little foreign to me aside from what I've been trying to read and watch on youtube.

for now, i know that i need to verify the trigger wheel on the bike will work (I've verified there is only a crank sensor, no cam sensor)

i know the bike has 2 spark plugs per cylinder, can i not fire both spark plugs at the same time using the same ignitor signal or do they need to be timed separately?

based on what i was reading on wasted spark, would i need to fake that i have 2 extra cylinders?

A bit of confusion there, I thought it was clear I was referring to the V8, not the m/cycle engine.

But for the twin-plug m/cycle, IF it's permissible to fire both at the same time, and I can't see a reason not to if already altering the OEM spec', a dual output coil for each cylinder will work perfectly well, and only need a single signal.

thanks for the help!

i'll probably reach back out once i got the ecu and start figuring things out.

any suggestions on a good wiring kit with all the connectors and tools i'd need.

one thing i hate is starting a project and not having everything i need.

I can't comment of kits, or whatever, but I'd suggest making a detailed schematic of the wiring you plant ot use, with the various connectors to senders, etc, any main loom commections/breaks such as for bulkhead or engine quick disconnects of it's witing, etc. Then figure out the wiring gauges you will need/want to run and figure out the pin ratings/wiring gauge compatability, etc.

When you've figured out those you can then look at the boots, etc, that are going to be required for them.

Then you can order what you expect to need, plus a bit of contingency, and the tools required to do the work.

It can be a big job, and very time consuming, but hopefully it works out.

Yes, especially when the bit you find you need to finish is on 3 months back-order at your supplier, and you have to try and source it from somewhere it's just sitting on a shelf.

I started with an OEM KTM harness, and just replaced the ECU connection and spliced anything else I needed.

@david for setting up the timing with TDC, how was that process?

did you have to tear the motor down much to determine? do you know if the front or rear cylinder is cylinder 1?

i have the repair manual, but i don't remember it being much help other than how to rebuild the motor from scratch.

Like I said it's been a while -- I think that was a project where I used a pressure sensor in the spark plug hole (modified an old compression tester spark plug tube), wired that to a digital input. I also wired the ignition output to a digital input. Then I did a timing test at 0 deg timing, and used the MoTeC Capture Inputs feature to see where the pressure peak and ignition trigger occurred. I then adjusted the Engine Reference Offset and repeated the test until they aligned.

In my configuration, the front cylinder was #1

I may have been off a few degrees, but it didn't really matter as I tuned it on a bike dyno, and it was obvious when I got to the right timing.