Ignition coil 'relay' for twin plug conversion?

[timz]

I've twin plugged ( per cylinder) a bike engine & I want to use some new high power & tiny coils that I have. ( I don't want to use twin lead coils)
Could I use a circuit with a mosfet & a 100k resistor between source & gate for the switching using the coil driver signal from the stock ecu?
Am I miles off?, thanks!

Ps,
I'm new to this site, great stuff on here!

 

[cowboybob]

This is a useful article.

Especially towards the end.

 

[alec_t]

If the ecu driver signal is intended for driving MOSFETs then I see no reason why it shouldn't be able to drive two with no problem. Not sure why you have the 100k between source and gate? It would be advisable to use a respective 100Ω (or less) in series between the driver and each MOSFET gate (to damp spurious oscillations).

 

[timz]

I've not been very clear on this , sorry. The ecu to ignition coil wires, was hoping to use these to act as the signal for a mosfet.The mosfet than fires the coils with out killing the ecu (ignition only)

 

[alec_t]

Without knowing what voltage/pulse/polarity characteristics the ecu provides directly to the wires going to the coil it's difficult to advise. Can you post a schematic/datasheet of the ignition system?

 

[timz]

Not very clear sorry,

View attachment 63141

 

[Diver300]

The circuit diagram shows two twin-coils in a 4 cylinder, 4 stroke engine. If you are running the standard control unit, labeled "ignitor" on the circuit diagram, which drives the coils, that only has two outputs, one for cylinders 1 and 4, and one for cylinders 2 and 3.

You then need to fire 4 spark plugs at the same time for two plugs per cylinder.

You could just put all the primary windings in parallel. The risk is that you would overload the control unit, or not get enough current to the coils.

The current in the primary windings of the coils has to be limited to stop them burning out. Years ago they were limited by the coil resistance, so they would stand 12 V continuously. More recently, they are limited by current limiters in the control unit, and often the control unit will only turn on for the time it takes for the current to get to the desired level before turning off and making the sparks. Unless you know what is done in the control unit, and the ratings of the coils you want to use, you might not be able to get them to work very well together easily.

 

[timz]

Ok, thanks for your help.I'll do it another way, cheers