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'''Engine setup''' * V12 60 degree even-fire * maximum RPM is: ..... (interesting for ignition hardware peak current) * Mounted in a boat (pro-longed high load compared to a car) * Two spark plugs per cylinder, total 24 spark plugs (12 wasted spark coils) ** Bosch Motorsport 3x2 coilpacks (4 pcs required for one engine) ** could be driven from 6 IGBT-s (IGBT can handle the double current if dwell is set sufficiently - not too high, and peak RPM < 7000 RPM) ** Beru 3-channel ignition modules (min 10 mA drive current) * One fuel injector per cylinder ** Siemens High-Z 9 Ohm fuel injectors * 24-1 crank mounted trigger wheel (or 24-2 is also OK) Due to lack of outputs I will handle the engine electrically as an inline 6 cyl. '''Two injectors per injector output.''' * Can one FET handle sustained high duty cycle with sufficient cooling? ** yes, 100% duty upto about 5 (or even 6A) is OK. (the FET's peak current is about 14A but we specify much lower) * Two injectors 9 Ohm results in 4.5 Ohm @ 14 Volts = 3 Amps ** yes, 3A is no problem at all. Make sure to connect flyback wire, of course. '''Driving the ignition modules''' * Six outputs required - using four stepper outputs and two logic level outputs * Drive current requirement per ignition module input is minimum 10 mA ** Driving two channels is a minumum 10x2 = 20 mA up to 40 mA. ** Can the IGBT logic driver handle this? 20mA : yes, 40mA: no (but 40mA should not be needed anyway) ** Suitable resistor values on board?. 255 Ohm is suitable to drive one module, but 120-130 Ohm needed to drive 2 modules (that still protects the i259 chip's outputs). ** I would recommend 6 IGBTs and 2 logiclevel outputs with appr 120 Ohm (=510x150-160 Ohm or so) current-limiting than it can be decided later to use logiclevel or power-outputs. It is also posssible to use 4 stepper (with module driving 8 transformers) and 4 IGBT outputs driving 4 transformers (configured in igndualout, that is perfectly valid and correct for a multispark engine like this !), either 4 driving the 4 modules individually (best setup) or possibly 2*2 connected in parallel (yes, connecting low-side switches in parallel is also safe). * Stepper outputs are powerful, but current limiting resistors (100-200 Ohm) are recommended to protect from short circuits '''Ign output concept proposal:''' While using i259 with lower output protecting resistor (in the 120 Ohm range) might work (or a module that does not have stupidly low input resistance), * '''Marcell would order ignout: 8 powerIGBT (0 logiclevel)''' * and '''use stepper-A and Stepper-C outputs with 100 Ohm protection resistors''' for 2 or 4 external ign-driver modules ('''4 transformers''', 8 sparkplugs), * '''and 8 power-IGBT outputs for +8 transformers''' (+16 sparkplugs) * igndualout is suitable for this, but it also applies to stepper ignouts, therefore (by actuating/consuming the pair of every selected output) allowing only 2 independent stepper outputs (unless firmware mod is applied) ---- '''Wasted spark groups cyls with 360 crankdegrees''' Obvious, but worths to mention: When wiring, make sure to pair cyls that are 360 crankdegrees apart (not in same phase, especially not the 2 sparkplugs of same cyl !). Assuming an I6 with 153624 firing order (to which the big V12 is related), pairs would be: 16 52 34
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