LPG section
I will use the Yellow Keihin injectors from prins along with two vapourisors and MAP/IAT sensor.
It's vapourised injection and supports up to 47 HP per injector garanteed. I will be able to up those limits with higher pressures but there is a limit. In the future I might double the injectors up but for now I won't.
I'll use two vapourisers because I'm afraid to inject liquid LPG and try to stay as far as possible from freezing effects. The vapouriser supports till about 310 hp.
For this to work with Vems I'll have to add two parameters but as I understood this will not be a problem. According to MAP/IAT sensor in rail (Below is more info)
The length for the injector to inject is dependant of:
- RPM
- MAP/IAT (density is dependant of pressure and temperature. The volume is constant so mass of air sucked into the cilinders is known)
- Rail pressure/ LPG temperature (to know the density. The flow is linair with the pressure thus injection duration can be calculated.)
What I mean is, you've got 8 injector outputs, but need 12 injectors (6 LPG and 6 petrol, assuming both are run sequentially). Possible solution is to use 6 outputs in parallel, but wire each injector set through a relay to choose between LPG and Petrol. That way you "just" change
- injector PWM
- injector-opening parameters
- most maps should NOT need adjusting
- VE does not change when switching fuel
- lambda : might make sense to change (probably not for gasoline-LPG, but certainly for gasoline-alcohol)
- Maybe higher ignadv with LPG? knock_default_retard should be sufficient for that
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