Please add questions and comments in the discussion section of this page or in a different writing.
My setup
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)
It will be a mono-fuel car at first and later on I'll try to develop a second base map for the petrol injectors. (discussion is below)
Further thoughs/info
- LPI is not an option for me. It's not realy reliable and is much more expensive.
- CNG isn't an option too cause it's to different from LPG and it to hard to refuel over here in my country. In my opinion it doesn't has enough pro's right now. I can name more but I guess this will suffice.
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 and effectively a runtime-adjusted "req_fuel". The flow is linear with the pressure (if injecting gas; proportional to the squareroot if injecting liquid!) thus injection duration can be calculated.
Discussion section
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. (This should be possible.) That way you "just" change
- injector PWM (pulse wide ...?)
- injector-opening parameters
- most maps should NOT need adjusting
- VE does not change when switching fuel
- lambda : might make sense to change (for gasoline-LPG, and certainly for gasoline-alcohol)
- Maybe higher ignadv with LPG (isn't really nescessary)? knock_default_retard should be sufficient for that
maybe interresting:
http://www.altenergy.com/propaned.htm#Properties of
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