My project is to turbocharge a BMW E30 325i M20 engine.
Engine specs:
- cyl count=6
- main trigger= 60-2 on crank http://www.vems.hu/wiki/index.php?page=MembersPage%2FGergelyLezsak%2FTrigger
- stock internals
- T3/T4 turbo 50 A/R Compressor, 0.63 A/R Turbine .57 Trim 3" inlet stage 3 wheel
- Oil cooling on pistons http://www.e30tech.com/forum/viewtopic.php?t=5223
- Intercooler will be as big as possible
- Lime green 440 cc bosch high imp petrol injectors
I guess we have a lot in common: http://www.vems.hu/wiki/index.php?page=MembersPage%2FGergelyLezsak
read: original MegaSquirt documentation besides VEMS manual, since MegaSquirt is basically the same.
[GenBoard Version User's Manual]
http://www.vems.hu/wiki/index.php?page=GenBoard
Q: Which parts do I need to get full control of injection and spark?
Assembled v3.3 controller
- ignition driver 8
- Knock and EGT knock and 2 EGT
- LCD and PS2 yes
- MAP connection offboard(electronic)
- primary_trigger VR
- secondary_trigger HALL
I want to use a bosch map/temp sensor I'll get the number later on. Pro's con's mapsensor
- mounting
- line though firewall
- speed
IAT sensor: GenBoard/Manual/IntakeAirTemperature
- faster then stock bosch
Spark control
With your stock 60-2 wheel you can control a wasted spark coilpack directly with VEMS without any additional triggers. You can borrow a coilpack for a 6 cylinder car from an EDIS6 equipped car, like a Ford V6 (You don't need the EDIS module itself, just the coilpack!).
Laptop connection: Basically you use the serial port on the computer, and the corresponding port on the Genboard is either through the smaller EC18 connector or from a pin header inside on the board, which is usually routed to an end-plate in the form of a regular DB9 (standard serial RS323) connector.
LPG section
I wil be running LPG with a Vaporised Sequential Injection System. http://www.prins-lpg.com/en/products/vsi/index.html
Stage one plans:
- Use Prins vapouriser, injectors and use VEMS to control the amount of fuel.
- LPG doesn't have a steady fuel pressure in the fuel rail. So I will have to make req_fuel scaled according to the 1/sqrt(lpg_pressure). There is no need for an extra variable, since req_fuel is already there! All that is needed is 1 bit to enable the lpg_pressure dependent scaling (maybe 3 bits so the mcp3208 channel can be chosen: well, 1 byte might be more future-proof). You can add a variable at the end of config. Actually, the same would be suitable for gasoline as well, if one trusts his fuel-pressure sensor.
- Pressure in the fuel rail isn't constant because off the liquid to gas transformation and the volume flow trough the vapouriser. By a fuel cut off, liquid gas is still in the vapouriser and increases in volume building more pressure. These effects are much to big to compensate with a pressure tank and are much bigger then the pressure fluctuations in a petrol injectorrail. A solution for this might be adding a pressure regulator with a blow off valve in the injectorrail. Or atleast a pressure relief valve set at about 4 bar. Problem with a higher pressure then 4 bar the injector won't open anymore.
- Where to blow off if pressure is too high? I guess no one wants it go to free air. The gas won't go back to the tank fulfilled at 200 bars. How do factory systems overcome this problem commonly? Limiting the regulators flow depending on the (regulated) pressure might be a solution?
- Why not to free air? Connect a hose to it a let it flow to a safe place like the wheel arch. This will never be much LPG and because you are moving there are no problems. [Economy and fuel-economy. This is a bad solution IMHO] I know this would be the solution by LPG-systeems-developers. But due to emissions and regulations they can't do this. Their blow-off valve is redirected to the intake manifault. [Haha, that's what I call unmeasured gas :) ]
- The pressure in the tank will never exceed 25 bar there is a pressure release valve on it which opens at 25 bar. This valves redirects the pressure to the open air! [Ooops, I thought about CNG pressure, you're right. 25 bar is not too much! I guess you can find injectors withstand that pressure. Look for diesel and modern gasoline (f.e. on FSI) engines! Direct liquid injection without pressure regulation (but measurement of coz) -that's cool :)]
- Only CNG tanks have higher pressures like the 200 bars you are talking about. CNG (Compressed Natural Gas) and LPG (Liquid Purafied Gas) are very different! The pressure in a LPG tank at minus 20 degrees celcius can be as low as 2 bar. Depending on the amount of propane/methane mixture.
Future problems:
- Injectors are to small.
- Vapouriser might be to small. (Might have to use two of them.)
- I don't know customers prices, not my department :) You can send them an e-mail if you want to know. -Did that, no answer :(
Second stage:
- Add an other base map to Vems. I want to be able to run on petrol too.
- This option isn't available jet
- Running both high and low impedance injectors.
links
BMW on LPG: http://zymo.homemail.com.au/bmw2.htm
More info on nitrous systems: http://www.diy-nitrous.fsnet.co.uk/index.htm
VEMS GenBoard/VerThree (v3.x, like v3.3) has 8 output channels that are capable to drive low impendence injectors.