Members Page/Jan Saenen - VEMS wiki www.vems.hu

MembersPage/JanSaenen (2006-03-16 04:43:08)

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.

Problems:

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.
- To decrease the effect of pulsing rail pressure a small temporary tank attached to the rail might help, and using sequential injection is preferred more than using all/banks the same time.

-I didn't mean the effect of a pulsing rail by opening the injectors like in a petrol fuelrail. I ment the pressure isn't stable like in a petrol fuelrail because it works different with LPG. That's why the original Prins management works with a Map/temp sensor in the fuelrail. LPG is much more temperature sensitive then petrol. This is the difference between petrol and LPG. Thus I will need to add a variable. Is this possible with Vems or can I change an existing variable for my use?

Future problems:

The biggest injectors support only 50 hp per cilinder. This can be raised by raising the pressure. Problem with raising the pressure is the injectors only open till about 3.5 bar. By a fuel cut-off pressure will raise very fast and will exceed 3.5 bar very fast. Solution will be something like a pressure release valve.
- The guy here http://zymo.homemail.com.au/bmw2.htm is talking about 125HP/cyl LPG injectors, worth a check...

- Actually that statement isn't true. I was talking about those injectors. They only make 50 hp per cilinder with the standard Prins management system. Maybe when you raise the pressure they will make more. I know this for sure because I'm actually send-out by school to the company who made that rail. I'm at Prins Autogassystems at this very moment :).

Second problem with raising the pressure is the vapouriser will not be able to vapourise everything so liquid LPG will be injected. This way I will not be able to control the amount of fuel injected precisely.
- that's true. but the system inculdes the filter unit with pressure/temp sensor so you'll be aware when (if) it's happening, and can switch more heat to the vaporiser or lower the pressure. However vaporiser's cooling effect is a great benefit if it's somehow connected with the charge air. (Water IC?)
Develop a second base map and a possibility to switch between maps while driving.

Second stage:

Add an other base map to Vems. I want to be able to run on petrol too.

Problems:

This option isn't available jet
Running both high and low impedance injectors.

Various questions/talk

Or possibly you can bring there commmon household Propane-Butane cans to refill. It's very common here (in Hungary) to run LPG cars on household PB cans, since it's much cheaper. The only difference is the smell (to help police :)

This will be to tricky CNG and LPG is to different for me right now. I may experiment with this later on.
- Household (or camping, etc) gas cans are filled mostly with Propane (~90%) and butane gas just like LPG. CNG (CH4/Methane?) is totally different that's also used in household (heating, etc.) but that's in the form of pipeline not cans (at least here in Hungary). However CNG might be also an option but as I remember for the same weight of CNG gas you'll get 1/5 the range you can drive while LPG gives at least 1/2 the range of common gasoline.

I even thought of eliminating the reductor at all. This way you may can utilize the icing effect of the pressure drop as a charge cooler :)

This won't work with the Prins system I'll use. And it will be close to impossible to know the amount of fuel you're injection with liquid LPG.
- Actually there are systems runnnig on liquid LPG and liquid propane but that's sure it's quite uncommon on vehicles. Interestingly in that case the problem is to keep the fuel in liquid form because propane vaporises easily by heat. They get measurements problems only when the valves are injecting gas besides liquid. (While it's liquid it's measurement similar to gasoline.) Another (the biggest) problem with these systems is finding injectors which keep the pressure of the liquid gas (~200 bar) and still fast.

Q: Can you tell me more about such a nitrous valve?

http://www.diy-nitrous.fsnet.co.uk/index.htm

Low impedance injectors

VEMS GenBoard/VerThree (v3.x, like v3.3) has 8 output channels that are capable to drive low impendence injectors.

I'd love to run the LPG injectors directly and not with a supplementary controller, cause I have total control over VEMS while I only have indirect control of the proprietary controller.

Problem is my 440cc fuel injectors are high impendance and the LPG injectors are low.

I guess I could only run the LPG injectors at first and later on develop a system to run both fuels with VEMS.

Q: there is a difference in the signal to a high impedance injector and the signal to a low impedance injector. How is this configured in VEMS. (Peak and hold for low impedance.)