MGB

[Peter Wales]

>Well, OK I'll not be modest...

Good, at least this should be fairly simple to start with and get more
complex as you choose. The object is to create an analogue injection system,
and then develop a computer control system. The system I am proposing will
fit any car, with any number of cylinders and any number of injectors. It
will give the same amount of HP as any other system, and the driveability
will depend upon exactly how much work you want to do on the microprocessor
end. I have used this system to generate over 300Hp on a Turbo Starion Race car.

However, lets start at the simple part to get the engine running. First, you
need to acquire the air mass meter. It has 4 wires coming from it, Gnd,
+12v, output and a diode for air temperature compensation. Ignore the diode
for now. The output needs a pullup resistor to supply and this can be 4k7.
Now we have a square wave which increases in frequency with the air flow.
You need to feed the square wave into a Cmos monostable such as  a 555 (It
must be  Cmos). The potentiometer on it needs to be able to adjust the pulse
from 2 to 5 mS and this will be the mixture control. The voltage control
will come from our CPU later so just decouple it for now. The output needs
to go into a Darlington driver and this must be rated high enough in voltage
to withstand the back EMF generated by the injector. (TIP 121) The injector
may need a resistor in series with it if it is low impedance. If it is, grab
the ones from the Starion, they are about 4-5 R. 

Make it run and see what happens. If it is too rich, you may need to put a
divider after the air mass meter and before the monostable. On the race car
I ended up with a divide by 12  and 2 1000cc/min injectors (100lb/hr)

If any one else is proposing to try this system and they want to use
multiple injectors, use one 555 for each injector and let them all run at
once. You will need a divider and if you are clever, you could make a
sequencer so that each injector fires at a different time from any other.




>At 6,000 RPM this comes to 5 MS if fired once/cycle...
6000 RPM is 10mS
every other cycle is 20mS

 
>Is there enough info. on the system to enable me to figure out what to
change to adapt it to my car???
>

You need to change nothing on it because it is simple. The changeable part,
you are going to build. With the tools you have you can test everything on
the bench before fitting it to the car.


>>All and all sounds like something to look into.....Recommended
reading???...I'll stop by the local PEP Boys and see what the Haynes manual
on these cars has to offer.  They usually have good wiring diagrams, etc.....


I hope you can find something. I have the workshop manual in England and can
get it sent over if I need it.


Have a good Christmas



Peter Wales
President Superchips Inc
Chairman Superchips Ltd        "Timing is everything"