Yet another question for you Turbo Experts.

[Buchholz, Steven]

> This additional injector stuff is great. Keep talking everyone. I read on
> Scott Mockry's site that the fuel distributor in the old CIS cars is
really
> a 6 cylinder piece with one line plugged... (haven't had that part of my
car
> apart yet).
> 
> There seems to me to be 20% more fuel available pretty easily.  Can 20%
more
> fuel feed 20% more boost ? I think so. Lets see, 230 x .20 = another 46.
> 230+46= 276.  The impressive part would be the torque increase. Not bad,
now
> your starting to use that K24 (or almost a K26). Could that line be
> controlled with a solenoid that is activated only a pre -set elevated
boost
> pressure and/or WOT ?  Everything in essence would still be controlled by
> the already modded computer.  Sounds sorta straight forward ? Certainly
not
> perfect, but I'd be willing to bet that the initial rich spike caused as
the
> line is triggered to open (and maybe before max boost is reached) wouldn't
> adversely affect the car's performance.  Turbos like a little extra fuel
> when they're really working...Could that line be split into several / many
> smaller injectors so proper fuel distribution could be achieved ?      ?
> Well its an idea anyway...

... the thing here is that this is fuel that is metered all of the time
based on the airflow sensor position ... not clear to me that this is at all
what you are looking for.  Why drill and tap the extra port ... you probably
would need to install that sixth diaphragm and tune it to match the other 5
as well ... when all you're looking for is something to add fuel at WFO?  

One thing I don't know is how much additional fuel the injectors that are
there could provide ... I'd imagine they're pretty close to saturated, but
they can't be running at 100%.  If you were thinking about a way to kick a
valve to richen the mixture, an obvious thing to me would be to have some
way to lower the control pressure.  This would allow the airflow sensor
plate to move farther and apportion more fuel to the engine.  

As I see it there are three levels that can be considered for beefing up the
fuel on a tweaked engine.  

The first level is to leave the basic system basically intact and monkey
with its parameters to provide more fuel.  Given that we are talking about
either MC or WX engines the obvious variables are: control pressure, the
duty cycle on the OXS frequency valve and the system pressure.  I suppose
that one other possibility along this line would be to find compatible CIS
injectors that have a higher flow rate ... AFAIK that was talked about, but
I've never heard that this actually provided any benefit.  I don't know how
willing I'd be to increase the system pressure ... it is already pretty
high.  It actually should be fairly easy to add something to force the OXS
Freq Valve to run full rich and to force the control pressure down at WFO.  

The next stage is to find some way to add fuel using some auxiliary fueler.
This is where most of the discussion has been to date.  There are a few
products on the market which will augment the fuel to the engine at WFO.

Finally, the last stage would be to eliminate the entire fuel system in the
car and replace it with a system from a newer car or an aftermarket unit.  I
guess Javad's system is a bit of a hybrid between these last two, as it
retains the factory CIS system but he has added a separate pulsed injector
EFI system in parallel that can be activated under boost, but is a bit more
complicated than the "microfueler" products. 

Steve Buchholz
San Jose, CA (USA)