Twin injector system?

[Frederic Breitwieser]

>With all this talk of using twin injectors etc. can anyone tell me the
reason 
>why injectors don't work well with short pulses? I can think of two possible 
>reasons:

Injectors are not a perfect thing.  They are nothing more than a plastic
coated electromagnet that opens and closes a valve, allowing fuel past said
valve.

Therefore, there are four issues that I see.  

1. Opening Delay - There is a slightly delay from when voltage is applied
to when they actually open (very, very small, but its there).

2. Closing Delay - with a spring return, there is a slight amount of time
from when the voltage is removed to when they actually close.

3. Heat - when cycled close to 80/20 (open/closed) the current draw
generates a lot of heat.  Combine that with the engine heat, and the lack
of ventilation INSIDE the injector, well, after a while they bake open.  Of
course, the idea is the fuel flowing through draws some of the heat away,
but this too is not a perfect science.

4. Fuel acceleration.  This is negliable, but its there.  When the valve
opens, the fuel must accelerate out the valve from the applied pressure
behind it, pushing the fuel into the engine.

This is my somewhat educated guess.  The advantages of using two OEM sized
injectors is as follows:

1. One injector runs all the time, for non-boost regular every day driving,
just keeping somewhat of an economical/emissions acceptable standard.

2. The second injector, timed near or at the first injectors timing, fires
to increase the fuel supply as the engine requires it (as in boost, hard
acceleration, etc), gradually increasing its pulsewidth to match the first
injector, which never sees more than 75% duty cycle (random % I just picked
out of a hat).

3. Running two injectors at 75% yields almost double the fuel.  Good for
big turbos.  And two OEM injectors are dirt cheap compared to 80# injectors
for example.  Two 40's can be yanked off something in a junkyard.




Frederic Breitwieser
Bridgeport, CT 06606

Homebrew Automotive Website:
http://www.xephic.dynip.com/

"When in doubt, use a bigger hammer"
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