Dual fuel PFI rails....

[Frederic Breitwieser]

> No reason it can't be automatic.  If you're using an independent
> switching circuit, maybe you could make it so it watches for rapidly

A few CMOS quad NAND gates, a 324 quad op-amps, a bag of resistors &
capacitors, and eight mosfets from Radio Shack.

One of the quad op-amp follows the MAP signal which feeds another
op-amp, which the threshold is adjusted by a 5 or 10 turn variable
resistor.  Once the threshold is reached, it trips on input on a NAND
gate which the other lead is buffered, but connected to the injector
of the circuit's cylinder.  This way, the second injector only fires
at certain levels of boost, and when the sister injector fires. 
Logical And.  Works well.  The NAND gate then drives the MOSFET which
drives the additional injector, as long as its not a peak and hold
type injector, but a cheesy "normal" injector.

We did this with three stages... Haltach managed, stage I, stage II,
and set two trigger points.  Worked fairly well.  Though just before
the next stage kicks in, the engine ran a little lean, and the ECM
seemed confused at times because its completely unaware of the
additional injectors.

For the Dodge engine, I'd like to use a "7th injector" or "cold start
injector" type of lead to control a batch of injectors that will
enable the a/f ratio to be useful.


-- 

Frederic Breitwieser
Bridgeport CT 06606

1993 Supercharged Lincoln Continental
1989 HWMMV w/turbocharged 500cid Caddy
1975 Dodge D200 Club Cab soon to have 431 stroker + turbos
2000 (I hope) Buick GTP (Mid-Engined Sports Car)