No Subject

[Bruce Bowling]

Hello, I am new to this mailserver, and I have a LOT of questions
that some of can answer!

I am involved with converting a '72 Camaro from carburetor to 
EFI system.  The engine is a 355 CID small block which has been
outfitted with the usual high-performance stuff.  The engine has
been dyno-ed several times, with the latest peak HP around 425
HP (corrected).  This car is totally "streetable", a daily-driver.
The next goals are to increase the HP to around 475 and install a
EFI system.  The HP increase should be straight-forward to acheive
by inprovements in head-porting and a roller cam setup.  The EFI
system is another story..........

I have been tracking the aftermarket EFI systems available for a
few years now.  Some features I wish to see in a system is adjustablity
of system parameters via laptop, individual drivers for each fuel
injector, etc.  So far, the TEC system from Electromotive seems to be
the closest candidate.  Most of the FI parameters are adjustable,
but it appears to use the "wasted-squirt" where two cylinders are linked
together, so only four drivers are needed for 8 cylinders.  It would be
very nice to be able to tailor each cylinder individually, with
"tweek" values that are diferent for each cyclinder, derived from
information from dyno results (like outer cylinders needing a different
A/F ratio from inner ones due to intake manifold flow).  TEC also uses
their own ignition system, wasted spark, which I would rather not use.
The current setup with the Multiple-spark-discharge ignition appears to
be sufficient, so I wonder if the TEC system can run without their
ignition setup, if the TEC EFI computer is provided a spark-event
signal?  Also, is there another candidate I may not know about?

I have also toyed with constructing a EFI unit on my own.  I have played
with the idea of using a 68HC11 (which I have a lot of experience with),
some MC3484S4 injector drivers, and pressure and temperature sensors.
There seems to be some useful pressure transducers from Motorola which
are ready to use without a lot of hassle (electronically).  The goal
over what is available (to my knowledge) is to make a system that can 
have feedback over each cylinder individually.  Why don't existing
systems use thermocouples on each exhaust port providing feedback to
the ECU for each cylinder?  Is this a dumb idea?  The car that this
system would be used is "pre-emissions", so the 14.7 ratio does not have
to apply.

Another question:  After seeing all of the information (or
misinformation) on fuel injectors and performing a few calculations, it
appears I may need to use 50Lb/hr injectors.  Do these injectors
have enought "dynamic range" to allow the car to idle in a decent
manner?  It appears to me that the injector is open a very short
period of time at idle and the injectors may not be stable in
providing the same amount of fuel each and every shot.  Could one
help the situation be somehow lowering the fuel pressure at lower
RPMs and raising it at high RPMS?  Maybe apply a PWM signal to the
fuel pump, with a fuel pressure sensor on the fuel rail, with PID
feedback.  Is this a screwy idea?

ANY information will be appreciated.


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               Bruce A. Bowling
  Staff Scientist - Instrumentation and Controls
 The Continuous Electron Beam Accelerator Facility
    12000 Jefferson Ave - Newport News, VA 23602
                 (804) 249-7240
               bowling at cebaf.gov
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