Reply to Cilff Ducharme [not private]

[john carroll]

Cliff Ducharme and any one else

Cliff, I could not seem to make your Email address work and am replying 
here.

I have built a number of sucessful aircraft ignition systems and am about 
to build an injection system.  Aircraft  concerns and needs are so 
different from the others on DIY_EFI that it is a different world.  It is 
reassuring to see that someone else is concerned with aircraft engines.

The system is base on GM DIS hardware (distrbutorless ignition 
system).  I figure that if GM will build a base and coil system that works 
and controls so nicely that there is little reason to reinvent that part of the 
system.  The GM hardware uses a bunch of power, but works down to 9V 
or less.  This allows the cars to start on cold mornings when the system 
voltage is pulled down from heavy cranking.

My controller based on Signetics' 8X550 processor.  This 8031 
derivitive is plenty fast and has sufficient AD input to process every input 
I care about.  I use a Harris automotive part in the controller to watch for 
pre igniton and dentonation.

The the system uses a timing disk mounted behind the prop for timing.  I 
keep one magneto functional for a backup.  At present spark timing is a 
calculated function of  MAP and RPM.  There is no mapping and the 
calculations can be modified easily.  The timing is dropped back if 
preignition is sensed and all advance drops out if the engine over revs.

Various operational parameters are output to a four line by 20 character 
LCD.  The data is also continuously dumped to a serial port.  Several 
reassignable buttons can be used to change the operation in service.

This system would great job of running your lawn mower.  The GM 
module will work fine with just one coil installed.  You could get to work on 
the fuel injection and forget the ignition and controller development.

I have some ideas, developed over a considerable period of time, about 
how an aircraft efi should work.  I really want to work on the injection 
system but find myself short of time. 

 
Would you want or appreciate more discussion? 
What are your goals for the system your are developing?
What are your hardware and software skills?
What test facility do you have available?

I am an EE, '70 with too much to do.  I am good at prototypes and 
machine work.  I have experimental catagory aircraft available for testing 
and my friends are also pilots who have become sympathetic to testing  
equipment.

I prefer 8031 type controllers.  My software is a set of assembler 
modules tied together with compiled basic for the IO to the LCD and 
serial port.  Ignition management takes up about 15 percent of the 
controllers time at 3000 rpm.  The controller is running at 12E6 now.  It 
could be pushed to 16 MHz easily.

John Carroll
307 674-8469
fax   674-4510




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