DIY_EFI abilities and older engines

[dn]

> I am also working on my own EST box.  It will use a 68HC11 and interface to 
> a standard HEI distributor with the 4 wire connector. This system will be 
> retrofitted into my 1966 Chevelle.
> 

I'd be interested in a dialog with you on this subject.  I have done a little 
research into the newer EST modules that chevy is using with their EFI systems,
and I think I've found a better unit than the stock HEI module, which fits into  
the stock HEI distributor (I think...).  It has a total of seven interface
terminals, including a spark reference output and input which should be easy
to interface to.  Problem is, none of the aftermarket parts catalogs that I
have have ANY technical info on the module itself (ie voltages, currents, etc.)
that you would have to have to be able to talk to the module.  No alternative
I guess, I will have to buy a Chevy Service Manual for some model which uses
this unit, or just buy one and play with it.  Let me know if you've had any
dealings with this unit.

> I have completed so far:
> about 80% of the hardware design.
> for instrumentation:
>         Dual LCD displays

Why dual?  One for the Wife?

> The frist cut alogrithim will generate spark advance from RPM and MAP
> 

Assuming you don't have access to a dynamometer, how would you generate a
spark timing table?  Also, would there be any advantage to using a MAF
sensor instead of MAP?  I know that the MAF is much more expensive, so
there's a major disadvantage right there.  Using a MAF would allow easier
upgrade to a full EFI system, and I suspect would eliminate a lot of 
guesswork (and CPU time) in calculating fuel air ratios and injector pulse 
widths.

My project hasn't got past the dreaming stage yet, but I plan to get started 
on it this winter and have a prototype ready for spring as well.  I planned
to incorporate a detonation sensor into the system as well, but that is sort
of an optional extra.  The recent series of articles in Circuit Cellar Ink
had some good stuff in them, but they were a bit sketchy in some areas, 
especially in the code implementation.

Anyway, if you are interested in some co-operative developement, drop me
a line.

Regards, Darrell



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