simple analog fuel injection comments from CSH, HQ
garfield at pilgrimhouse.com
garfield at pilgrimhouse.com
Wed Jun 24 16:16:13 GMT 1998
On Tue, 23 Jun 1998 21:46:13 +0000, xxalexx at ix.netcom.com wrote:
>You could also check out old aviation, the mechanical
>throttle bodys, just loaded with all kinds of diaphrams and pressure
>regulation.
It's funny you should mention the "old aviation" mechanical CIS FI. I
haven't commented on this before, since I figured it was way TOO simple
for automotive apps, but our X-aViation group finished a project a few
months back we called KISS EFI or "KEFI", where be developed a simple
analog EFI system with a couple astables like the 555 stuff, driven off
MAP, with a manual mixture control as a trim used to lean at altitude
w/EGT (just like in normal aviation ops). The system was designed for
"dualin", so you could have a redundant backup. Hasn't made it to a
running airplane yet, but sure works fine on the bench!
And Alex, you might be interested to know that there are TWO distinctly
different FI systems from "old aviation" (which term we just laugh at,
cuz there's hardly anything existing in aviation that isn't
"flintstones" -- talk about backward, whew!); one is refered to as the
Bendix system (yup the very same), and it IS complicated just like you
mention. BUT, there is another one called the "Continental" FI system
(cuz it was designed by the aircraft engine maker, Continental Motors),
that is just *dirt* simple, VERY similar to Hilborn style FI, comprised
of no more than fixed nozzles for the injectors, a fuel distribution
block from a spool valve to the individual injector lines, and THAT'S
IT.
Now, the funny thing is, that our KISS EFI project started last year as
a result of a few of us XA guys discussing at a flyin up north, just how
we could make an EFI system that was about as simple and bulletproof as
this Continental system, while avoiding all the special mechanical stuff
and other vagaries of CFI. And that's how we ended up with the
astable-based totally analog circuit that has only 3 active chips,
excluding the INJ drivers, which are Cherry CS-452s.
Just for you analog fans who seem to be outnumbered at the moment by the
programming types: Yes, you CAN often make analog stuff MUCH simpler
than even the simplest micro, but you DO need to speak "solder". So, yes
truly, it's only for the "select few". Hee. Think of use solder-types as
the green berets of diy_efi. B))
Besides, in airplanes, we tend to wanna stay away from computers. Too
many cases of the dog biting it's master, ifyaknowadamean.
Gar
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