EFI for a Mini

[Andrei G. Chichak]

At 19:06 4/21/95, G P J Collingwood wrote:
>Does anyone have any ideas on which current fuel injection systems could
>be modified to run on a 1400cc Mini engine, and then remapped for it?
>
>Giles
>Durham/Hexham UK

   A brilliant question and one that has been much on my mind.  I want to
put EFI on my 1330 Cooper 'S engine and I have pretty much come to the
conclusion that I am going to have to build it myself.

   I figure that a manifold could be cobbled together with two injectors
per port, a couple of dual head coils, add an oxygen sensor in the centre
branch of the exhaust, a crank sensor on the pulley, and one in what's left
of the dizzy for cam position, add the obligatory throttle position sensor,
and some sort of mass air flow sensor, temperature probe, knock sensor, tie
it together with a bunch of glue, control it with a 68HC11, and POOF no
more S.U. carbs or Lucas ignition (in theory).

   I have seen pictures of the Weber and Luminition systems installed on
Mini's, but neither of them use any form of mixture feedback loop, plus you
have to take them to a stockist to get them tuned to your engine.

   Many moons ago, I believe, Steven Ciciora suggested that I try a Bosch
CIS  system with the swinging gate metering system.   This is quite a good
suggestion if you had access to injectors of the appropriate size.  The
problem comes in with the weird intake system that a Mini has. Cylinders 1
and 2 share an intake port and 3 and 4 share the other.  This makes for 180
degrees between intake cycles then a quiescent period of 360 degrees.
With a CIS system that is always pissing out fuel, the first one to open
will get the accumulated pissing of 360 degrees into the port, the valve
opens for ~180 degrees (for arguments sake we will assume digital valves)
then the valve closes and its buddy opens for ~180 degrees.  Therefore the
first cylinder will run richer than its buddy.

   The solution is to use a sequential system with two injectors per
runner, shooting across the port at the valve.

   You would have to do quite a bit of rework on a grafted stock system, I
suspect, since the capacity is so low, you have a well known knock region
at about 2000 RPM, and you have siamessed intakes and half of the exhausts.

    Enough for now, I have less interesting things that I must attend to.

Andrei

--
Andrei Chichak                   | Information Systems
agc at mercury.uah.ualberta.ca      | University of Alberta Hospitals
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http://cooper-s.uah.ualberta.ca