EFI newbiee ideas, few questions.

Tom Parker parkert at ihug.co.nz
Fri Feb 25 01:52:22 GMT 2000


Toby Atwater <tob007 at worldnet.att.net> wrote:

>I just discovered this list a few days ago and I am reading everything I
>can. Fascinating stuff. Just got a few questions and "what ifs"

>First off my project is to "convert" a 1969 Austin Healey Sprite (1275 cc
>inline 4) to Throttle Port Injection. I would hopefully keep my carbs and
>just use them as throttle bodies and fabricate a piece that would fit
>between the carb body and the manifold with the injector. X2 for both carbs.
>I'm still in the research stage BTW.

I won't tell you too much about engine control theory, as others here are far
more qualified to speak, but do listen to them, as what you suggest needs
revising a bit.

Anyway, you've got a fairly unique engine in that it has four cyclinders and
two inlet ports. This makes efi a little more complicated than if there were 4
ports (I'm assuming you don't have an 8 port head). The sucking order of the
ports is 1-1-2-2-1-1-2-2...

If you modify an OEM system (GM parts seem to be commonly used here) to work
with your engine then you will have trouble getting it to drive two injectors
in the correct order. I guess you could use a custom driver between the OEM
driver and the injectors to add the signal for the approprate cyclinders to
make one injector behave like two. The problem here is what happens if the ecu
wants to turn on the injector for cyclinder 3 and 4 at the same time?

The other approch is to mount four injectors in the manifold and then the
control problems dissapear. However squeasing four injectors onto an A series
inlet will be interesting.

I'm not saying that this project is impossible, as Rover have done this on
modern Mini Coopers, but they were able to modify the OEM computer.

--
Tom Parker - parkert at ihug.co.nz
           - http://www.geocities.com/MotorCity/Track/8381/

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