[Diy_efi] Intro, and q's about fuel economy

[James]

On Sun, 15 Dec 2002, William Shurvinton wrote:

> As for the actual EFI. If you are not after meeting any emissions regs
> you can build very simple EFI. Have a search on how some of the old
> Bosch stuff worked. K-jet was all analogue. You can implement a
> workable EFI system with a 555 and a few op-amps if you approach it
> correctly. Especially if you only have a limited number of operational
> states.

Ya, there's no emissions stuff.  We run with a straight pipe and no
catalytic conv.

The plan right now is to use a microcontroller board (based on Siemens
167CR) to do everything - where "everything" is a/d converstion of the EGO
and injector actuation.

An all analog system is certainly intriguing.  I think it'll be easier to
develop the system with a programable board, but if we get everything
working before the competition, I'll start looking into a simpler system.

> For reading on economy it is also worth having a read of anything you can
> find on aviation engine control. As planes in level flight are effectively
> at a single load point and there is very little qualified in terms of EFi
> the pilots manually lean the mixtures to get best BSFC, which is not
> something you can easily do with a car. If I understand it correctly you
> want to open the throttle whilst leaning the mixture until you reach the
> lean limit or WOT.

Oo, that's a good suggestion for research.  I think it's applicable... in
the competition, we open the throttle, get the car to x mph, then kill the
engine and coast to y mpg, then start the engine and run up to x ... etc.

What're BSFC and WOT?

-j



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