[Diy_efi] injector advance

[Greg Hermann]

At 1:39 PM 8/6/04, Gary wrote:
>An informative, technical and lengthy discussion was conducted
>in a thread 'sequential injection timing' the last week of July in
>2002, if you have access to the archives.  Many of the more
>knowledgeable members, posting in that time frame, posted in
>that thread.  Recommended reading/studying if obtainable.  Hope
>this turns out to be more than a teaser for you.
>
>GAS
>
The gist of that thread was that if you have some means of getting GOOD
atomization of the fuel, it will give better bsfc and power if you can
inject during the time of high air flow velocity in the intake port.

Injecting against the back of the intake valve is a CRUTCH, used to
compensate for the fact that most electromagnetic injectors do NOT give
good atomization.

Use an exhaust grade material (read more expensive) intake valve, and don't
worry about cooling it.

Evaporating the fuel in the intake port reduces power (fuel vapor displaces
air) and cooling the intake valve reduces efficiency.

Evaporating (well atomized) fuel inside the cylinder once the valves are
closed provides internal cooling during the compression stroke, reduces
negative power for the same, and thus reduces bearing loading !!

You pretty much need to look at something like air assisted atomization for
the injectors to make it work right.

The fact that properly TUNED IR carbys (Webers, et al) will yield lower
full power bsfc than conventional port injectors  at WOT pretty  much
proves the point.

Greg


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