Timed mechanical fuel injection

[masmith]

>There is another issue that rears it's ugly head here though, and that's
>injector sizing. For an injector to be able to shoot the required amount of
>fuel into the cylinder for full power operation in just one shot, as the
>intake valve is opening, and get it all in there before the valve closes, it
>has to be much larger than the injector that does the same amount of fuel
>over the course of 8 shots (for a V8) as in the case of the non-sequential
>system. Some would argue that you get better atomization out of the smaller
>injector. In addition to that, some would also argue that each little shot
>gets to hit the hot intake valve and vaporize before the next shot occurs
>and that would also be beneficial. The other part of this is that at high
>RPM full power operation, the on cycle of the injector is pretty much
>constant so it doesn't really matter anyway. It seems that you get the best
>results if you size the injectors so that they are the minimum size for the
>power required, then at full power they have to be pretty much on all the
time. 
>
>Which takes us right back to the beginning where it seems that at low RPM
>you could benefit from sequential, one shot type injection.
>
>I think the best possible system would be one that sized the injectors so
>that they would just be big enough for full on operation at full power
>(non-sequential triggering). But at low power settings trigger them
>sequentially, timed so that they start the fuel shot as soon as there is a
>positive flow after the intake valve has opened, completing the shot before
>the valve closes so air goes in last and therfore, possibly,  getting the
>most miserly milage and emmisions. Then as RPM and power levels are
>increased gradually increase the trigger count per cylinder cycle so that by
>the time you ended up at the full power end of the scale, they were just on
>all the time and JUST supplying enough fuel.
>
>For all I know, this may be what Detroit is doing now. I don't have much
>experience with OEM systems, only with the various after market programable
>one's like the Accell, Haltech, and Electromotive.
>
>-j-
>
>
what about using TWO injectors/ cylinder and somehow gating the second one in 
at higher revs, or loads?  that sounds somehow easier than messing with timing, 
shots per rev, etc. this does not admittedly sound like a DIY system, but......
another idea: one sequential and one firing for all N cylinders
if one really goes nuts, use a ox sensor on each cylinder and control each
injector 
independently.....

Matt Smith - rocket measurement specialist and lurker.
a rocket engine is a very large (actually two - fuel and LOX) fuel
injectors...... :-)

Matt Smith
masmith089 at qnet.com
Mailer Eudora 1.4.4