Re: Injector opening time

["Bruce Plecan" <nacelp@bright.net>]

I don't know if there is any data, that is that specific.
I do know that some of the oem gm port injectors will work down to slightly
under  1 msec., and at 6K rpm, you can run 95% DC with some, so what ever
the opening and closing times are they are very short.

Just roughing things out.
At 6K you have a possible 10msec time, and in 5% of that you can still get
an injector to open and close.  that would be 1/20 of 10, or .5 msec for an
open and close. or .25msec for a open or close average event.....

Math ain't my strong point, so someone might 2x me.
Again, just a seems logical to me thing, since I know of no other info..
Grumpy





> I wonder if someone could clue me in on the part of
> fuel injector pulsewidth that is lost to just opening
> and closing, no fuel delivered?  What I mean is if
> an injector pulsed for 7 ms had an effective open
> time of 5 ms, then a 12 ms pulse (2 ms opening
> plus two times 5 ms open) would deliver exactly
> twice the fuel of 7 ms
>
> The ECU I am looking at is the old 76 Cadillac analog
> unit.  The pick-and-hold seems to put out a constant
> 1.8 ms "pick" pulse which is fixed in length.  Then the
> "hold" part of the cycle is controlled in length by things
> like the MAP signal.  Extrapolating the absolute manifold
> pressure curve to zero seems to give just about zero
> hold time.  This makes me think the "pick" time is not
> effective in delivering fuel.  I realize a pulse width vs
> fuel delivered measurement would give the answer, but
> I am not set up for this now.  So could anyone comment
> on the ineffective part of the pulse width for both a
> "pick-and-hold" injector, and a DC injector?  Bruce Roe
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