Re:

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

Duty cycle, comparison of On to Total event time,  On/Total.   Can't be over
100%.

So if the injectors fire once per revolution, at 3.450, with an on injector
time of 11.6  would be 11.6/17.2   (About 68%).

Bob has a slight error as I see it of adding the two injector times, ie must
have been thinking dual throttle body with 2 injectors, in which case the
total time that both injectors could be on would be 2x as long as compared
to a single injector (or batch strategy),
Grumpy


> I think you're trying to hard, Bob.  The way I understand it, Duty cycle
is
> simply the injector "on" time (11.6 ms) divided by the time it takes for
the
> engine to complete one rev -er, ahem, _cycle_ (34.5 ms)- irregardless of
> injection type, synch or asynch mode, or number of cylinders, yada, yada,
> yada...
>
> That said, I'd like to bashfully change my previous answer from 67% to
33.6%
> Duty Cycle, remembering the old rule that you have 20 ms to play with at
> 6000 RPM...
>
> Oh, alright, who's got the real answer?
>
> Jeremy
>
> >This is what I came up with on a v8 tbi setup
> >(such as '747):
> >
> >3475 rpm @ 11.6 msec inj pulse.
> >
> >-----------
> >
> >3475rpm / 60 = 57.91 rev's per sec
> >
> >1 / 57.91 = 0.01726 sec's per rev, or 17.2 milli-sec per rev
> >
> >v8 = 4 spk's per rev, tbi alternates, so 2 inj cycles
> >for each injector per rev.
> >
> >17.26 / 2 = 8.62 milli-secs between inj cycles.
> >
> >11.6 / 8.62 = 134% duty cycle.
> >
> >For a v6, it's 3 sprk's per cycle. For alternate inj firings
> >per sprk (or bank fired on every other sprk):
> >
> >3 / 2 = 1.5 inject cycles per rev.
> >
> >17.26 / 1.5 = 11.5 milli-secs between inj cycles.
> >
> >11.6 / 11.5 = 100% duty cycle.
> >
> >
> >Corrections welcome. . .
> >
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