Re: Injector Duty cycle calculations

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

> I'm probably wrong but with batch isn't 22ms 100% duty cycle at 6k rpm's?

Nope 10 msec
6,000 per min
100 events per sec
each event 1/100 sec
10/1000 =  .010 sec = 10msec
Grumpy

> 11ms is common on my car, (165 ecm) 12 ms is too rich with stock 350
> injectors running at 50 psi.
> Mark
> ----- Original Message -----
> From: <timsiford@hushmail.com>
> To: <gmecm@diy-efi.org>
> Sent: Sunday, July 23, 2000 6:59 AM
> Subject: Re: Injector Duty cycle calculations
>
>
> > >Remember as you crank the pressure up, you reduce the volume that the
> > >pump can produce.
> >
> > Yes - this is why I am thinking of switching to 30lb injectors.  I don't
> > want to run 50+ psi at the rails.  I'm shooting for mid 40's.
> >
> > >I'm dumb, I just remember 10msec at 6K is 100%, so atta glance your
> > >about there.
> >
> > Yes - this is exactly what I am thinking too.  Let me ask you a quick
> question:
> >  When the 730ECM reports injector on-time (pulse width), is this the
> amount
> > of time the injector is on for ONE off-on-off session or the amount of
> time
> > spend in a double-batch fire (off-on-off-on-off) session?  Its just hard
> > to believe that Diacom is reporting 8.3-8.5ms at 6000+ RPMs.  That would
> > mean that my injectors are actually on for 16.5 to 17.0ms per 4 strokes.
> >  That's A LOT of fuel.  Does that sound correct?  Furthermore, when you
> > consider the fact that my 24lb injectors are operating like 28lb
injectors
> > (due to the greater Fuel pressure) it makes 17.0ms of on-time seem like
> > a A LOT for a naturally aspirated 350 for one 4-stroke rotation.  Any
> thoughts
> > on this?  What does your EFI experience say?
> >
> > >If the 10 is correct, then he's not in a SEFI mode.
> > >10 at 6.5K batch means he's static (injector always on).
> >
> > Or Diacom is reporting wrongly for either his car or for my car.  We are
> > running the same injectors, the same type of intake manifold, and the
same
> > heads.  His car is faster by a bunch (about 75 more hp - track proven).
> >  I would think that he would need to have more fuel and therefore a
> greater
> > pulse width.  This is just very wierd.  I just want to make sure that if
> > I get the 30lb injectors that it is the right decision.
> >
> > >Really sounds like he's batch
> >
> > When did GM switch to SEFI?  I made a slight mistake.  The car is a 1996
> > Pontiac Formula with the stock ECM.
> >
> > >Might give em a call, and ask if there are issues about this.
> >
> > Will do.  Thanks Bruce.
> >
> > >Get some used GN ones, I just bought a set of 6 for $15.  For the price
> > >of checking them, I can't lose.
> >
> > I'll probably go with a set of SVOs.  I can't leave anything to chance
> given
> > my goals.
> >
> > Tim
> >
> >
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> >
> >
>
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