Ford injectors (& Question) MORE

[Dave Zug]

Sorry to keep this going, but I have more:

I analized the pulse widths that I am getting (383 CI TPI w/ stock 22#
injectors, 360 HP est) verses the max PW for a range of  RPM's (3600 - 5500
: My "drag zone") and although I am seeing 13  ms pulses, they occur in an
rpm range that allow a maximum of 16 msec thus my duty cycle times are FINE!

RPM/ MAX Allowable PW/ Measured PW /Measured Duty Cycle

3600     16.7     12.9     77.4
3750     16.0     12.3     76.875
3900     15.4     12.4     80.6
4050     14.8     12         81
4200     14.3     11.6     81.2
4350     13.8     11.2     81.2
4500     13.3     11         82.5
4650     12.9     10.8     83.7
4800     12.5     10.5     84
4950     12.1     10         82.5
5100     11.8     9.3     79.05
5250     11.4     9.2     80.5


Conclusion:  My stock 22# TPI injectors are correctly sized for my stroker /
large tube / header / 13.1 E.T. setup, even though I have PW's that are over
10 ms.

Right or Wrong???
TIA (again)



----- Original Message -----
From: Dave Zug <dzug at delanet.com>
To: <gmecm at diy-efi.org>
Sent: Saturday, August 19, 2000 2:19 AM
Subject: Re: Ford injectors (& Question)


> Thanks Roger.. I see my mistake.  Much thanks.
>
> ----- Original Message -----
> From: Roger Heflin <rah at horizon.hit.net>
> To: <gmecm at diy-efi.org>
> Sent: Friday, August 18, 2000 3:50 PM
> Subject: Re: Ford injectors (& Question)
>
>
> >
> >
> > On Fri, 18 Aug 2000, Dave Zug. wrote:
> >
> > >
> > > So if I have this right, Let me write this in other terms...
> > >
> > > Lets say for example a car cruising is doing 5 ms pulses at a constant
> 6000
> > > rpm (for math's sake).
> > >
> > > Its pulsing like this:
> > >
> > > each bit is 0.5 ms: (2 crank revs = 1 cam rev =20 bits). 20 ms time is
> > > represented (4 engine "strokes").
> > >
> > > 1111100000 1111100000 1111100000 1111100000 Left
> > > 0000011111 0000011111 0000011111 0000011111 Right
> > > <----------10 ms--------> <---------10 ms--------->
> > >
> > > Alternating left and right for HALF the PW time each 10 ms to complete
> the
> > > full PW time within one CAM rev.
> > >
> > > Then we go to WOT and for math's sake lets say we gain no RPM's or
> fueling
> > > requirements.
> > >
> > > Its pulsing like this:
> > >
> > > each bit is 0.5 ms:
> > >
> > > 1111100000 1111100000 1111100000 1111100000 Left
> > > 1111100000 1111100000 1111100000 1111100000 Right
> > > <----------10 ms--------> <---------10 ms--------->
> > >
> > > Now to the (almost) REAL world.. Heres what WOT looks like (constant 9
> ms
> > > requirement) :
> > >
> > > each bit is 0.5 ms:
> > >
> > > 1111111110 1111111110 1111111110 1111111110 Left
> > > 1111111110 1111111110 1111111110 1111111110 Right
> > > <----------10 ms--------> <---------10 ms--------->
> > >
> > > The above example has the injectors on IN UNISON for a total of (0.5
ms
> *
> > > 18) or 9 ms over each 10 ms (1/2 valvetrain cycle) period. the listed
PW
> > > then repeats itself for the next 10 ms with no recalculation taking
> place
> > > (??) to complete the valvetrain cycle.
> > >
> > >
> > > Do I have it right?
> >
> > Close, I believe they actually pulse the given pulsewidth at once, so
> > when the computer says 9ms it actually opens it for 9ms, and then
> > closes for 1ms, not (4.5ms, close .5, 4.5, close .5)   On the
> > sequential cars it would list 9ms as 18 ms, and keep it open for I
> > believe the entire time or almost the entire cam rotation.    I don't
> > know if they alternate banks, I would need to look at the code to
> > figure out that and how exactly it compares to the actual cylinder
> > timing.  My guess is that it may not really even match up consistantly
> > with the cylinder timing, just close enough, I suspect also since the
> > injectors have difficulties with being closed for short periods of
> > time that that may be the reason to not even try to time single
> > cylinder events, since this would required bigger injectors to avoid
> > getting the close time too low.
> >
> > Roger
> >
>
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