I'll get started with a few basics about meters and injectors and others
will chime in with helpful info I'm sure
First of all you should seperate OEM or in our case ... FORD meters
and
The aftermarket meters like ProM, C&L, and the like from each other
Ford meters are not calibrated to any size injector
If you get right down to it
meters have nothing to do with fuel or injectors
A meter is used to measure airflow
The lightning meter you speak of was designed by Ford to measure the
amount or maybe better said ... the range of airflow a blown windsor
motor will generate
Now ... Having said that .............
Ford knew for that amount of airflow being generated, they would need
an injector size of 42 lbs
The important thing here is this ...
that meter is not calibrated for injectors with a rating of 42#'s
It is the AFTERMARKET industry that started the whole .........
meter caled to a certain size inj thing
The motivation behind that method was to provide a way of using larger
size inj's without having to custom tune OR change the parameters
inside the pcm
Basically what is being done with the meter to inj calibration method is
the meter reports a false reading to the pcm
You no doubt have seen some talk about this and use the wording ......
Cheat Method
It worked pretty well on the Fox Stangs
but
Not so good with our two year run of 94-95 Stangs
We won't go into details but the jest of the matter is .........
the old fox pcm was based upon rpm and our pcm's are load based
Now with the focus on our Stangs ..........
You can say these things about using the cheat method
It works better with the smaller size inj's like 19's and 24's
but
With 30's and above you start to deal with issues
Last but most important thing here about the cheat method
We talked about how our pcm's are load based .........
It just so happens the meter's output to the pcm is used to determine
load and when this reading is off ... The foundation the whole tune is
built upon is all outta whack
When your pcm load factors are not accurate
Well ... the pcm uses load to determine how much fuel/spark to command
This can turn out to be a real ....... cluster you know what
Also ... One tunes the pcm ... not ... the meter
Yes ... You can change the data in the pcm to make the lightning meter
work and MANY have done just that and made it work very well
In other words, program the correct transfer function into your ECU and you can use any size injectors you want with that meter.
Personally, I'd stick with the 42's unless you're getting really silly with power. You can have them tuned via ECU Chip flash to run just as well as the stock 19lb/hr units for every day driving, yet they're support power levels somewhere near the 450-500fwhp range if need be, which is about where most stock short blocks start to get nervous anyway.
Thanks guys for all the insight! that was greatly appreciated! Now My next and last question. Who's the people to see for chip reprogramming? I knew who to see on the modular mustang crowd (sct ect)..My 393 stroker should be built this weekend!