Injector Confusion

[CSH-HQ]

YES, there are some real junk ones (FMUs)!!.
Yes, you have to be 10x more "expert" on fuel system capacity/pressure.
(Also, why I kept saying -10 for supply, and -6 (MIN) return).  You have to 
have things right for high demand.  This using pressure for quanteeing fuel 
delivery is an evil item in my book.  I can not justify the math/science in 
it, but it does work.  When ya get really really picky you can pick up fine 
points, ie, on one bypass system I was changing the bypass hole .003-.005" 
at a time.  Took probably 20 passes to get just that right..
But, there is no other way to get the "dynamic" range out of an injector.
They are "new" to the market, and I hope things get better, I have heard 
of a limited production one, that is supposed to be right.
  I'd just much rather use a longer on time, I've seen some injector flow
stuff for short injector pulses, and they all leave alot to be desired in my 
book.  ANYTHING, that can be done to hold an injector on like 1.6+msec., at 
idle is worth it as a min. for what I've seen.
  This trying to get a decent idle at 1.1s is just too much grief, or maybe 
I'm getting old.
Grumpy
  You numbers may vary, my stuff ain't what you'd call lab grade.
What's an, INSTAAFL?.


At 12:19 AM 11/12/99 -0500, gmecm at efi332.eng.ohio-state.edu wrote:
>Bruce,
>I have some experience with these with FMUs on supercharged/turbocharged
>applications, and I hate 'em.  IME, they are unreliable, not very linear,
>and not very repeatable.  They depend on restricting the return line for
>their pressure rise, and what happens at WOT?  You're using most of your
>fuel and not returning much, and the pressure drops...Boom.  We just pitched
>the one on my friend's Powerdyne supercharged BMW 2002 , and the fuel curve
>is much more consistent without it.  We did have to go up considerably on
>injector size; TNSTAAFL, you know.
>
>Kendall Frederick