Injector Sizing: REALLY dumb question

[xxalexx at ix.netcom.com]

> From:          "Zack" <zubenubi at inetport.com>
> To:            diy_efi at efi332.eng.ohio-state.edu
> Date:          Wed, 26 Aug 1998 15:14:21 -0600
> Subject:       Re: Injector Sizing: REALLY dumb question
> Priority:      normal
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

There is a large pressure drop across throttle at part throttle,
this creates high velocity and helps stratification.
I have also seen early studies, that show best to inject, as for
as possible before intake valve opens.
alex 
> 
> OK, another really dumb injector question.  Granted that when the 
> injector on time gets short, total fuel delivered in the pulse will 
> become more variable as the natural variability of open/close time 
> has more and more effect.
> 	My question is, independent of these considerations, what is the 
> effect of duty cycle?  If during light cruising, the injector is only 
> delivering fuel during, let's say, 20% of the intake valve's opening 
> time, you have this packet of incredibly rich A/F mixture rushing 
> into the cylinder followed by a big gulp of air that has basically no 
> fuel in it at all.  Is mixing inside the cylinder turbulent enough to 
> ensure an even distribution by the time of ignition or is the charge 
> still stratified?
> 
> Z 
> 
> 
> 
> > The root of the thing is that 
> > minimum injector-on time for most injectors is somewhere between .001
> > and .002 second - Less gives erratic fuel delivery. 
> 
>