Injector Pulse Width

[Moofaloof at aol.com]

In a message dated 9/11/00 8:04:05 PM Atlantic Daylight Time, 
scott at scottknight.com writes:

> > I am new to this list after having done a small bit of exploration through
>  > the DIY websites. Are there available anywhere on the sites data that 
> shows
>  > the relationship between engine rpm and injector pulse width.
>  
>  http://www.scottknight.com/calculators/ will have one available.  Keep
>  in mind that it is a simple raw output to show the amount of time for 2
>  engine revs at a given rpm...not the actual time that an injector can be
>  commanded at that rpm since there are many more factors that affect
>  that.  I have seen Al Grippo's formula that takes injector opening times
>  into account and it is much more involved.  There might even be
>  something available from Bruce Bowling's work and hopefully someone else
>  will post that link (I am at an airport without web access right now). 
>  YMMV.

Injector pulse width is, of course dependent on engine displacment, number of 
injectors, and so on.  The thing about inj pulsewidth that surprises most 
people is that it only has a secondary dependence on rpm.   Pulsewidths are 
per engine cycle so at higher rpm you just get alot more of them.  If you 
look at a 1/4 mile run from a late model Chev 350 V8, you will see that at 
idle the pulsewidths are in the 2-4 ms range, and at WOT, they are in the 
8-11 ms range across the rpm range, depending of course on injector size etc. 
 Cruise is typically in the 4-5 ms range or so.  That gives you an idea. 
The primary dependence is on manifold pressure.  RPM only affects pulsewidths 
via its effect on volumetric efficiency... 
jc
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org