Sequential vs Batch Fire

[Bruce Plecan]

> For sequential injection you need big injectors as all the fuel has to go
> through an open valve.

Depends, on some engines the injector fires at a closed valve.
The intake valve is only open for about 25% of one revolution, so when the
DC exceeds 25% then your shooting at a closed valve anyway.  Actually in
some strategies the you have 2x as much time to fire the injector, then in
say batch fire where all injectors fire 1x per crank revolution.

>  Does using big flow injectors have an adverse impact
> on the efficiency of fuel atomisation and controlability at idle?

generally is getting so large that you can't cycle them fast enough at idle
to get them lean enough for a nice ideal.

> I have heard for instance that with my car (365cc/min stock injectors)
that
> someone using 550cc injectors (big h.p. application)  could not get a
smooth
> idle, -mind you that was with a 2-batches of 2 injectors E.F.I setup (on a
> 1600cc 4cyl supercharged engine).

I've heard as a rule of thumb that injector flow should not exceed cylinder
displacement.  Sounds like staged injectors, or a high rate Fuel Management
Unit
Bruce
>
> Nick Parker.
>
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