Batched Injection / Injector Timing

[Martin Evans]

Batched Injection:
Apart from the fact that a saving is made by using half the 
required number of injector drivers what advantage does 
batched injection offer?

During dynamic load changes if you fire pairs of injectors do 
the optimum fuelling requirements of the engine lag behind 
those that can be generated by the ECU leading to poorer 
emissions and possibly reduced power output?

Injector Timing:
On the subject of injector timing my understanding is that 
if you inject onto a closed inlet valve the flow will be more 
predictable than when injecting during the actual induction 
stroke as the pressure differential across the injector is 
static. If you take this into consideration when mapping 
the engine in then is it not best from both emissions and 
indirectly the power point of view to inject right up to the 
point just before the inlet valve closes? 
If you take this event as a permanent set end point and 
build your fuelling up before this event then you have 
the maximum time available for fuelling combined with 
the optimum for the emissions case. 
All the commercial systems i've seen seem to work in 
reverse and fuel from around the ignition event of the 
previous stroke. I think the motive for this comes from 
the case where if load rapidly changes during the time 
between ignition events then this can be accomodated 
by extending the injector on time whereas with the 
fuelling built from the inlet valve closure there may be 
underfuelling until the next injection event. 

Timing Discs:
I've heard the 58X timing disc mentioned here previously 
does this consist of 36 teeth with 2 missing at 180 degree 
seperation to give 58 transitions per revolution?

Martin Evans
100341.377 at compuserve.com