Injector Sizing: REALLY dumb question

[goflo at pacbell.net]

Well, let's see if I've got it straight...
Each TBI injector feeds four cylinders (in a V-8) whereas one injector
per cyl in TPI, so it seems reasonable that the TPI injector is about
1/4 the capacity of the TBI injector. 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. This means the
orifice in the injector must be of a size to meter the right amount
of fuel for idle/off-idle conditions with a inj pulse of 1-2
milliseconds. This orifice size, unfortunately, is not adequate for
best power at speed, so you end up compromising per application. Or
adding auxiliary injectors :) 

Regards, Jack

Mike Turner wrote:
> 
> In several very recent threads, it has been stated that drivability
> problems (usually at idle IIRC) preclude the use of large injectors for
> TPI. Yet, TBI uses one or two large injectors with generally no mention of
> such problems. Would someone please tell a dumb sparky exactly what is
> causing problems with high flow injectors in TPI and why that is not a
> problem with TBI? Back to lurking in the shadows......with my 332
> controlled and fully instrumented CSH low over my eyes and hopefully ready
> for the impending  walls of flame.