Changing injector pulse rate at idle?

[Craig Pugsley]

> I previously explained
> > > 
> > > This is exactly the technique that we have resorted to for high flow
> > > rotary applications.  The injectors found on factory Mazda 13B efi
> > > motors are huge - they flow 2-3 times the volume of 'normal' injectors.
> 
>  and Craig asked :
> 
> > Is the idea to have injectors of the same size, or a small & a big one?
> > 
> 
> I can't remember how Mazda do it for the six port 13B turbo.  I would
> guess that the primary injector would be the smaller of the two if they 
> were in fact different.

A few trivial bits of info:
13B SIV (=2nd gen RX7) motors, from mazda training manuals:
Non turbo
Pri & sec injectors: 459cc/min @ 36psi regulator pressure
Fuel pump outlet pressure: 64 - 85 PSI acceptable range

Turbo
Pri & sec injectors: ~550cc/min @ 36psi regulator pressure
Fuel pump outlet pressure: 71 - 92 PSI acceptable range

12A turbo (1st gen RX7 / SIII Japan model) and the GSL-SE (13B 6 port
SIII RX7 US model) both only had 1 injector per rotor (I _think_).

According to the Jeff Hartman book (previously mentioned by me), the
GSL-SE injector is the highest flowing injector used on a production car
(obviously there's race injectors that flow more)

> Mazda uses an interesting system where the primary injector does all
> of the work until it reaches 10 mS pulsewidth.  After this point the 
> primary switches to something like 5 mS and the same for the secondaries.
> As far as I know, the transition is undetectable.
> 
> Our system allows the user to adjust a 'stage factor' which is the
> ratio of opening time between secondary and primary injector outputs
> expressed as a percentage.  Since the system is purely empirical, any

Re the stage % factor, does this mean that the secondary injector will
always be at, say, 50% of the primary. Does the secondary injector get
switch off below a certain pulse width or is it always enabled. (EG if
the primary is at 1ms - say at idle, will the secondary be at 0.5ms - in
the 'non-linear/predicatble' region??)

Also, do you know if the SIV ignition system is suitable for high output
motors. (ie 1 coil for each trailing plug, and a shared coil for the two
leadings)- A certain mazda workshop in the North of Melbourne claims
that it (quote) 'Wont work on high output turbo or peripheral port
motors' due to the spark overlap in the leadings occurring too close to
the apex seal as it's on the way past.
OTOH, maybe they're full of s**t!!

Cheers,
Craig.