Paul,
I guess it's been mentioned before, but I just can't get my head around the
constant flow mechanical system from Airflow Performance.
Can it be explained simply as I feel any low pressure fuel injection that
performs flawlessly, should be the method of choice.
George (down under)

It is not exactly low pressure.
Well I am not sure how it works exactly. A positive displacement fuel pump mechanically driven by the engine probably  supplies fuel proportional to engine RPM. Steve mentioned a venturi. The venturi sends a signal proportional to air flow and that signal controls the fuel flow through a valve controlled by a diaphragm. That sends the fuel to a  spider that divides it into each individual runner nozzle. The nozzle hole sizes are adjusted to even out the EGT for each cylinder. Probably very similar to the mechanical Bendix system that has been around for 60 or more years. There is no real need for timed injection. Most timed injectors are flat out anyway at RPM's of 6000 and above. Aircraft engines don't need EFI. The engine is manually leaned by the pilot according to the EGT.

Paul Lamar

Paul,
I'm wondering if  the fuel could be controlled by pressure. I understand you
to say the metering is controlled by mechanical means (RPM) - that sounds
good. The quicker the engine goes the faster the pump runs, but wouldn't
variable pressure be also a good system or is variable pressure too hard to
do and is that why injectors are timed.
George ( down under)

I guess you could call it variable pressure.

Injectors are timed at low RPM/low power for minimizing   fuel burn and
low emissions. Exactly were car engines spend 90% of the time.

Paul Lamar