Why use a distributor?

[TurboTR]

It makes sense that it could help the factory setup, because it rapidly runs out of time to adequately charge the ignition coil(s) as rpm rises. A direct way to help address that problem is to raise the coil primary charge voltage from 12v to 16v. This will get more current and energy into the coil primaries in the same limited amount of time since di/dt = V/L. Raise V and di/dt raises as well.

FAST sent us a custom programmed ECU once for a turbo Nissan project. One thing that got messed up in the process was the EST dwell time, since this car was (unexpectedly to FAST) still using the stock inductive ignition rather than a CD ignition. Checking with a scope, the dwell time pulse width wound up being only about 1ms, and the car ran pretty bad generally, and not at all under a load (no surprise). This is exactly analogous to the problem of running out of available dwell time with increasing rpm on the factory setup.

TurboTR