<< What do you mean by over boosting? Sounds like a prescription for
detonation.
 As opposed to pre ignition. Two different things. Lets define detonation
 as an extremely rapid burning of the fuel and pre ignition as the premature
 ignition of the fuel relative to TDC.
 Paul Lamar

Detonation is the spontaneous ignition of a fuel air mixture after the spark
event, but at a location remote from the spark plugs. Generally a function of
chamber temperature and may be specific to mixture temperature, plus the heat
of compression, poor homogenization of the mixture, a component or components
over temperature, such as a plug electrode, higher than normal burn rate, the
edge of a poorly fitted head gasket, (in piston engines). or a glowing carbon
deposit.

In any case detonation depends on an overheated (fill in the blank) to raise
the temperature of the mixture to a point that ignition occurs that is not
associated with the spark plug(s) but occurs after the plug(s) fire.

If there is only air available up to the timing event (in the pretend engine)
there can be no detonation. 

I don't agree with that. You just said detonation can occur after the plugs fire.

Suppose we start injection at 22 degree BTDC and
the spark event is at 20 degrees BTDC. The engines are tolerant of a wide
range of timing, a computer controlled curve could be developed if required. You
can tailor the delivery to start and be finished between 22 degrees and zero
degrees, or at 26 degrees with the spark at 22 degrees, or anything else just by
moving the fuel cam and, or, changing it's profile. I am thinking that once
up to operating temperature, there would be little mixture for the plugs to
light. Particularly if there were a turbo in use. The fuel would be burning just
off the tip of the injector. And that location being the only fuel available,
there could be no detonation.  You can also control the burn rate with the cam
profile.

Lynn E. Hanover

Detonation is characterized by a rapid increase in pressure. Pre ignition
not necessarily so. Direct fuel injection does not preclude detonation.

Paul Lamar

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