“But the mixture doesn't escape at its operating rpm, The converse occurs when the considerable overspill into the exhaust is returned and a 2bar pressure maintained at the exhaust port as it is closed. Thus, its power potential far exceeds what is possible with a mechanically closing valve.
As I said previously, context is everything.”
In all engines there is involved “a mechanically closing valve” that actually traps the fresh charge into the cylinder before the compression.
In the conventional 2-strokes this valve is the piston closing the exhaust port.
In the 4-stroke engines this valve is the intake poppet valve.
In the PatATE 2-stroke this valve is the piston closing the hybrid/transfer port.
The specific torque provided by the 4-stroke Ducati Panigale Desmo (which is based on a pure mechanical control over its poppet valves, without VVT / phaser) exceeds by far the half of the specific torque of any 2-stroke.
In the following plot it is shown the torque of the 1299 and 1199 Ducati Panigale:
The specific torque is 110mN/lt.
The flat torque curve (from 8,000 to 10,500 rpm) is one more characteristic not met in the 2-strokes.
The exhaust helps the induction of the fresh charge into the cylinder of the Panigale only during the overlap of the intake and exhaust valves.
After the overlap, everything is rely exclusively on the intake system.
And judging from the torque provided, the intake system makes an excellent “job”.
As the tuned exhaust of the conventional 2-stroke over-boosts the cylinder (provided the engine is running “at its operating rpm” (tuned?), as you write), similarly the intake system over-boosts the cylinder of the 4-stroke.
And despite the increased mechanical friction of the 4-stroke (one power stroke per two crankshaft rotations), it provides more energy per power stroke than a similar 2-stroke.
Now take the case of the PatATE.
The compression starts when the piston closes the hybrid / transfer port. A properly designed intake system can over-boost the cylinder in a way similar to that of the Panigale.
In such a case the exhaust plays a secondary role: it helps (as the exhaust of the Panigale 4-stroke); however the dominant role belongs to the induction system (as in the Panigale 4-stroke).
Contrary to the conventional 2-strokes, the PatATE needs not to be based on a tuned exhaust (Kaaden).
However its characteristically faster exhaust opening (faster in comparison to the conventional 2-stroke engines) causes a faster blow-down which is crucial at higher revs.
The PatATE seems to combine the characteristics of the 2-strokes (like: one power stroke per crankshaft rotation, simplicity, lightweight, high specific power, low cost, etc) with the characteristics of the 4-strokes (like: better lubrication and lower lube specific consumption, uniform temperature of the cylinder liner and of the piston skirt, scuffing reliability, earlier closing of the exhaust, compliance to emission regulations, better fuel efficiency etc) and with some special characteristic of its own, like the absence of red hot temperatures on the exhaust port or exhaust valve, etc.