A Miller-cycle engine is very similar to an Otto-cycle engine. The Miller-cycle uses pistons, valves, a spark plug, etc., just like an Otto-cycle engine does. There are two big differences:
* A Miller-cycle engine depends on a supercharger.
* A Miller-cycle engine leaves the intake valve open during part of the compression stroke, so that the engine is compressing against the pressure of the supercharger rather than the pressure of the cylinder walls. The effect is increased efficiency, at a level of about 15 percent.
Taken from:
HowStuffWorks "How does a Miller-cycle engine work?"
There are two types of Atkinson Cycle engines, the RA, or Rotary Atkinson, and the PA, or Piston Atkinson. A
true PA engine has a crankshaft that is modified from the Otto Cycle design, as a means to bypass patent restrictions, which often ends up giving the engine an expansion ratio that differs from it's compression (concentration) ratio.
Reference (although not a good one):
Atkinson cycle - Wikipedia, the free encyclopedia
Adding a supercharger to an RA-type Atkinson engine would presumably serve to increase the dynamic compression, but it would not qualify as a Miller Cycle engine, since the Miller Cycle is designed to use a piston which begins the compression stroke against a supercharger's air charge rather than against the cylinder head.