Yes UberRoo,
The deeper you go, the more involved it gets. Thats whats kept me involved in the learning process, of Auto Engineering for so long.
I think to define "supercharge" as a particular object, is a bit narrow. I think it is an action, more than a object. All the units that you mention, would have to be pumps driven by the engine. regardless if driven by mechanics, exhaust gas, electrically or a seperate piston. They are all aimed at getting a higher concertration of air/fuel into the combustion chamber, to increase the amount of gas and heat, to give a gain in pressure on the piston.
There are other ways of achiving this, In gas and fuels, that don't have to be bolted on. These must also be classed as super charging the engine. But we have the popular term, "Supercharger", and everybodys mind sees a 6-71 GM blower on a bent 8.
On the two stroke, the opposed ports that you speak about, are a bit out dated, I know they still have favour in US outboards, but thats the US. Out in the real world, they gave way to the Schneurle system of twin transfer ports, one on each side of the barrel. This got away from the defector lump on the piston that hindered power.
The crankcase compression is only in theory, It does not pressurise the cylinder, as the exhaust port is still open, after the transfer ports have closed. The big gain, was when the piston ported inlet, gave way to rotary and reed inlet systems. This allowed the exhaust, transfer and inlet to all be open at the same time. This allowed the exhaust action to, 1. Remove the spent gas, 2. Pull fresh gas up from the crankcase, 3. Pull new gas in the inlet to continue the filling. This not only filled the cylinder but also filled the exhaust header pipe with fresh gas. The last action of the exhaust was 4. To then push this gas back into the cylinder as the exhaust port closed.
This is where the stroker gets is huge volumetric effecience from. Is this Supercharing the cylinder? It certinly forces more charge in than the swept volume of the cylinder.
Good topic.
Harvey.
Oh, ps, GM strokers use four exhaust valves in the head, ring inlet ports at the bottom of the cylinder.