What difference will I notice when I turn on my magical gadget and take the injected water back out before it enters the engine?
More air going into the cylinders that was displaced by the water. What you're describing is exactly what the intercooler does, remove heat from the charge air.
So what does water injection ever do more than a good air to water IC in the first place?
Two things.
The methanol commonly mixed in is an additional fuel to be burned = more power.
Water "steam cleans" the cylinder of carbon. Reducing hot spots, friction and ring plugging. The "steam engine" effect so often claimed is absolutely
false. The additional pressure from the steam expansion is extremely small compared to the combustion of the fuel.
The "1600x expansion" so often cited for steam is
in the open atmosphere. Combustion chamber pressure is extremely high, upwards of
700psi.
every point of compression is worth about 40hp in our 12v's.. it puts flame out thats why the temps go down..
Wrong on both counts.
Static compression is what raises power. That is the expansion ratio between chamber volume at TDC and BDC. Dynamic compression, such as boost and WI, has no effect on power or efficiency. Its the extra oxygen that does that.
WI doesn't put the flame out, it lowers the combustion temperature. If it puts the flame out you get a severe reduction in power and high exhaust smoke from the leftover unburned fuel.