Well, now you're getting a bit off topic, but I'll toss a couple of considerations out on air as it relates to engines. I'm guessing you know pretty much all that follows, but somebody may pick up something of interest.
When you compress air, the temperature of the air increases. An intercooler merely cools that "heat of compression", thus increasing its density. Higher density means more mass per volume. Since combustion relies on a chemical reaction between fuel and air, more mass means more combustion/power.
A piston also compresses the vapor in the cylinder. In a normal engine, the air enters the cylinder under atmospheric pressure. Add a turbocharger and more air will enter, as the air is compressed to higher than atmospheric pressure. Add an intercooler and even more air mass will enter the cylinder. The turbo and intercooler affect the overall compression ratio by feeding the cylinder air of a higher density than ambient atmospheric air.
Some folks not knowing any better will add a turbo (with or without intercooler) to their engine to develop more power. One problem is that this changes the engine's overall compression ratio and the compression of the turbo gets multiplied by the compression of the piston. As you've noted, this can create pre-ignition and places a heckuva lot more stress on the engine components. Hence the need to beef up crank components and often increase the combustion volume (shorter stroke, etc.).
Anyway, the intercooler works because the "hot" air it sees has been compressed by a turbocharger and it can use ambient air to cool it. The analogy with water cooling is to have sufficient radiator area and air flow to cool the fluid as close to ambient as possible. Locating the radiator immediately ahead of the block theoretically gives the coolest possible fluid to the chip, but often this is not how things really pan out. The real key is providing the coolest air possible to the radiator and keeping the fluid runs reasonably straight and short. Putting the radiator right ahead of the chip is no good if that means passing warm case air over it.
It isn't quite the same as an intercooler, either, as at any reasonable flow rate the temperature of fluid in the loop just doesn't change much. At 50 gph, water can absorb over 150 watts with less than 1°C temperature rise. Changes like that are quite small compared to the delta_T you'll often find between ambient air and the air inside a case.
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