The R-1830 used in the F4F and FM-1 used an intercooler, as did the R-2800 used in the F4F, F6F and P-61A/B. This led to the F4F/FM-1 having externally mounted oil coolers, since the cowling was taken up by scoops for the intercooler and the F4U having air intakes in the wing root.Intercooler is installed only when there is either an external supercharger or a turbocharger.
The two stage supercharged V-1650 and other similar Merlins were both aftercooled and intercooled, because the internal routing of the coolant was designed to pick up some of the heat between the supercharger stages before reaching the main source of charge cooling, the aftercooler.
Yes, but it does have an "Interstage Water Cooling passage", so it was intended for that purpose. Obviously, there is more Delta T at the aftercooler point, which is another example of brilliant design. Today's turbocharged aircraft engines only seem to have have aftercoolers, although they call them "intercoolers." I suppose that liquid aftercoolers could have been used on single stage supercharging in WWII but it seems that was not done by anyone.True. But it is not strictly speaking an "inter" cooler in the sense that the two-stages supercharger is monobloc