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It would be like saying someone can't put a turbo on their car because they have a 2.73 ratio rear end.
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Right.
I don't see the relevance and wonder what the point being made about the reduction gear happens to be.
Manifold pressure increased but rpm remained the same.
Increasing manifold pressure is the most efficient way of increasing an airplane engines power output.
In the power formula, rpm is divided by 2 so you have to double the rpm for each increase in output.
Of course, you can't realize a very large gain in power without reducing the propeller diameter due to mach losses.
A small increase in manifold pressure of .13 ata realized a 200PS gain in static BHP raising the engine output from 2000 static PS to 2200 static PS at sea level. The power rises slightly (50PS) on the static PS graphs to FTH.
That is static power.
The performance benefits are obvious as noted in the graph Faustnik posted.
One the cooling fins, the BMW 801 series was an air-cooled engine. It does not require oil cooler adjustment as such. Basically air cooled engines operate over a huge range of temperatures when compared to a liquid cooled engine. They are designed that way!!
Liquid cooled engines are much more temperature sensitive and operate over a very narrow range. Water has 25 times the heat absorption capability of air so the engines temperatures remain pretty stable as long as the coolant temperature is within limits. Thus, generally speaking, Liquid cooled engines tend to have longer TBO's than air-cooled engines.
In fact, air cooled engines with oil coolers can suffer from overcooling in the wintertime.
Overcooling is a condition where the oil is not heated up enough to evaporate water and other contaminants from the oil. Overcooling causes internal corrosion which leads to cam spalling and bearing failure.
Lots of air-cooled engines have cowl flaps. The cooling gills on the BMW are just that, cowling flaps. They have nothing in common with radiator inlet controls.
If you read the Flight Manual for the FW-190, except for some specific conditions of flight such as climb in high density altitude conditions, you just leave them closed once the engine is warmed up.
It is not something a pilot would be adjusting constantly like the radiator inlet on a liquid cooled engine.
In general, since water/glycol has a much higher heat capacity than Air, you need a lot of air flow to reduce the temperature a little in a liquid cooled engine.
Read the Operating Notes / Flight Manuals, they will tell you everything.