A/C piston v Auto piston
Hi Gargleblaster
As I understand the reason for the big difference in cubic capacity in auto and aeros is that the prop' rpm is restricted because if it was to Max rpm the same as an auto engine at @ 6000 rpm the tips of the prop blades would be supersonic which would not work. So the prop pitch is designed to operate in a rpm band half that of an auto engine approx. so we need to be able to produce the power required at approx half auto rpm so hence the much bigger cubic capacity.
Your question on carb ice is a good one. I used to drive an old volvo 340 (uk) with a renault engine and it used to lose power on a long run if I was giving it wigins (relative term for a 340).One day I eventually saw the evidence. I had been driving the car with the air cleaner removed although i can,t remember why. when the car stopped i got out and looked under the bonnet into the carb and i could see this thing like a large polo mint. the car was not running and very shorty the polo mint came off the carb wall and shorly fell apart and dissappeared.Easier to believe when you have seen it!