Genghis, I'm almost embarrased to ask this, because I should know - could you please describe the "coolant-loop type carb heat you see on a lot of the newer Rotax 912 / 914 installations"? My Rotax 914 doesn't have a carb heat control, and I was led to believe that this was because the inlet air is routed around the turbo-chargers which warm the air sufficiently to avoid carb ice. Is there actually more to it than this?
CBLong, the coolant-loop you're thinking of isn't carb heat - it heats the mixture after it leaves the carb. I believe its purpose is to prevent the condensation of the fuel on the inlet manifolds - the fuel needs to be in a vapourised state when it reaches the cylinders, not a liquid state. But I agree - my Spitfire 1500 doesn't seem to suffer from any carb ice problems. There is very little room under the Spitfire bonnet, though, so I suspect that the air is fairly well warmed by the general engine heat.
On a more general note, I have often thought that part of the reason carb ice is more of a problem in aircraft than cars is because it mainly occurs at low power settings but high speeds - a situation which cars don't often find themselves in. Is there any truth in my theory?
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