Originally Posted by rv7charlie
Are those constant velocity carbs? I wonder how they react to a pressure recovery air feed (common on Lyc powered RVs, etc). Just speculation, but that might be why they are fed from 'ambient' air in the cowl.
Apparently it works fine as long as the carb. vent tubes are at the same air pressure as the inlet of the carb.
That is why the carb vent hoses are connected to the induction airbox on the turbocharged 914 or when the optional Rotax induction airbox is used on the 912.
I have mentioned previously....... during the development of the RV-12, testing was done with an airbox fed by outside air. The performance difference was determined to be small enough that it didn't justify the cost and complexity of making that part of the design