IO360 parallel valve
RV7 Inlet (SJ) 2-7/8" ID Your air filter can lose quite a bit if too small.
Drag is not that the air slows down in transit, but the inefficiency of the drag internally. Then the low pressure at the exit vs inlet. Low pressure times area is drag. Pressure makes velocity, so either are good. (as SCSMITH is teaching me to calculate) The exit loss should be considered as a separate issue.
DanH has shown that a "large" (large relative to the exit) air inlet is not bad if the flow and exit conditions are tightly controlled (i.e. mass flow)
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