I have a Devillbis compressor that the pump bit the dust years ago. It is a 6 hp 60 gallon. I have been keeping it around only to keep reserve air in. I just got a free Quincy 3.5hp 20 gallon compressor with a rusted out tank(runs perfect). Last night I decide to put the pump/motor from the Quincy onto the 60 gallon tank. Everything is hooked up and works perfect(whisper quite ). Now here is the question: the quincy originally did 6.5cfm@90psi with the 20 gallon tank. What if any cfms did I add by upping my tank to 60 gallons?

 

the CFM stays the same. the compressor is what determines the cfm, not the tank. the tank only determine the amount of available air to use before the compressor turns back on.