Two fans, and both wired to run at same time. The object of the fan is to cool down a warmer engine, so IMHO fan noise is a minor issue. Be sure you wire things so that the air blows toward the block, paper towel sucked toward grille rather than blown away. My PO reversed the wiring when he spliced in salvage yard fans, makes you overheat at idle.

 

Yes, the correct air flow is rather paramount to this type ofupgrade , i knew I forgot something.