most electric fans really are not what they are advertized. only two companies that I have ever tested make close to the CFM that they advertize. that is Spal and Tri-Pac. The most CFM is the Spal fan used by Nascar. it flows 2900 CFM of air at 0", or about 2200 cfm at 1.5". which is pitiful as the standard engine fan will push much much more.
to get true fan CFM in your cooling system, you need to know the pressure drop across your radiator core. in most cases, its 1.4" - 1.7" Then you need to get the full fan curves from the vendor and then you can get the actual fan flow for your application. Pusher vs puller almost no difference in performance and I have the dyno runs to prove it.
the key "rules of thumb" for any fan installation are as follows:
Fan IS to be shrouded (this is the biggest improvement to fan efficiency). Did I mention that the fan should be shrouded.
Fan tip to shroud clearance is to be as minimal as can be (to minimize fan re-circulation known as tip loss)
Fan face is to be a minimum of 1/2 the hub diameter of the fan away from the core (this minimizes the useful radiator core blocked by the fan hub)
Your fan is not needed above 25mph, as the velocity of the air from driving exceeds that of the fan.
Fans require horsepower to run.
that being stated. My recommendation is stay with an engine driven fan. if you still overheat, look at the radiator and engine coolant flow.
