Not Towing? Go electric.
This question is all that matters for the folks towing: You have heard the mechanical fan engage at freeway speed while towing? Perhaps on a long uphill mountain pull where you are almost to the top going flat out 15MPH under the speed limit and the dreaded fan locks up and slows you down more?
Zubes may comment on this:
What is the CFM of a mechanical fan? It is over 5000 CFM at engine speed where the most heat is generated.
The CFM of e-fans is known and constant. Less than 5000CFM
Look at the blade angle of that 19" mechanical fan. Think of it turning at 3000 RPM. It will move more air than the electric fan. (GM likes to run this TBSS hot. The computer commands our fan at 74% of engine speed at 236 coolant degrees. 225 is 29% and 210 is 7%, zero fan below this temp.)
2 square feet of radiator surface will have 10560 CFM flowing over it at 60MPH minus the restriction of: the grille (Intentional to slow the air down) and the two radiators it has to go through. To do any good the mechanical fan has to exceed the ram airflow through the radiator. Otherwise it can slow down the airflow. The noisy fan is pulling way over 10560 CFM at 60MPH!
Pulling a long hill even at speed stuff heats up fast! This is the only area that the mechanical fan will open a can of whoop butt on it's electric replacement - At road speed where the CFM of an electric is under the road speed airflow.
Not all is lost. Alvin at PCM for less can tweak your factory tune to command more fan % for the mechanical diehards. This will help the AC and engine temperature with the above GM light fan use. (The trans cooler he sells is also highly recommended for towing.)
Now you have information to decide how hard you will run your TBSS while towing for fan choices. Are you that 1%?
Oh yes, This is what I tow around.