CFM airflow and the lies we are sold…

Everyone today seems to want to move to electric fans.  Fan clutches are a dying technology in the eyes of the masses… just bolt on some electric fan that magically pushes 4,000 CFM and your engine will stay cool.


A 20 inch fan blade mounted to an engine via a fan clutch will push more air than an electric turd could think of.  Don’t get me wrong I am a fan of electric fans, but sooo often you get these car *experts* who think they can slap a fan on there and magically the engine will run better and they will increase their MPGs.

First off – most universal electric fan suppliers claims are a joke.  3,000 CFM is the measurement taken when there is nothing in front of the fan.  Really??  How does a fan with nothing in front of it cool a radiator or condenser?  Then add in a transmission cooler, or some other heat-exchanger to pull air through and suddenly that fan barely cools anything.  Even with a shroud (more on this later) an electric fan will struggle to keep anything over 244cid cool (4 liters for you import fans).  Perfect example – my buddy has a 90s Fox body Mustang with a 5-point-slow with a few bolt on goodies (nothing extreme, no nitrous or FI).  We installed a Proform shroud/fan combo made for his EXACT setup.  Driving around town – couldn’t stay cool.  He then bought what all the forums recommend – a higher performing fan Flex-a-Lite / Black Magic turd or something to that effect.  Again, same results… couldn’t keep it cool.  Yes he lives in Dallas, TX so the summers are on the warm side but its not like this is Arizona or New Mexico or something… this is on a sub 100°F day and still breaking 225°F on the gauge.  This was a new aftermarket gauge and sensor – they were dead on when checked with my IR laser heat gun.

Long story short – I laughed and told him a fan clutch would have been maybe $35.  How much did 2 different electric fan setups cost?  He saved on labor since he’s a buddy of mine (minus the beers!), but a shop would have taken him for a ride worse than our current members of congress.  The difference would have paid for the 0.5 MPG increase from the electric fans for another 2-3 years.

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