What I mean to say is, which method provides more efficient cooling???
Pulling air through the radiator?
Or
Pushing air through the radiator???
Trying to maximize the effectiveness of my electric fan… Any info is great!!!
Thanks in advance!!!!!

 

6 of one, half a dozen of the other.

The important thing is that the fan have a proper shroud.

 

it would be harder to mount a pushing fan with a decent shroud, so I would probably say pulling is better just because it's easier to do effectively.

 

It would be virtually impossible to shroud it properly in a pushing application while simultaneously exposing as much as possible of the frontal area of the radiator to the incoming airflow through the front duct.

 

Pulling, for 3 reasons.

1. Axial fans are better at pulling (negative pressure) especially since the radiator surface is close. Most recommendations for pushing (positive pressure) include uprating the fan by 25% and/or allowing for 2-1/2 fan diameters to the heat exchanger surface. The air leaves an axial fan with lots of rotational energy and turbulence. The purpose for the extra distance is to allow the turbulence to subside and therefore permit the air to flow uniformly through the heat exchanger.
   
   
2. Airflow is caused by pressure differentials. Pressure differentials are additive.
   
   Let's assume your fan and shroud together covers 100% of the radiator surface. The fan accounts for 50% and the shroud accounts for 50% of the radiator surface.
   
   If you are idling parked and also assuming the parameters are met from Reason 1 then the puller and the pusher perform the same.
   
   Ram air effect: Now drive at 35MPH. The pressure that builds up in front of the radiator (the ram air effect) is applied to 100% of the radiator surface on the puller. The pressure is only applied to 50% of the surface on the pusher. 100% >50%.
   
   
3. Now, think about A/C condensers and FMIC's and the physical relationships and spaces available up front. You see there is not a lot of reason to consider the pusher as a primary cooling fan.

Pusher fans are generally relegated to auxiliary use.


Class Dismissed.

 

I agree with you overall, but point 2 doesn't really make any sense, unless you're just saying you're cutting down on the airflow to the radiator.

Also, a minor debate point for fun: Heat transfer is more efficient at lower pressures (so maybe the shroud could help). Hence that's why the surface area of the radiator is greater than the surface area of the air inlet at the bumper. Please don't ask me to prove it because that would make me spend too much time looking through my old college textbooks instead of ripping down popcorn ceilings.

 

Thank you for the answer(s)!!!!
It seems to be that the current way I have my electric fan and shroud set up would be the most efficent that I can manage. Excellent. Thanks for the input
DallasFC1

 

I'm telling you WHY the airflow is cut down to the rad on a pusher.

And taking that debate point to it's illogical extreme why not cover the entire front of the radiator and lower the pressure even more for even better heat transfer?

p.s. I really don't want to know your answer because you would have to look up those dusty old books, so get back to those ceilings!

Happy New Year!

 

As long as the fan is functioning properly and moving enough air by itself to cool effectively then it'll work either way - mine is behind the rad though for many reasons as mentioned, but in some cases if it were totally necessary I'd do it, but then and only then.

Also keep in mind the flow through the entire bay itself. Lots of air moving in with no air moving out means little overall flow through the bay...pressure differential is a pretty major thing in the cooling equation.

 

Pulling is better. It is a fact, not a debate.

Also, a moving fan restricts airflow at higher vehicle speeds, so use a thermostat to activate the fan so it will shut off when not needed.

 

This is certainly a well documented fact in computer watercooled systems, so I'd assume it holds true in our case as well.

 

imo good question

 

Run both. I'm not kidding.

 

Both is probably not a good idea either, IMHO i would say that a fan in the path of air at highway speeds would slow the air down as it entered the rad reducing cooling at higher speeds

also have you ever seen all the dents and crap in the front of a radiator, what do you think a rock flying out from under a semi on the highway is going to do to a plasitc fan..

I could personally vouch that rocks caught between the fan and the rad is BAD...
See when I was younger I thought it would be cool to do some do-nuts in the gravel lot behind my friends place, in a front wheel drive car that means reverse, so rocks flew up in my engine bay and got stuck between the rad and fan, well after about 2 days banging around in there they poped a hole in my rad broke the fan shroud as well as breaking a fan blade... No I didn't hear any of this banging because my young dumb self never drove with the radio off or turned down the slightest.