Fans: pushers vs pullers

So are there benefits to pusher fans vs puller fans? I ask because I'm about to upgrade my trans cooler to a larger unit and will be able to fit a 10" fan on the new trans cooler.

For the discussion let's assume were comparing identicle fans with the same CFM rating and both installed in the correct orientation. I should have plenty of room the mount the fan on either side of the cooler.

I would guess that a puller fan has an advantage since it keeps the face of the cooler open to the air forced in by driving. I'd also think since the fan is mounted on the back of the cooler there would be less turbulence of the air exiting the fan and potentially help to add some cooling performance to the radiator?

This is just speculation by me so I'd love to hear if anybody has the facts?
Thanks!!

 

I have no sources to cite but I've always heard that this up here ^^ is really the only reason, space not being an issue.

 

Awesome, thanks for the reply! I'm definatly leaning towards doing like this as of right now.

 

Agreed. A pusher should really only be used if you're tight on space. They do work fine, I run one on my swapped E30. However if I had the clearance than I'd be using a puller / mechanical fan.

 

Actually a pusher configuration is technically more efficient. The air density is greater on the inlet side of the cooler since the air temp is lower resulting in greeater efficiency from the fan and reduced fan motor temperature. You ideally would also space the fan an inch or so away from the cooler core and shroud it to better distribute the air across the entire face instead of just the area under the fan and pressurize the cavity between the shroud and core face.

 

To maximize the effectiveness of a fan you need a shroud, that directs all airflow though the fan. If you were to do this on the front side of the radiator, you would block a significant portion off from natural cruising airflow, causing significant inefficiancy. If you didn't use a shroud on the front, you would effectively reduce the fans effectiveness to only the fins in front of the fan, causing significant inefficiency as this is likely less than 1/2 the radiator. By running a fan on the back with a shroud, no fins are blocked from cruising airflow providing excellent effeciancy, while also directing 100% coverage of radiator fins to have air pulled through when the fan runs also causing excellent efficiency. There is a reason why every auto manufacture puts them on the back.

 

Absolutely, great points crashnburn. If the installation allows for direct airflow then a puller configuration would make more sense to make the most of natural cooling through the core. If there is not direct "ram" air due to the installation or slow vehicle speeds then pusher would more efficient. It all depends on the application and installation.

 

Thanks for all the replies! It's really appreciated. I'm looking at hayden cooler that's about 11"X11" I made a cardboard mockup and shouldn't have any issues getting a fan in the puller orientation.

So could a puller fan mounted on the trans cooler also improve radiator efficiency since it's pushing more air over the radiator in tandem with the oem mechanical fan?

 

You're not wanting to put a puller fan at the front? That's how I'm understanding you based on your question to put a puller fan on the trans cooler, which will go where the cardboard is. If you put the fan there, they want to configure the fan to pushing mode. In pulling mode, the fan goes on the same side as the OEM fan.

 

I'm talking about putting a puller behind the trans cooler (in between the the radiator and new "cardboard" cooler). The fan will be affixed to the new cooler. Overall airflow would be pulled through the cooler toward the engine and on through the oem mechanical fan.
My explanation is probably convoluted but the new cooler will be mounted similar to the small OEM transcooler on the core support and not directly to the AC condenser. There is plenty of room there.

 

A puller fan is preferred in most applications where the cooler will get airflow with vehicle movement. This is because during movement, air will be able to access the full face of the cooler. If there is a pusher fan infront of the cooler, the fan itself will actually reduce airflow during movement and if the fan is very close to the cooler, the blades could possibly flex and contact the fins.
In instances where there is limited space between the radiator and engine, a pusher is better than nothing.

 

Gotcha. That certainly is an option if fitting the electric fan on the engines side is not viable. With a trans cooler that large, have you considered bypassing the trans cooling lines to the radiator? That will keep your engine running cooler and negates the possibility of coolant-ATF cross contamination should the radiator ever rupture.

 

Yes bypassing has crossed my mind but I'm gonna hold off for now and even run that big ass cooler in series with the oem equipment. It's only a year old truck so if I have issues it's allot easier to plum the stock cooler back in and drop the busted truck off at the dealer for warranty lol. The hayden cooler has a viscosity bypass so I'm not too worried about over cooling.

To be honest I haven't had any issues with the stock cooling setup but the 120 bucks in parts to run a larger cooler and fan will give me a little comfort the next time I'm in 4x4 pulling that camper through the sand/mud getting to the campsites away from the amateurs

 

You're right; don't do any major changes while under warranty.