which is more efficent, push or pull type thermo fan setup??

[- THOR -]

Hey guys,

I have a JZA70 1JZ and my water pump is leaking. I am about to swap it to a 2JZ-GTE non hydrolic water pump. Due to the change in pumps, I will need to scrap the Hydro fan setup and get myself some thermos.

The Car will be a drift car, and I am wondering which will be more efficient.... A pull type setup with the appropriate shroud or a push type setup???

The reason I ask is because I would much prefer the room in the engine bay and go for a Push type setup, but if the the Pull type setup with a shroud is better then I will just have to go with that!

Please help me out

Thor.

[river]

Hi,

A shroud increases the cooling efficiency of the system. You need the fan operating when stationary or at low speeds. An unshrouded fan is moving air only through the portion of the radiator equal to the surface area of the fan. Shrouding your radiator lets the fan pull air through the entire core.

I don't know if there is much difference between push vs pull on the fans, but I am not sure if a shroud on a push fan would work as well as a shroud does on a pull type set-up.

Also, at higher speeds, when the fan is not required, I think the push type fan would offer more obstruction to air trying to get into the radiator, as opposed to a pull type.

Most people seem to go for the push type due to space restrictions, other wise the pull type with shroud is the preferred method. Well, it is for me.

seeyuzz
river

[Billzilla]

Pull is more efficient.

[RA35GT]

SPAL rate their 14" fan at a higher cfm when mounted as pull instead of push.

Puller fan set up with shroud is the way to go I reckon.

PS. Don't run a shroud with a push setup, its of no great benefit and also blocks the core when driving.

[Admiral coFF33]

pull type with shroud

[- THOR -]

yeah I was definitely not going to use a shroud if i went the push type route
... this all sucks, i was hoping that a push setup would be as efficient so my engine bay had more room and looked neater.... *sigh* ahh well. I will just have to live with it lol!

The funny thing is I actually already have a pretty sweet pull setup which utilises two 12inch fans with a shroud that is spaced back 2inchs (which is even better!!), but the only problem is it won't fit with my new cooler piping . I used to run this setup on my last engine combo and it was great!

Thanks for all the input guys, really appreciate it! if anybody has hookups to cheap fans and shrouds, let me know!

Thor.

[RA35GT]

cant go wrong with au falcon twin thermos.

if no room, get some spal fans and make a shroud. easy as man.

[omp]

I have heard AU falcon thermo's are pretty good. What is it that makes them good? Is it that they are plentiful? The thermo's and shroud are easy to fit to other radiators? Or they are just generally a good design?

[RA35GT]

they move some decent air and come in a shroud already. which is easy to modify to suit most cars.

(wasnt just the au, so you could get it from an el onwards or something which had the twin thermos in a shroud)

[matty12]

they started on the ef but the au's are a little more compact but are also slightly thicker.But both of they are failry big anyways,otherwise have a gander at modeos,same idea but smaller,they fit most things far better than the au's(kingers/commodores/skylines/silvias etc).

I may be able to get you spals/modeos/au's for a reasonable price if you need.

[Z2TT]

A Pull type is better.

because fans sucking air from behind the radiator are making a positive draught from the front to back, all the way through. A fan on the front of the radiator by itself, if not assisted by one from the back, cannot work efficiently. It can only blow through a specific area of the radiator equal to the diameter of the fan blade itself, and the small amount of air that does pass through that area will deflect sideways when it hits the surface of your radiator, where as a pull type setup allows air to be sucked through the exchanger and blown again away from the radiator, also incoming air at higher speeds will still be able to provide good cooling without obstruction. You should have enough room on the JZA70 to fit some AU Thermos on the back without too much problem.

[- THOR -]

kool, i very much understand what pull and push fans do. I now also know for a fact that pull fans with shroud are the best.

Z2TT: there is no way au falcon thermos will fit man. if you have a look at even stock a70 intercooler piping, then you will know what i mean!!

at this point the only pull fan with a shroud setup i see working is if i utilised the stock hydro fan shroud, and put my own 16' thermo in there, otherwise it is 2 Push 12' thermos for me!

[oldcorollas]

enough babbling
A pull fan is approx 15% more efficient.
This is simply due to the pressure drop across the fan blades.
A puller can maintain a higher pressure decrease, whereas a pusher cannot maintain as high a pressure increase.

you can shroud both push and pull. look at an audi (80-100?) pull shroud, with the flaps to allow air to escape if fan is not keeping up with incoming air.

[Billzilla]

enough babbling
A pull fan is approx 15% more efficient.
This is simply due to the pressure drop across the fan blades.
A puller can maintain a higher pressure decrease, whereas a pusher cannot maintain as high a pressure increase.

you can shroud both push and pull. look at an audi (80-100?) pull shroud, with the flaps to allow air to escape if fan is not keeping up with incoming air.

They look like this?





Interesting post, I knew pull was more efficient, but not by 15%.

[PlacentaJuan]

i woudl have thought a pull fan was better because that actual fan assembly itself would be a restriction if it was in front of the radiator and in the airflow.