Elec fans

[Guts]

Which would you do?

1 big fan (13 inch) with a CFM of 1430 and the cowl. This would be pulling the air through the radiator.

Or 2 smaller fans (10 inch) with a CFM of 650 each and no cowl as the 2 smaller fans cover most of the radiator anyway. This would be pushing the air through the radiator.

 

[mycarhasposessedme]

Pushing the air through the radiator doesn't work very well for eg: I had twin Davies Craig thermo's on a project of mine in a suck through configuration and they worked unreal. (very worked N/A V8)
One day I wondered how they would go in a blow through setup, so I reversed the polarity on them and changed nothing else.
Now the engine could not even get cool enough to switch the fans off. So with it sitting there idling it would just get hotter and hotter with the fans going flat out, the loss of efiency is that great.

 

[Guts]

If you didn`t put the fans on the out side to push the air through you were pushing hot air off the motor through the radiator instead of pushing cool air from outside the engine bay area in.

 

[autocol]

even so... every time i've heard of blow through set-ups, all i've heard is that they were a pain in the arse...

 

[mycarhasposessedme]

When I tested the blow through setup the bonnet was open and the car idling up from cold.
To me this points to ineffiency of the blow through setup rather than simply hot air being pushed back into the radiator, also quite a gap between the engine and radiator.

 

[Lextreme II]

I have 2 16" electric fans installed in my Celsior/LS400 http://www.lextreme.com/fan.htm

 

[400ZED]

reversing the polarity will give a dam inefficent fan the blades are designed to spin one way spinning them the other way would probably half their efficence just becase they were not designed as push fans i don't think that is a very fair experiment.
You can't argue that push fans are great for engine bay space.

 

[Lextreme II]

I think electric fan/s that are pushed are slightly ineffecient because its blocking some incoming cold air. Pulling fans are install behind the radiator. That is from a mechanic advantage point of view. I am sure there are electrical advantage due to polarity mounting it behind the radiator.

 

[Toranamat69]

Most aftermarket cooling fans I have seen, you can remove the blades them and reverse the polarity of the motor if you are mounting on the front.
At least the blades are going the right way then.
Not sure about comparative efficiency of front or rear mount- I have used both successfully but I tend to go for the big overkill.

 

[400ZED]

At least the blades are going the right way then.
QUOTE]

I agree with this if you were parked and just reversed polarity you had bldes spinning the wrong way and they would be worribley inefficent. you would be able to cool your car with a push setup.


Question.
has anyone tried swaping the blades around on a hydralic fan and turning it into a push fan?

Talking to the guy that made my radiator he said they are the best fan he has ever delt with even with the power drain i think they rock. as i might be doing some burnouts along the line i am very happy to keep mine but might need some more room one dan and need to trun it into a push fan.

 

[mycarhasposessedme]

Ok,ok I agree my test was floored. I should have reversed the blades also.
I actually still have the thermos in the garage, so i went down and pulled them out.
Even though they are a very basic fan design ie:5 short straight blades with a pitch of 45 deg, they do have a slight curve in each blade. I should have spotted that. = test void.
Appologies

 

[Toranamat69]

Got my words a bit mixed up above but it looks like everyone understood what I meant.

Just another note on the original query of the thread - it is a good idea to checkout what they call the droop curves for the cooling fans as the airflow can change quite dramatically if the fans are blowing through lots of coolers as there is a large pressure drop.
My poor fans have to get the air through and oil cooler, an aircon condenser then a 5 row radiator so there is a large pressure drop there.
Generally speaking larger single fans will deal with a high pressure drop better without losing flow than 2 smaller ones will.
If you only have a single 2 or 3 core radiator with no other coolers then 2 smaller fans could well perform as good - maybe even better.

I have a 16" davies craig as my main fan which draws through from the rear of the radiator and then 2 x 12" fans mounted in front blowing through which work as both secondary cooling and/or A/C condenser fans.

I did a bit of an experiement pulling the relay on the primary fan to see the difference.

The 16" fan can easily cool the engine even in the rotten 37 degrees we got over last x-mas on it's own but even on a 28 degree day the 2 x 12" ones couldn't force enough air to keep the engine under 110 degrees at which time I shut down the test for fear of doing damage.

If space is a premium and you need to fit smaller fans, you can even run them in a push-pull configuration with one on front and one on the rear of the coolers and this will improve the airflow as well - the fans will 'share' the pressure drop across the coolers and the airflow will increase as you are operating higher up the fans droop curves.

 

[Dreamkiller]

One 16" fan will pull just more air than 2 x 14" fans!

 

[Lextreme II]

i guess i have two 16" would be over killed.

 

[Dreamkiller]

Damn!, you live on Mercury or something.

 

[Lextreme II]

LOL.. right now my temperature sender is not install and i am running my two fans with a 30 amp relay and I have to replace my relay once every two months or so. Too much amps going to the relay.

 

[Zuffen]

Guts,

Try the Ford EB and later fan set-up. Cost around $300.00 and if you can seal around the edges it will do lots of good. I have one on my Rangie and it works a trat.

The blades are scolloped to keep them quite (like a nuclear sub!) so won't work too well in reverse (but neither does a nuclear sub).

David,

Why not replace the 30 amp relay woth 2 x 30 amp relays. One driving each fan. In 4 months you will have paid for them and not need to replace them again.

 

[Lextreme II]

I am putting on temperature sensor/sender in my 1uzfe. The fan will only goes on from a given temp and turn off at a given temp. No more relay. direction. The adapter is custom. 3/8 npt female with 20mm male.

 

[Zuffen]

That 20mm adaptor must be different in the US.

I had to get a special fitting from an hydraulics specialist as the pitch is different to a normal plumbing fitting.

You may need to double check.