Replacing The Radiator Fan With Electric Fans. Performance Benifit?

[Bass Junky]

I've got a big thermo for sale from when I went back to the standard engine fan.

I had trouble with keeping her cool on hot days, and the temp would go from 80 when the car is moving at 40+kph, and rocket to 95 at standstill with the thermo fan busting it's ass.

Just couldn't trust it to keep her cool enough.

[CEF11E]

a lot of cars now run thermo fans as standard oe equipment. and if they have a shroud like the standard fan they work well. its when they do not have a shroud that they are inefficient.

one case i know of was a brave 4x4 that had a thermo fan fitted and he gained about 40 k's per tank. thats a pretty decent fuel saving. provided its a decent fan with the power to draw enough air thru the radiator i think its the way to go.

i am going to be replacing the fan on my track car with thermos and see how it goes.

[blind_elk]

... wen my motors usually on i just turn it down to the lowest temp so its always on...

That pretty much defeats the purpose of installing thermo fans.

The principle is based on the fact that when the car is moving at a reasonable speed there is sufficient airflow through the radiator to maintain the thermostatted temperature. At idle, the engine can tolerate slightly elevated temperatures, until a point when you need to provide some fan-forced cooling. Once the car gets moving again, the airflow will cool to thermostatted temperature again. (This is how my R30 works)

As in my experience (in the R32), if you can't get enough air to flow through the radiator, you are going to have trouble maintaining coolant temperature control.

If you have to have the thermos running all the time, then the system is not working correctly.

[SkyHi_33]

anyone tried using ef-el falcon thermo fans? you can pick them up for about $200 brand new with the shoud and all.. only problem is getting them fitted up but that should not be a huge problem... they cool the ol 4L very well, and are pretty slim so should fit in nicely too.

Im considering doing this sometime over the weekend... will let you know how it goes.

[Dose Pipe Sutututu]

I go for stock clutch fan any day of the week, Nissan put it there for a reason, because it works and it serves its purpose efficiently and effectively.

In my old car, I ran 2x 12" Davies Craig fans, and I can tell you I would have swap it for a Clutch Fan any day of the week if it could fit, (RB20DET in a 180SX)

When you think about the stock clutch fan, the blades have a greater surface area than most electric fans, i.e. it's able to deliver more airflow and the benefits of having a clutch fan is not having to worry about blown fuese, dead fans, fcked thermostats, load on the electrical system, etc.

On my old car, everytime the 3x thermos kicked in, (2x behind radiator, 1x in front) the idle would drop dramatically or the car would hunt, annoying as fck and when you think about it, 3x thermos would draw close to 40amps of current on load.

[juggernaut1]

40 amp current draw ....strewth....throw those in the bin. Also problem with the Davies Craig fans is that they don't draw air through the entire radiator due to the lack of a proper shroud. Look at the way most manufacturers do them these days.

Heres an excerpt from a Ford Forum regarding current draw of the AU falcon fans which are 2 x 12 inch fans:

"There have been some queries regarding the required amperage of the alternator to run AU fans, hence I measured the current draw of the fans and got the following readings.

At low speed = 3.6 Amps

At high speed = 13.5 Amps"

Here's a pic of the AU Falcon fan setup in my s15:

I have these setup on low and high speed and controlled by the ECU - you wouldn't even know there on at low speed with low noise and negligible current draw. High speed hardly kicks in unless aircon is on.

[Dose Pipe Sutututu]

you're forgetting on the initial startup there's a massive current draw, I had all 3 fans on separate relays with 15 amp fuses, and on the odd day one would pop.

so I'm guessing with all 3x thermos kicking in there's in excess of a 40amp draw, I couldn't measure it as my multimeter only supports to up 10amps, what the heck, I don't own the car anymore..

I got a R33 with a stock clutch fan and it serves it purpose so much better than 3x thermos ever did, that's with A/C on, on a 35+ degree day, and pushing the car.

each to their own.

[bubba]

I've got 2x11" thermos that I'm throwing in front of the radiator (removing aircon condenser and dryer/receiver), not removing clutch fan though. This is for extra cooling during burnouts and while sideways.

Is there a bigger alternator we can use on our skylines?

[Dose Pipe Sutututu]

I've got 2x11" thermos that I'm throwing in front of the radiator (removing aircon condenser and dryer/receiver), not removing clutch fan though. This is for extra cooling during burnouts and while sideways.

Is there a bigger alternator we can use on our skylines?

get your alternator recoiled or I was reading you can use the Bosch/cop alternator from the VS commodore, but you need to cut and shut the plug as their different, it's like 120amps compared to 80amps

http://www.calaisturbo.com.au/showthread.php?t=11447

yeah I know bogan site, but sometimes useful

[discopotato03]

This won't sound right initially but it makes complete sense if you think about it .

Fact 1 , radiator fans are there to control the temperature of the water in the RADIATOR not the engine .

Fact 2 , IF the temperature of the water in the radiator is the same as that in the engine it can't reduce the engine water temp .

For a cooling system to work properly the coolant in the radiator MUST be cooler that that in the engine . When it is then the water thermostat can maintain a steady temperature in the engine .

So elec fan sensors need to switch the fans on BEFORE the temperature of the water in the radiator reaches that of the water thermostats rating .

IMO the reason why the mechanical fans work so well is that they run all the time and the temperature of the water in the radiator can be quite low - remember its the water thermostat controlling the engine water temperature .

For some curious reason some people try to use electric fans and sensors to read engine water temperature rather than rad water temp . They set the fan switch to come it at say 90 odd deg C - meaning when the entire cooling sysyem is at 90 C meaning all the water in the engine and the radiator .

The poor old elec fans end up on their knees trying to drag the heat out of the entire volume of coolant rather than just whats exiting the engine .

Had the fans been maintaining say 60-70 deg C in the RADIATOR then there would be a cool water reserve to enter the engine when the thermostat opened up wide and a steady temperature is easier to regulate .

I think its silly to try to regulate engine temperature with elec fan thermostats when the factory supplied a water one to do just that .

As for the fans running too long , its either because they don't move enough air or they were set a bit high temperature wise .

A couple of other interesting things , Davies Craig say that their fans move more air in push mode than pull mode .

Quite often one big fan works much better than two smaller ones . Radiators in these cars are wider than they are high and the std fans diameter is not equal to the width of the rad core .

I had twin DR30 elec fans and an R32 GTR rad in my old FJT'd Bluebird and I got it to work quite well with a bit of experimentation .

Bottom line , if you can't control rad water temp it can't cool the engine itself .

Lastly if elec fans are set high the post rads air temp is also high when they are running and they dump all that heat primarily in the engine bay .

Personally I'd rather have the fans maintaining the rad temp lower and having them pull warm rather than real hot air into the engine bay .

My thoughts only , cheers A .

[rev210]

A 'good' thermofan setup is better than the clutch fan.

The intercooler and radiator have efficiency improvements if you take the time to shroud them. This = more power and easier cooling.

You can buy the radiator guides for GTR's from a bunch of places but, if you really want to do it right pop the front bar off and create a guide around both the radiator edges and intercooler edges to ensure the air is draw/ guided through the cores more efficiently. You can fabricate pretty looking ones from metal or even just using slightly ridgid foam on the cheap and backyard side.

ALWAYS use or make a fan shroud and where possible use the moulded factory style one.

The shouding rule applies to oil and trans coolers as well.

Twin davies craig 12 inch fans are lower cfm rated than the big 16 inch one, if you had to use that brand twin 12's is a bad move. Davies craig fans are pretty crap compared to the factory units availible.

The twin thermos from later model cars are better again than the AU falcon unit.

[2BNVS]

interesting topic as im thinkin of doin this too atm, very hot qld summers lol

[Bliksem]

Those AU thermos look very neat. I was intending to use a 16" ive had sitting around suspended in the factory shroud.

[SkyHi_33]

I go for stock clutch fan any day of the week, Nissan put it there for a reason, because it works and it serves its purpose efficiently and effectively.

In my old car, I ran 2x 12" Davies Craig fans, and I can tell you I would have swap it for a Clutch Fan any day of the week if it could fit, (RB20DET in a 180SX)

When you think about the stock clutch fan, the blades have a greater surface area than most electric fans, i.e. it's able to deliver more airflow and the benefits of having a clutch fan is not having to worry about blown fuese, dead fans, fcked thermostats, load on the electrical system, etc.

On my old car, everytime the 3x thermos kicked in, (2x behind radiator, 1x in front) the idle would drop dramatically or the car would hunt, annoying as fck and when you think about it, 3x thermos would draw close to 40amps of current on load.

What else did you run apart from the 2x12" fans?

did it have a proper shroud?

did it have a thermo switch located ON the radiator?

how did you wire them up?

People often forget that its not the fan that makes the difference, its the shroud directing the flow through it. If you just slap on 2x12" fans on to the radiator without a shroud and no spacing between the core and the fan itself, what you're doing is wasting your time by cooling only that area of the radiator.

Hence why Id like to switch over to EL-AU twin thermo setup, they have a very efficient shroud and are quite tough units. On top of that I will be wiering in a thermo switch reading temperatures from the return pipe as it is where the heat is comming from not engine (as stated above).

Main reason behind me doing this is

1. ive had 2 fan clutches go on me and one has ruined my water pump.

2. it frees up some space

3. engine revs a bit better without the drag of the clutch fan

i dont particulary care about number 3... but its other two that are important.

I will be picking up parts before weekend and will try get some pics of the setup and installation/results after the weekend.

[Dose Pipe Sutututu]

ran 2x12" DCSL12 fans, 1x Stock 12" A/C Condenser fan

No shroud, as there was no room (RB in a 180SX)

Thermo switch located at the bottom of the radiator tank, with thermo switch swapped from the stock 90 degree one to a mitsubishi lancer one which activates at 82 degrees

Wired all 3 fans to separate relays, straight to battery, thermo switch went to ignition power, then to the trigger on the 3 relays, diode was used to switch only 1 fan (the A/C condenser fan) when A/C was on and another diode was used to stop the A/C compressor kicking in when the thermos were on.

I had no choice of what to use, was either thermos or nothing, and there was no room for a shroud.

But saying all of that, my current car has the stock clutch fan & shroud and I can tell you I won't be changing it at all.

[juggernaut1]

you're forgetting on the initial startup there's a massive current draw, I had all 3 fans on separate relays with 15 amp fuses, and on the odd day one would pop.

I know its not an exact measurement of current draw but my tacho doesn't dip at idle when the low speed comes on.

Moreover, most modern cars have three thermo's and I don't see fuses popping - your 15 amp fuse may have been too low - I run 2 x 30 amp fuses on the basis the standard single thermo fan on the s15 is 30 amp. Also I guess when the speed of the fans is staged it doesnt result in a high current draw which your car may have had when pulling the fans on straight to high speed.

Edited January 21, 2009 by juggernaut1

[SkyHi_33]

ran 2x12" DCSL12 fans, 1x Stock 12" A/C Condenser fan

No shroud, as there was no room (RB in a 180SX)

Thermo switch located at the bottom of the radiator tank, with thermo switch swapped from the stock 90 degree one to a mitsubishi lancer one which activates at 82 degrees

Wired all 3 fans to separate relays, straight to battery, thermo switch went to ignition power, then to the trigger on the 3 relays, diode was used to switch only 1 fan (the A/C condenser fan) when A/C was on and another diode was used to stop the A/C compressor kicking in when the thermos were on.

I had no choice of what to use, was either thermos or nothing, and there was no room for a shroud.

But saying all of that, my current car has the stock clutch fan & shroud and I can tell you I won't be changing it at all.

yeh fair enough...

Ive had really bad luck with the fan clutches and its cost me over $400 to get it all fixed up yet the clutch on there has just died again... it locks instead of releasing therefore the fan spins at the same speed as the engine. bad for the water pump and your bonnet insulation.

went out and picked up BA falcon twin thermos and shroud from a wrecker for peanuts. the shroud mounts were snapped off so the wrecker gave it to me half price. doesnt bother me as i gotta make new mounts anyways

putting it up against the old equipment it seems to be the same thickness so should clear perfectly fine. next step is finding a proper thermo switch and hooking it all up

Edited January 21, 2009 by tx3_90

[bubba]

I will be trialling a particular thermo switch if I can find it, it's on at 85 and off at 80, apparently out of some Magna - the v8 boys use them.

[Adriano]

You can get thermo switches with different temos and threads from Auto one.

[sav man]

have any of the people that have had over heating problems been running a shrowd? I want to piss my clutch fan off just cause it's a pain to remove if i need to work on it.

Those AU ones look pretty good, is the raidiator in a AU about the same dimentions as a skyline?