Thermo Fan Install Questions "turn On When?"

[Pete K]

Hi All,

I had a bit of a look around and it seems there is allot of debate about electric thermo's so i dont really want to open a can of worms but im after some advice.

Seeings as im preparing my car as a dual purpose machine, as a daily and for the track i have recently installed a new 40mm ally radiator, and changed the thermostat to the highflow version. when the other day I noticed that the fan was always on high speed even at start up, i had a close look at the clutch and it looked to be a sealed unit but noticed some cracks in the fan blades, and that it was out of balance due to someone before me cutting the blades for the fmic piping. So i decided to do an electric thermo fan conversion for 2 reasons, the new fans worked cheaper then the clutch assembly and more importantly i wanted the fans to continue to run on after i shut the car down to aid heat soak and aid with the waters thermo cycling to help protect the turbo.

Im just wondering what others have used to cycle the fan on and off. im thinking of a temperature switch. i can buy one like i read on the forum thats on at 85degc and off at 80 deg c, but it looks like the only place to put it would be where the temp switch is to put on the ac thermo on in the lower drivers side of the radiator. I have an ally pipe fitting that will be going in my top radiator hose for my temp gauge sender but im unsure of the correct placement of my fan temperature switch. What have others found works best for fan control? i like the simplicity of the basic temp switch. Has anyone used the PowerFC to control the fan as this would be ideal. I cant figure out how to do this and im not even sure if its possible
What makes this hard is im unsure of my cars normal operating temperatures, and if it constantly wants to sit on 85deg i dont want the fans running all the way along the free way,

By the way i couldn’t fit the au dual fans in due to the power steering lines, but i managed to fit a bf-fg single fan in there. Ive only run it with my little prawing battery that was running at 11.3v and the fan was unbelievable, cant wait to see it at 13.5v

any advice would be great,
Cheers Pete

[Dale FZ1]

Power FC won't be configured to control thermos. Many/most current type aftermarket ECU have the ability though.

There are stand alone control units available that will do a good job.

I find mine does a good job with a kick-in point of 94 degrees and switch off at 91. Sitting at idle it cycles in/out more frequently so it's only a preference. Properly functioning OEM fan probably does the best job for a car doing lots of idling and slow traffic work.

Hopefully the shroud fits your radiator nicely and is sealed around the edges to make sure the majority of air is pulled through the core. Adhesive rubber tape does a great job.

No point having fans continue to run after the engine is shut down, not enough coolant will circulate through the engine to make an appreciable difference. If you're concerned about track use, simply idle the engine for 3 minutes after a run/race while you check the car over. Lift the bonnet and let hot air dissipate from the engine bay.

Thermo conversion is not a must-have but I found it certainly is not a bad thing. A really flash setup would probably be with twin fans controlled to come on in a staged manner according to temps. Lower fan noise and electrical drain so easier to control idle speeds too.

[Dose Pipe Sutututu]

just use an OEM style thermo switch that bolts in the bottom of your radiator... you can easily go through the Tridon catalog and select whatever temperature you like..

I've done this before and wired that back to 2x horn relays to 2x 12" thermo fans on my S13 back in the days.

Ideally you want one that has some form of hysteresis...

[Pete K]

Im hoping the fan should do ok, it will suck an A4 paper against the intercooler when its 400mm in front of the intercooler, i have some wide sticky foiled bituman flashing i was going to fully seal it up with but it sucks so strong i dont want it to be sucked in, so i just made an aluminium shroud on the top heres a few pictures,

[Pete K]

Ideally you want one that has some form of hysteresis...

Yeh, i really dont want it constantly turn on and off, every time it moves 1 degC

[Dose Pipe Sutututu]

I can't remember the exact details.. but when I did it back in the days I pulled one off a Lancer and chopped the loom that went with it.. the fitting was the correct size for the Skyline radiator.

[Pete K]

No point having fans continue to run after the engine is shut down, not enough coolant will circulate through the engine to make an appreciable difference. If you're concerned about track use, simply idle the engine for 3 minutes after a run/race while you check the car over. Lift the bonnet and let hot air dissipate from the engine bay.

im going to have a vented bonnet and i want to lift the rear of the bonnet near the windscreen about 15mm to let the heat out, as it may not always be practical to leave the bonnet open, track days for sure it will be left up. the thermo fan will blow a face washer off the standard throttle body with the bonnet open so im sure there is some benifit on having it on if the air has some where to go once stopped

did you put a manual bypass in your system?

cheers

[juggernaut1]

Here is my hi/low speed Falcon AU fan setup controlled by an Autronic through a modified fuse box (for dual fans) and stock ECU temp sensor in my S15. Low on at 85 and off at 80. Not sure what the high settings are as it doesn't exceed 85 once the low fan speed cuts in. In your case you could go a dedicated adjustable fan controller which would allow you to adjust temps accordingly. http://www.spal-usa.com/fans/automated/accessories/fanpwm.html

Edited August 11, 2014 by juggernaut1

[discopotato03]

There is a logical reason why many people get the elec fan switch points wrong and it's basically this .

For a radiator to cool an engine the water available from it must be below the temperature you want to run the engine at . Basically the water thermostat regulates the engine temperature but only if it can let cooler water in than the block and head have inside them . If the water coming in is the same temp then the engine temp will rise .

I believe the stumbling point is that people measure the temperature of the coolant inside the engine (head or inlet manifold log) and use that as a basis to set elec fan thermostats . The problem is that the fan/s are cooling the water in the radiator not the engine and the water thermostat is attempting to regulate engine water temperature .

You can have a situation where the water thermostat and fans electrical thermostat fight each other and temperatures can go all over the place .

I think if you must run elec fans regulate them from the radiator not the engine water jackets because then the water thermostat does what it's supposed to do .

The standard mechanical fan system works so well because it drags lots of air through the radiator core creating a reserve of cool water which the water thermostat lets in when needed . With no fan running average radiator temps are generally higher so the reserve of cooler coolant often isn't there , it won't be because the elec fan control is looking at engine temp not radiator temp so as the engine temp rises so does the radiator temp . By the time you decide to hit the fans they have to drag the heat out of the whole cooling systems volume not just what's inside the engines jackets . A sensor in the bottom radiator tank would be the go because the temperature difference top to bottom can be considerable and its water from the bottom that goes into the block as the water thermostat opens .

If as you said you were cruising on the expressway the radiator should be doing its job and water low down in it should be low so the elec fans mostly won't run .

It's this coolant reserve between the top and bottom tanks that makes all the difference and why the factory system is so effective when it functions as Nissan intended ie belt hub fan shroud .

Optional opinion , I reckon most late north south engine cars have elec fans because emissions regs are so tight , particularly at cold start , that the manufacturers are forced to do everything possible to have the least load on the engine and run them as lean as possible . Things like low friction multi rib belts and PCMs that lower alternator charge rates to minimise parasitic losses for emissions and consumption reasons . Longevity isn't what it once was and longer maintenance schedules ensure most garden variety cars today won't be here in 15-20 years time . I don't think manufacturers give a rats what their creation is like beyond a certain age and mileage because they want cars to be consumed thrown and replaced . Obviously new ones can stand up to less than ideal circumstances for a time but beyond warranty period tough luck .

An R33 is now 17 to 21 years old and IMO over engineered in some areas compared to many of todays "cars" ...

A .

[Pete K]

Thanks for the input , i know manufacturers only build for just outside the warranty period, not because they dont give a crap or can do no better but because in order to remain competitive they must reduce costs and ensure there brands future. Longevity is a really hard balance for manufacturers, last to long and it wont be replaced and wont be affordable, or make it really cost effective and end up with a bad reputation due to reliability issues. this issue is what has made it so hard for Australian manufacturing trying to compete with low overseas wages.
My understanding is most modern cars run electric thermos as it is a far more controllable way to manage the engines running temperatures. Like you said emissions are such an issue that they need the cars to run as hot as possible and within a very tight temp band.

having said that, the r33 thermo i believe is a 76.5 deg c. is this when it starts to open or when its fully open?

and at what temp should i try to keep the car. ive herd people running around with temps ranging from 75 to 110. Surly there is a recommended temp

if i put an 85 degC thermo switch in the bottom of the radiator i guess the block temp will be well over 90deg leaving the motor before the fan decides to start.

if that makes sense

[Pete K]

Here is my hi/low speed Falcon AU fan setup controlled by an Autronic through a modified fuse box (for dual fans) and stock ECU temp sensor in my S15. Low on at 85 and off at 80. Not sure what the high settings are as it doesn't exceed 85 once the low fan speed cuts in. In your case you could go a dedicated adjustable fan controller which would allow you to adjust temps accordingly. http://www.spal-usa.com/fans/automated/accessories/fanpwm.html

WOW that sure is one very tidy setup, i wish under my hood looked like that, its so hard to find a tidy skyline. Part of this prep work im doing is involving removing everthing i can from the motor, degressing it, painting it, cleaning the engine bay and putting it all back together. but my baby has markes and holes cut in her everywhere.

[juggernaut1]

Lol...the above pics were the start of something that ended up morphing into this:

[Pete K]

NICE!!!!

[Dose Pipe Sutututu]

engine pr0n

[Dale FZ1]

Pete my system works pretty well with the switch on/off points as described. So it has hysteresis. Being controlled by my ECU, it uses the temp sensor housed in the upper section of the inlet manifold as per stock. I'm more concerned with the coolant temps in the engine, not the radiator.

Raising the rear of the bonnet is the old hot rodder's trick and I wouldn't use that method unless it was being trundled around at low speeds always. As road speeds rise, high pressure air forming at the windscreen base is likely to have a detrimental effect on airflow through the engine bay, and may result in a drop in the air mass going through your radiator. Leading to a tendency for reduced cooling efficiency when you really need it on the track.

Some of these things you need to trial/error and ultimately use what works for you. Everyone is an expert on forums so expect conflicting information and views when chasing advice or opinions.

That S chassis engine bay does look good.

[discopotato03]

I gained my experience from elec fan cooling an FJ20ET in a Bluebird , bulky engine in a car that had cooling issues with the single cam carby L20B in it .

I was using the DR30s factory radiator and fans and later an R32 GTR radiator in that car .

The only reason I didn't run a belt driven fan is because it wouldn't physically fit .

OT but the factory system in R and S series is very effective , if it wasn't the world would be full of dead and dying Silvias and Skylines .

[juggernaut1]

OT but the factory system in R and S series is very effective , if it wasn't the world would be full of dead and dying Silvias and Skylines .

Agreed they work very well on those Nissan's DP.

But if thermos didn't work the world would also be full of dead and dying Commodores, Falcons, Toyota's and every front wheel driver too.

I have personally found the Falcon AU fan setup very reliable and very effective on my S15. Even on low speed air is pulled through both the air-con condensor and intercooler. My FG G6ET also runs a similar dual speed setup from the factory and works a treat - high fan speed rarely comes on - as the low fan speed is sufficient for most conditions here in WA. My brother's twin turbo VZ Commodore has no probs with the factory thermo fan setup either.

They key IMO is use a decent shroud coupled with an adjustable fan speed controller and from then on its a case of trial and error. Also pretty sure most manufacturers base their temps off the ECU temp sensor rather than a radiator temp sensor.

I did use a Davies Craig thermo fan conversion on my Escort RS2000 back in the day with the probe in the top of the radiator inlet, as per the instructions, and it was a total fail.

Edited August 11, 2014 by juggernaut1

[Dose Pipe Sutututu]

Those Davies Craig fan controller probes are junk.. a simple OEM style thermo switch works tits

here's a thread I participated in back in the day.. most of the images are missing but you get the idea:

http://www.nissansilvia.com/forums/index.php?showtopic=309986

[juggernaut1]

Here's another which shows the additional relay required to run the fans in series to obtain the low speed fan.

http://omgpham.com/nissan-s15-thermo-fan-setup

[Roy]

just use an OEM style thermo switch that bolts in the bottom of your radiator... you can easily go through the Tridon catalog and select whatever temperature you like..

They wiped me when I tried to get a plug that goes with the switch. Told me I had to go find that model car at the wrecker and grab the plug from the loom (FARK that...want a new plug to go with my new switch Thoughts on where to get associated plugs?