Thermo fan info

[chimpboy]

Thought this might be useful to some people eg when converting to electric fans.













Pinched from another forum.

[DL]

Thanks CB!

I have fake EL thermos with stock RRC rad cooling 350 Chev. Second fan runs on adjustable switch, first fan is on all the time which is excessive.

Sometimes in winter it doesn't even get up to normal op temp and I was looking for a cheap option to switch first fan on only when up to temp.

cheers, DL

[murcod]

This might be of interest to anyone who is using dual thermofans:



Note the use of the Tridon 2FS 214 thermal switch which has two inbuilt switching points. (Info originally from here http://www.fordforums.com.au/vbportal/f ... diagram+AU )

I'm also currently converting my Suzuki XL-7 using a similar circuit, but instead employing two Jaycar Universal Voltage Switch to do the temperature switching. That way I've got adjustable switching points (and hysteresis) plus I can use the factory ECU temp sensor to get the reading. I'm using a Spal dual 11" thermofan with built in shroud- but the circuit would work fine for any dual thermos.

[DL]

That's great!

This should really all be a sticky.

Chimpboy............. how well do you know the big chimp?

[chimpboy]

Below are specs for Davies Craig thermo fans. Should do as at least a rough guide for other brands' current draw, cfm etc. One thing to note is that although a lot of people go for the dual 14" fans, the total flow is better from a single 16".

[murcod]

I'd highly recommend checking out Spal fans over Davies Craig, they're a bit harder to find in Australia but there are some bargains on ebay.com

http://www.spal-usa.com/

[chimpboy]

I'd highly recommend checking out Spal fans over Davies Craig, they're a bit harder to find in Australia but there are some bargains on ebay.com

http://www.spal-usa.com/

For the record, I'm definitely not pushing these particular brands... just gathering together some rough data for people thinking of using electric fans.

[murcod]

I'd highly recommend checking out Spal fans over Davies Craig, they're a bit harder to find in Australia but there are some bargains on ebay.com

http://www.spal-usa.com/

For the record, I'm definitely not pushing these particular brands... just gathering together some rough data for people thinking of using electric fans.

Sorry, I wasn't suggesting you were! A lot of people don't realise there are a lot of higher performance fans out there- most people in Australia just naturally think of Davies Craig and don't look into it any further.

I was just adding on the link to add to the informative nature of the thread. There are spec sheets for the Spal fans on that website I posted so people can do comparisons for themselves.

Spal also make a larger selection of fan sizes (including dual 11" and 12" shrouded versions) plus straight/ paddle or curved bladed options.

Flexalite also make some high peformance fans and even have kits out for converting common USA model 4WD's eg. Jeeps. http://www.flex-a-lite.com/auto/html/electric-fans.html

[chimpboy]

I'm also currently converting my Suzuki XL-7 using a similar circuit, but instead employing two Jaycar Universal Voltage Switch to do the temperature switching. That way I've got adjustable switching points (and hysteresis) plus I can use the factory ECU temp sensor to get the reading. I'm using a Spal dual 11" thermofan with built in shroud- but the circuit would work fine for any dual thermos.

I have been thinking about this since you posted it... actually since before you posted it, mulling over the most logical relationship between the fan switch/temp sensor and the car's thermostat.

My thinking is that I am not 100% sure I like the idea of picking up the fan switching temperature from the engine side of the thermostat. I think it is better to have it on the radiator side of the thermostat. But I dunno. I would really like to hear all the different thoughts on these setups. I've even done a few saucepan tests of switches and thermostats to get the juices flowing.

First, some facts that I think are pretty solid:

1. It is the thermostat's job to be the primary ruler of engine temperature. Generally speaking a thermostat begins opening 2-3 degrees below its stated temperature and is fully open about 11 degrees later. So an 88-degree thermostat opens slightly at ~85 degrees and is fully open at ~96 degrees. Obviously different makes vary slightly. And some older thermostats may have both an opening and fully open temperature stated.

2. Assuming your coolant is sufficiently cooled by the radiator, the exact temperature that your thermostat maintains in the engine will depend a bit on the engine, water pump, radiator, etc. It won't necessarily be exactly 88 degrees for an 88-degree thermostat but it will be in spitting distance of that.

3. If your cooling system is right, your thermostat will never actually fully open. It will oscillate between fully closed and partly open, but if it gets fully open then you've essentially lost control of the engine temperature.

4. Slightly off-topic, but still a relevant fact - both engines and cooling systems are more efficient if the engine runs at a higher temperature. Basically the hotter the better as long as the engine design permits. Too hot kicks in when different metals expand differently (so bearings fall out or whatever), or when materials soften or warp. But there is no sense in any idea that cooler = better. Stable is the goal.

...

I think those statements are solid. Now here's my speculation. Purely looking at an electric-fan-only arrangement; if you have a mechanical fan as well then it's totally different.

5. The fan should switch ON at a temperature lower than the fully-open temp of the thermostat. So if the 88-degree thermostat is at approx. 85-96 degrees from closed to fully open, the fan should kick in at no higher than 96 degrees.

6. The fan should also switch OFF at a temperature higher than the fully closed temp. So, if you have an 88 degree thermostat that is at approx. 85-96 from closed to fully open, a fan switch that such as a 95-On, 90-Off would be the go.

7. If your fan switches OFF at a temp lower than the fully closed temp of the thermostat, it is pretty much going to run 100% of the time IF the temp sensor is on the engine side of the thermostat. That's the scenario that I think is not quite right, but it probably is okay if you have an adjustable switch and you adjust it correctly anyway.

I have fitted an 88-degree t'stat and a 95-on/90-off fan switch, with the fan switch in the t'stat housing on the radiator side. I can't report on how well it works yet but I am hoping it will maintain a pretty constant running temp.

Anyway, I could have this completely wrong. So what do you reckon?

[murcod]

Yes, I'd agree with probably all of what you've said. A lot of those points you've mentioned are also why I'm going for adjustable switch on points and dual speed.

This is my second conversion and I learnt a lot from my first on my old Feroza. For a start don't use those harnesses supplied with fan kits (eg. the Davies Craig kits)- the wire is simply too small and drops too much voltage, even a slight drop will be very noticeable in fan speed. Use 6mm squared cable minimum.

I'm also going dual speed because that's what most modern factory setups do. It also means greater regulaltion control over the coolant temp - you're not trying to suddenly cool things once they are starting to get too hot (which is often the case with a single speed fan.) On my Feroza it struggled to pull the temp down on 40 + degree days with the A/C on.

The controllers I'm using are adjustable for switch on points and at the moment I'm monitoring what constitutes a "normal" coolant temp sensor voltage range with the viscous fan fitted. I'll be setting my low speed fan point at the top of this range and high speed slightly out of this range.

I'm doing the monitoring to ensure that I'm not "fighting" the thermostat (ie. cooling the coolant so much that it will be closing.) I know that the coolant sensor voltage oscillates around 0.545 -> 0.555V on cold days at 60km/h plus, so this would appear to be the set point maintained by the thermostat and i don't want the fans running when close to that range.

The factory systems also use the ECU coolant sensor (from what I've seen) which is in the block. However I can see the merits in possibly locating it at another point (eg. radiator outlet hose to determine if the radiator is cooling enough before the coolant enters the block.)

I dearly wish that my Suzuki was OBDII compliant as that would make monitoring everything so much easier. Instead of monitoring voltages I would be reading actual coolant temps.

[MightyMouse]

Tried the voltage sensitive switch system and found the following...

Little ecu coolant temp voltage variation at operating temp - The ECU coolant sensor is mostly used during warm up and is non linear. Had to completely remove the hysteriesis and disable the input divider

Variation in ECU reference voltage caused shifting of switching points with differences in electrical load.

Ended up going to a temperature controller ( jaycar again ) with a seperate sensor - now works fine.

Sooooo - check exactly how stable, what voltage and span is available from the ECU coolant sensor BEFORE you get too carrried away. Would work fine with some and be a PITA with others makes and models.


Also whilst im ranting.... have a look at the flow specs of a Davis Craig vs SPAL for example. When in free air they both appear to flow almost the same. But look at the figures when operating with a restriction - the Davis Craigs falls in a heap - a sign of pretty average blade design.

And...... there are blade sets for Push and Pull applications and it does make a difference. Anyone who says "one will do both" is probably just proving how bad their blade design is.

[murcod]

For anyone who's interested I've got more info on how I'm doing my conversion on this forum: http://www.suzuki-forums.com/suzuki-vit ... o-fan.html

[murcod]

Tried the voltage sensitive switch system and found the following...

Little ecu coolant temp voltage variation at operating temp - The ECU coolant sensor is mostly used during warm up and is non linear. Had to completely remove the hysteriesis and disable the input divider

Variation in ECU reference voltage caused shifting of switching points with differences in electrical load.

Modern factory EFI systems use the same sensor to control the switching of stock electric thermos, and do so very accurately. So there's no reason why an aftermarket add on shouldn't work just as well.

Yes, I've found the factory sensor "normal" range with the viscous fan on is small (around 0.06V variation.) However that is the range measured with the viscous fan operating - so in theory the electric thermofan wouldn't need to be on until the voltage got somewhat outside that normal region.

I have modified the Jaycar circuit and have got the hysteresis down to around 0.025V which should be more than ample. The only reason why I've gone that low is because I'm using two controllers to give me dual fans speeds- if it was a single speed set up it wouldn't need to be that low a voltage difference.

The reference voltage shouldn't vary greatly and perhaps might be a vehicle specific problem?

[PJ.zook]

Just fitted a thermo fan into suzuki and buggered off the mechanical fan, works fantastic, turns on for about 15seconds every 3min or so to keep the G16B at operating temp. The fan im using is a 16" i got off ebay for about $40, will see how long it lasts, as its about a 10min job to remove thermo and fit the mechanical fan back on if it fails. I found 16" is a little big though, its larger than the fin n tubes, and only just is short of beign longer than the end tanks.

[Dooley]

Just thought I'd add my 2c.

I've been getting prices on new thermoswitches and if you can pick whatever you like and are just going on the switching temperature, get prices for all in that switching range.

For my Sierra, (90 ON - 85 OFF) prices for a Swift/Sierra listed one are $78 + GST (TFS 116) . The Price for another one was $30 + GST (TFS 109). Plus the 109 has spade terminals rather than some obscure connector...

[stuee]

I'm surprised there's no mention of the falcon EA-AU thermo fans. These are available everywhere, in both genuine and after market form. Can be had from the wreckers for real cheap and have been successfully adapted to many different radiators with a bit of modifying.

They also have the advantage of a nicely moulded shroud that aids in sucking through heaps of air.

These are the AU thermos that I've got and going to be fitting to my Discovery soon.





Also in terms of temperature senders I'm going to be looking at getting a block mounted sensor similar to what's used in the engine saver kits. Not a water based sensor but one that slips under a head bolt other similar location. This should give me an indication of when the the cooling system has failed too.

[murcod]

I looked at them, but they're very wide and not very tall- not really suited to a lot of 4WD's. They were something like 7cm too wide for the radiator core on my V6 2.7l GV XL-7!

They would have been hitting the chassis rails both ends.

[stuee]

I looked at them, but they're very wide and not very tall- not really suited to a lot of 4WD's. They were something like 7cm too wide for the radiator core on my V6 2.7l GV XL-7!

They would have been hitting the chassis rails both ends.

Haha. I'm the complete opposite. On the Disco they're too skinny and stick out over the top of the radiator

[murcod]

I can recommend the Spal dual 11" fans- they're doing a fantastic job on my Suzuki XL-7 in 46 degree heat. They also make 12" duals as well, but once again they were too big for my core. http://www.spal-usa.com/fans/automated/ ... 102130.pdf

The only issue will be the price, I bought mine from the USA when the exchange rate was 0.96.

[murcod]

Tried the voltage sensitive switch system and found the following...

Little ecu coolant temp voltage variation at operating temp - The ECU coolant sensor is mostly used during warm up and is non linear. Had to completely remove the hysteriesis and disable the input divider

Variation in ECU reference voltage caused shifting of switching points with differences in electrical load.

Ended up going to a temperature controller ( jaycar again ) with a seperate sensor - now works fine.

Sooooo - check exactly how stable, what voltage and span is available from the ECU coolant sensor BEFORE you get too carrried away. Would work fine with some and be a PITA with others makes and models.

I've had mine up and running for a week now. Given the "heat wave" in Adelaide over the past 7 days I've been highly impressed with how well the Spal dual 11" fans work.

It was actually running cooler when caught at traffic lights when compared to a 2 degree cooler day running the viscous fan (that was comparing a 43 degree day to a 41 degree day.) I'm also comparing the ECU temp sender voltages- the temp guage doesn't fluctuate enough to tell which system is better.

Even a 46 degree day wasn't a problem. That includes the A/C on and driving up a steep hill -which was the downfall of my old Feroza conversion on 35 degree plus days.

I am having some issues with the voltage fluctuations you mentioned MM (fans can kick in in time with the indicators etc ), but have revised my wiring. Part of the problem was the earth to the chassis for the Voltage Switches was varying slightly in voltage- so I've now got the Voltage Switches earthed directly to the battery negative and am using a separate earth for the onboard relay switched output (which in turn earths the 60Amp relay coils for each fan to provide the dual speeds.)

Differences as little as 0.05V in the system constitute "major" temperature changes, so every little voltage drop needs to be taken into consideration. Normal operating temp is 0.550V, and the low speed fan mode needs to kick in at around 0.5-0.51V. So it is a bit tricky when you get voltage fluctuations from various items activating. When the fans kick in on high speed it also tends to have a major affect on the battery voltage at idle ( no surprise there really! )

A quick test drive this morning showed a big improvement with my wiring changes, but it will be a work in progress for a while. Worst case I'll revert to a different control system. The fans are more than capable of doing the cooling which is the important part.

There's a detailed thread on the build up here: http://www.suzuki-forums.com/suzuki-vit ... o-fan.html

[lokka]

I had the twin AU fans in my rangie they lasted about 3 months they didnt have sealed motors and muddy water killed them

Fitted a 16in davies craig it lasted 7 months it was advertised as a sealed motor and it wasent after a phone call to davies craig i found out that the 16in is the only one they do which isnt sealed and was sent a new 14in to replace it its fully sealed so will see how it goes ive also fitted up a 12in on the out side of the rad to assist the 14in on the inside seems to work well and swiches via the adjustable davies craig switch

[murcod]

http://findarticles.com/p/articles/mi_m ... i_57044400

The above article is worth a read for anyone debating the worth of converting to electric fans.

[hilux_bondy_007]

hey guys i an in brisbane and need to change my thermo so its set to 95 where in brisbane can i get the guage from?

[suzisj40]

i converted to a thermo fan from a belt driven fan because it was getting to hot 4wdriving at low revs and it is still getting hot so can any one recomend putting one on the front or go bac to belt.....

[chimpboy]

i converted to a thermo fan from a belt driven fan because it was getting to hot 4wdriving at low revs and it is still getting hot so can any one recomend putting one on the front or go bac to belt.....

Electric on the front of the rad, and put the belt-driven one back on as well for max fan power I guess.

But... I would also look at other parts of the cooling system, if you have a clogged up radiator or your water pump is on the way out then that would cause problems too.

[dank]

I can recommend the Spal dual 11" fans- they're doing a fantastic job on my Suzuki XL-7 in 46 degree heat. They also make 12" duals as well, but once again they were too big for my core. http://www.spal-usa.com/fans/automated/" onclick="window.open(this.href);return false; ... 102130.pdf

The only issue will be the price, I bought mine from the USA when the exchange rate was 0.96.

The Spal's are not much more expensive than the Davies Craig when the exchange rate is good.

i've got two of these http://www.spalusa.com/pdf/30100411_SPEC.PDF#view=FitH" onclick="window.open(this.href);return false; running on my XJ Radiator mounted in the back of the zook. They are fantastic and i cannot fault their performance. it was a bit of work to get the whole system running but it is amazingly better for my 20v 4age than any front mountable rad I could fit in...and...no mud clogged radiator.

[stuee]

That is pretty impressive making the rear-mounted radiator part of the rear door (tailgate) Very original idea (well first I've seen of it anyway )

[PLAU]

SPAL all the way for me.

I have another car that I use for track work and I compared the Davies Craig to the Spal.

Spal was recommended to me by someone else and I thought to myself, I have never heard of these junk..

Did a lot of research and for my application, the SPAL USA fans moved a lot more air and had less of a pressure drop when car is moving etc (if you know what I mean - this was needed for my application) and were not much difference in price. Who cares about price when your talking cooling though IMO

The only draw back is they drain (my one anyway 16 inch skew blade) a fair bit more current then the Davies Craig but you cant have the best of both worlds I guess.

For other reasons as well, I upped my alternator and batteries like most would do here anyway so power drain wasnt an issue for me.

My single 16 inch SPAL pull moves 3000 CFM (the Davies Craig 16 inch does 2120 CFM) (they may have changed in the last few months but I doubt it so correct me if I am wrong)

The dual 12 inch pull SPALS move 3168 CFM

The dual 11 inch pull SPALS move 2780 CFM

Youc an also add a SPAL Programmable Electric Fan Controller which allows a single SPAL electric fan to vary in speed and temperature. This is to help with fan life and noise. This unit works off of your existing temperature sensor if you wish.

SPAL all the way for me.

This website has a lot of info. If you click on the fan, it will give you the asmps and CFM etc. Remember there are different blades which pull more so check them all out.
http://www.the-fan-man.com/shop/spal-el ... =1&sort=2a" onclick="window.open(this.href);return false;

Another thing many people forget is a Thermo fan has advantages but also disadvantages.

Thermo fans will never move as much as a good old clutch fan with shroud. Never.

In most circumstances a thermo fan is fine but in extreme conditions, I always reccommend to also add a decent engine oil cooler like PWR with fan. People often forget that engine oil counts for a decent amount of cooling - more then you would think. Some quote as much as 20% cooling is done by engine oil. All I know for sure is when I put an oil cooler in, the temp dropped a few degress again. And its not expensive.

Phil

[Blythe]

Hi guys - this is my first post here.

I have just fitted an AU fan assembly to my 94 disco which has a 4.6 RR motor in it - gets up to running temp much faster, fine on the flat, fine on undulating hills and fine in the city but on long uphill runs it gets hotter than with the original. never got above 85 with the viscous fan (viscous frozen which is why I have replaced it) but going up the M1 out of Adelaide yesterday it hit 95c

I am using a TM2 to control it via an external relay. Love the TM2 very accurate, not sure about the AU fans though. I am going to fit fatter wire to it (6mm2) to make sure the juice is getting through ok as I fitted it with 3mm2 since that was all I had but I think I have an unacceptable voltage drop, which I haven't actually measured yet.

Blythe

[stuee]

Hi guys - this is my first post here.

I have just fitted an AU fan assembly to my 94 disco which has a 4.6 RR motor in it - gets up to running temp much faster, fine on the flat, fine on undulating hills and fine in the city but on long uphill runs it gets hotter than with the original. never got above 85 with the viscous fan (viscous frozen which is why I have replaced it) but going up the M1 out of Adelaide yesterday it hit 95c

I am using a TM2 to control it via an external relay. Love the TM2 very accurate, not sure about the AU fans though. I am going to fit fatter wire to it (6mm2) to make sure the juice is getting through ok as I fitted it with 3mm2 since that was all I had but I think I have an unacceptable voltage drop, which I haven't actually measured yet.

Blythe

As far as I know the EFI operating temp of the rover motors is around 87 degrees anyway (82 for a carby). My disco (97 3.9v8) regularly reaches 95 as I have the switch set to come on around this time and cool down to around 90 as if you go below the operating temp it can mess with your fuel consumption.