Cooling fan

[Echezeaux]

Looking at the factory fitted cooling fan, I often ask myself " What were they thinking ?? "
Here is the factory one next to a Coolcat fan



Parts of the Coolcat system I am fitting to my 3.8


What kind of system do you have on your car ?

[Heuer]

Kenlowe on mine and has been there for 9 years without a problem - they seem the most popular and best developed products in the UK. Never had the car overheat even stuck in traffic in Biarritz when the air temperature was 42c.


Pacet fans also seem to be used by the performance and racing crowd (Caterhams, Cobra's etc) http://www.pacet.co.uk/

[Peter B.]

Hello,
last year I fitted a Kenlowe, after my old one broke during an oldtimer rallye with +30 degreees C..... Fortunately no further damage. Since then I had no more heat-related issues. A product I can advice to buy.
Kind regards
Peter

[daverawle]

Looking at the factory fitted cooling fan, I often ask myself " What were they thinking ?? "
Here is the factory one next to a Coolcat fan

What kind of system do you have on your car ?

This one from Derek Watson works very well.....


Dave

[Moeregaard]

I like the CoolCat fan. It's extremely effective and utilizes the factory mount. I absolutely hate aftermarket fans that strap to the radiator matrix.

As an interesting (or not) aside, when I was forced to use one of the aforementioned "strap-on" fans, I found that leaving the fan shroud in place actually caused temperatures to rise.

My theory is that the shroud is only effective when the fan blades are in plane with its opening, thereby creating the necessary pressure drop across the back side of the radiator that draws air through the entire matrix.

[daverawle]

I absolutely hate aftermarket fans that strap to the radiator matrix.

I'm with you on fans that fit to the radiator core, don't like them. But I have another question; What happens to the air flow when the multi bladed fan is off? If it turns/windmills then the radiator is on the lea-side, so not getting the best of the rammed-air and brushes and bearings are still being used. Okay, it sounds petty but I recently connected a meter to my fan motor and drove at 40 mph - I was getting over 12 volts!

I'm considering fitting a fan relay that shorts the motor when the fan is not operative in the hope that it will stop it windmilling. I'll let the list know how it goes.

Dave

[Heuer]

I have to fess up here to say my Kenlowe is zip strapped to the (Cambridge Motorsport) alloy radiator. We were on the E-Type 50th trip to Geneva when our car started to overheat in the back streets of Beaune. Spoke to Kenlowe and they had a fan sent overnight to our next stop. It was installed in the car park of a Hotel using zip ties as recommended. I always worried about that but even CMC (who this year took the engine out) could not find fault with it. So eight years on, aluminium rad, and the fan is still well mounted and effective. Clearly Hotel car parks have a lot to commend themselves!

[kingzetts]

Dave, I'd have thought that the only ways to stop an electric fan from windmilling would either be to apply a mechanical brake, or to apply reverse voltage to cause the motor to oppose the air flow. Surely shorting the motor will simply ensure that the fan will windmill but will prevent any current being drawn off into the car's electrics.

I'd also imagine that a windmilling fan with no current being drawn will generate less drag than a fan held in a fixed position. It may be generating 12V (which you'd expect) but the drag will be minimal unless current is being drawn. A simple way to prevent current draw would be to install a diode in the feed wire to the fan motor, although it would have to be able to handle the current draw of the motor when running.

Whether the fan is in front of or behind the radiator won't much matter, I think. Its the ducting to the radiator which will most influence ram air feed, and the fan shroud behind the radiator (if that's where the fan sits) is mainly to ensure the fan draws air through the matrix most effectively when it is actually working.

[daverawle]

Hi John,

I?m no expert in this but this is the way I see it: if the fan is stationary the air pressure at both sides will be similar. If the fan is tuning then it is extracting energy from the air flow, therefore the air flow downwind will be reduced.

Shorting the motor will reduce the speed of the fan, but by how much I have yet to determine. Drag isn?t the issue but cooling and wear-and-tear on the fan motor is so I think it?s worth further investigation.

Dave

[Moeregaard]

Dave is correct. A windmilling fan blade typically produces more drag than one that is stationary. The reason for this is that the airflow regards the windmilling blade as a porous disc. In a perfect world we would be able to feather the blades when the fan is not in use. Since airflow at cruising speeds is more than adequate for cooling purposes, the rotating fan blades behind the radiator don't present much of a problem.

[Heuer]

I see there is another company making a combined radiator and fan for the S1 - Radtec http://www.radtec.co.uk/ They also make radiators for the S3 and S3.

[MarkE]

I have to ask the dumb question....does the S1 need an aftermarket fan? I can perhaps understand the need in a hot climate, but I've never seen a contemporary test of the S1 that complains of overheating.

It's a genuine question. In my quest for originality (but not at all costs) I've retained the original single fan blade and motor.....should I be looking to upgrade?

[Heuer]

Mark

The E-Type was developed at a time when there were fewer cars on the road. Providing it is on the move there is sufficient air flow to keep the temperature at normal aided by the fan on the (in the 60's) occasional stop for junctions and lights. The standard fan will struggle to keep the temperature down after more than few minutes in stationary traffic on a mild day so in answer to your question, yes, you need to replace the fan if you intend to use the car. The Coolcat fan is probably the best as it easily replaces the existing motor/fan blade without modification. Worth getting the associated Coolcat otter switch at the same time. Add a bottle of Water Wetter for extra security.

Trust me on this - there is nothing worse than being stuck in traffic and watching the gauge steadily climb into the red!

[kingzetts]

I disagree with both Moe and Dave on this fan windmilling issue.

For a given motorised fan sitting in still air, assuming a fixed blade angle (no feathering, Moe), the amount if induced air flow will increase as the speed of the fan increases, and the power required to drive the fan will also increase.

If the same fan is sitting in a moving stream of air, and is used to turn a generator, the fan will turn more slowly as the power drawn from the generator is increased until the point is reached where the fan is about to stall. It follows from this that the drag forces created by a stalled fan are higher than the drag forces imposed by a freely windmilling fan.

Anyway, the key point is that none of this really matters as airflow at speed is, as Moe observed, more than adequate for cooling so any drag caused by the fan (whether stationary or windmilling) is of only academic interest.

[MarkE]

John?s tilting at Windmills now?..

David, I agree there?s nothing worse that watching the needle going into the red, but it?s never happened to me in the UK in London traffic or heavy motorway traffic in an old car. Stupidly, I had a Dolomite Sprint then a Daimler Double Six when I lived in Australia, and in 40 degrees in the city, having the heater on full blast isn?t much fun at all! Should have bought a Holden.

My S1 lived in Los Angeles for the 9 years it was on the road?how did it cope with that? None of the American tests from the 60s that I have read say what a great car it would be if only it didn?t overheat all the time. I have a suspicion that a lot of the overheating problems of old cars in modern traffic conditions is down to knackered and bunged up radiators and silted up blocks. The amount of rubbish that came out of my block when we acid-cleaned it was alarming! When the liners came out of the V12, nearly a bucket full of sandy scale was retrieved.

There were traffic jams in the 60s and 70s as well due to there being very few dual carriageways / motorways. I well remember being stuck in the back of a car in the period getting very bored with not moving at all for what seemed like hours. OK. they?re an everyday occurrence now in many built up places, but I?m not commuting in and out of a city everyday in the car?or sitting on the M25 car park.

It?s a standard response with the Lotus folks as well?got to have a new aluminium radiator with double electric fans and water wetter and a swirl pot and a top filler?... I still use the standard set up?an Anglia fan blade on the water pump and standard radiator, and whilst it gets hot in traffic, it doesn?t overheat. I guess that?s why I ask the question?is everyone doing it because everyone is doing it, or is it really needed on a car that is running as it should be? I guess I will find out!!

Is anybody out there running the standard set up in a S1?

[daverawle]

I disagree with both Moe and Dave on this fan windmilling issue.

It's a thought inducing subject - I like dynamic stuff :-)

If the wind speed was not decreased by the fan then wind-farms could be built in a row, but they aren't. Sail boats keep away from each other for the same reason, the fan is just another form of sail.

Anyway, in an E-Type the biggest fan wins given that traffic flow is a bigger factor than air-flow nowadays.

Dave

[Peter B.]

Marc,

my old fan broke on a day with temperatures in excess of 30 degrees celsius. As long as I had an open road there was no real prpoblem occuring. But when we approached our target destination we had to slow down and some stop and go before entering the final parking lot. It wasn?t for more than 10 minutes, but it made my cooling boil. The day before I was caught in a jam on the autobahn, if it would have broken then, I assume it would have killed my head gasket.
So from my personal view, it gives me a better feeling when using the car in modern traffic conditions.

Kind regards
Peter

[MarkE]

Hi Peter. How was the car before the fan broke...could it cope with traffic and warm days? I have a sneaking suspicion that it probably could, but that, in general, people get mixed up comparing old, tired original components with modern replacements in perfect condition. It seems that many upgrades are justified by owners replacing worn out original components with brand new 'upgraded' parts...and of course, the difference will be very noticeable. But if the old worn out component was replaced with a new or reconditioned component to original specification, the difference would also be considerable.

I'm sure that there will never be a definitive answer to this...it's all down to individual experience. I'll try my original setup, in all conditions, and if the car doesn't perform well, I will upgrade....but only if it is really required.

I guess that my last concern is that of aftermarket components, which I find to be of very poor quality in general. The components in modern cars have to go through stringent temperature, performance, damp and oil contamination tests, but I doubt that the average aftermarket fan motor has to do anything other than work for a while in normal conditions. There seem to be many horror stories with the magic electronic ignition systems, which work well for a couple of years, then seem to mysteriously pack up. When first fitted, the car now ?starts on the button??.well it should do with points and condenser, but again, with a knackered system, the upgrade and original components aren?t being compared like for like.

We?ll see?I may well have to eat my words!!

[Echezeaux]

I must admit that I replaced mine because the factory one was disconnected, and an ugly aftermarket fan had been fitted at the front of the radiator.

As I am trying to make the car reliable before I start to drive it, I thought better safe than sorry.
But like MarkE, I think the car might be OK if the engine block is " clean " BUT.. I remember something about the californian dealers complaining about cars overheathing, and the factory saying that the cars don't overheat in England !!
In my view the Coolcat fan offers the best about performance and original look.

[Peter B.]

Marc,
my car was already equipped with an aftermarket fan, the original one got lost in the streams of time.... The car came from South Africa, so I assume it was necessary down there.
In Germany it worked well, until the fan broke and I had to do some stop?n?go, but there was no engine-driven cooling left at all, so it?s hard to tell for me. When we had an open road, the cooling was sufficient, even without additional fan.
But I live in a quite densed area, with some traffic jam to be expected when on a trip. So I voted for the safe way and replaced the old aftermarket part with a new Kenlowe, and this one works well so far.
Kind Regards
Peter