Electric Fan Installation
Posted By : Philip Wright, 27-Nov-2004, 08:28pm
I am trying to upload a picture, but seem to be having teething problems! Watch this space folks!
Electric Fan Installation
Posted By : Philip Wright, 01-Dec-2004, 12:46pm
Better late than never! The silver thing in the bottom rad hose is the temperature switch - and no leaks!!!
Phil
Phil
Electric Fan Installation
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Electric Fan Installation
Posted By : Paul Bennett, 19-Jan-2006, 01:38pm
I'm about to fit an electric fan and rather then the conventional kenlowe fitted on the outside blowing;
I wondered if it might be better to attempt to fit on the engine side and suck air through as shown here.
As a follow-up I wondered if this was successful and has anyone else tried this method?
Thanks.-
Electric Fan Installation
Posted By : William Davies, 19-Jan-2006, 02:24pm
Aftermarket fans are best situated on the back of the radiator, front mounting should only be done as a last resort when there is insufficient clearance at the back. While many modern cars are equipped with front mounted fans as standard, these are invariably in combination with properly designed ducting to ensure airflow through the radiator.
The pictured vehicle has a 21" radiator fitted, I would not contemplate fitting an electric fan (front or back mounting) with the standard narrow radiator in place,
Cheers,
Bill.-
Electric Fan Installation
Posted By : Ian Osprey, 19-Jan-2006, 03:17pm
Why not with a standard rad then Bill?
Ian-
Electric Fan Installation
Posted By : Neil Nasralla, 19-Jan-2006, 03:47pm
Ian, Bill will probably respond to this but I think the theory is that a fan that either sits in front or behind a standard width radiator actually restricts the air flow through the radiator and reduces cooling. Therefore it is better to have a full width radiator and you probably do not need to run a fan of any kind.
I have a Kenlowe fan that does sit in front of the full width radiator on my Spitfire 1500. The electric fan is rarely needed if at all. I fitted it before I knew all of this (or read others ruminations!) but, as it rarely gets remotely hot I have not bothered changing things.
Ideally the fan sits best behind the radiator pulling air through and you can remove the fixed fan as it just wastes engine power. If you have no overheating problems with a full width radiator then maybe just go with no fan at all?!
cheers, Neil-
Electric Fan Installation
Posted By : William Davies, 19-Jan-2006, 04:13pm
Neil's pretty much covered the theory on airflow being restricted by the fan body. Measure the area of the radiator's face, then see what percentage of that would be obstructed by the imobile body of the fan. That will illustrate in simple terms what kind of negative rather than positive effect an electric fan will have with the small radiator.
I've never been brave enough to run an engine without any fan, though in the vast majority of driving it should be fine. Stationary or slow moving traffic at the height of summer would fill me with fear! The advantage of an electric fan over a fixed type is the fact that it is only placing a load on the engine when required. The electric fan does not completely remove the load, when running it will draw electricity from the alternator, which in turn uses horsepower from the engine. There may or may not be a real world saving in lost bhp. Though the electric fan is likely to be more efficient, there are additional conversion losses to be considered, as mechanical (engine) energy is converted to electrical (alternator) eergy, then back to mechanical (fan) energy. I really can't be that bothered to try applying any maths to this, I will leave that to the people who are trying to eke the last drop of power from their engines - I have enough trouble trying to maintain our one roadworthy Triumph!
Cheers,
Bill. -
Electric Fan Installation
Posted By : Ian Osprey, 19-Jan-2006, 04:14pm
Thanks Neil
I speak from no knowledge of aerodynamics, only the limits on my imagination, and I'm not convinced.
I follow the logic, but feel it's not complete. I'm off to read up on the previous threads before I go off on a rant thet's been covered before.
Bill, just seen your reply, thanks.
I follow the point about he fan's mass in front of the radiator, but when fitted behind, I just can't see that it's significant. As I say, I'll go and read it up.
You both, of course, understand that this is written by someone trying to justify having bought an electric fan?
)
Ian-
Electric Fan Installation
Posted By : Neil Nasralla, 19-Jan-2006, 04:32pm
Ian, when your car is zipping along with nice coolish air flowing straight through the radiator you don't need a fan to assist in any way. In fact an electric fan will probably not be on as the radiator will be getting cooled by the airflow. If you have the narrow radiator and an electric fan in front of it you will get some restriction of the cooling.
When stationary (at the lights etc) after a good run the coolant will warm up and you have no airflow so the electric fan may need to come on. If you have a fixed fan then you will get little air flow just when you need it as the car is idling hence the fixed fan is going slowly and shifting little air through the radiator. This means that the fixed fans are a little pointless. When you are going 70 along the motorway they are not needed but are spinning very fast. When you need them most, they do very little.
Electric fans are far better as they come on when they are needed. The thing is, if installed incorrectly they can restrict the normal air flow you get from forward motion thus requiring the electric fan to come on when it might not have been required.
I found two of the best things that I ever did were to fit an oil cooler - reduced the average temperature of the engine a little bit. The other was to move the number plate so that it did not restrict air flow through the radiator as the number plate normally sits right in front of the grille ona Spitfire 1500. My car used to sit at half way and move up and down from that point. Now it sits just above quarter on the temperature scale never reaching half way. Engine and radiator cowls are also a good idea to help channel the air flow.
best of luck, Neil-
Electric Fan Installation
Posted By : Chris Taylor, 20-Jan-2006, 07:36pm
You want to install whatever fan in the position it was designed to be fitted (and that includes Kenlowe's etc). Fan blades are designed to "suck" or "blow" and while they will do the opposite if turned in the opposite direction, they will not do it as efficiently.
While I have heard the better from behind argument before, I don't really buy it as the same area is obstructing the airflow, whether it is upstream or downstream of the radiator.
On a Spitfire, you want to make sure you have some side valance panels in situ that channel air from the front grill to the radiator. It's not so much the ram effect they have, but more that they prevent the air flow from "spilling" out around the radiator rather than through it. A fan body and brackets "upwind" of the radiator will tend to increase the tendency for air flow to be deflected around the radiator rather than pass through it.
If you don't remove the engine driven fan when you fit the electric fan, then you have simply wasted your money, both in terms of any fuel economy and quieter running. If you need both fans, then you have a problem with your cooling system!-
Electric Fan Installation
Posted By : Andy Cook, 20-Jan-2006, 10:53pm
I've had both arrangements with my GT6, I used to have a Kenlowe fitted in front of the radiator but when it packed up I bought a Pacet fan kit from James Paddock Triumph on their stand at Stafford a few years ago, mainly becuase it was much cheaper then the Kenlowe varieties being sold that year by the likes of Rimmers and Moss.
In my experience the current Pacet fan fitted behind the radiator on my GT6 is much more efficient at cooling the car. I don't know however whether this is because it's behind the radiator or whether the Pacet is just a better fan. It certainly looks much better quality than the Kenlowe as it has a much neater mounting arrangement and a very neat shroud system unlike the Kenlowe which with it's aluminium rod brackets loooks a bit of a bodge to me. I know that Pacet fans are also fitted to quite a few modern cars as OEM unlike Kenlowes which seem to be purely an after market bolt on goodie so I'd reckon on the Pacet set up being a better bet. And of course it's cheaper.....
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