Why should I fit rear mounted cooling fans?
When I am attending shows and talking with people about the parts I sell. They regularly ask me why I say that rear mounted fans are more efficient than front mounted fans.
If you take two identical fans one blowing air the other pulling air. They are capable of moving the same amount of air so there should be no difference right? WRONG
Simple example. Lay a piece of rope out on the ground. Take one end and pull it. The rope moves smoothly across the ground
Now take the opposite end of the rope and try pushing it. This time the rope does not move smoothly, instead it starts buckling and starts to snake.
You have used the same amount of force in the same direction but the results are very different (and it’s the same with cooling fans).
A rear mounted cooling fan pulling air through a radiator will perform better than a fan blowing air through it. These are not my words, these are the words of the fan manufacturers and radiator companies. Some quote figures as low as 80% the efficiency of a similar fan pulling air through a radiator. In other words, a front mounted fan could lose you 20% cooling efficiency against a rear mounted fan. (These figures are for extreme cases)
The reason for this is because a puller fan uses the laws of physics to its advantage.
A blowing fan tries to force air through the radiator which acts as a restriction to the air flow causing an increase in pressure at the front of the radiator as some of the air bounces back off it.
A rear mounted pulling fan does not cause a pressure increase, but actually creates a slight drop in air pressure across the radiator. Now if you remember from school physics lessons the various laws regarding gases such as “Boyles Law” etc you know that air pressure, volume and temperature are all interlinked (change one you change the others) so if you drop the air pressure you can change the air volume/ density and also get a slight temperature drop. These can all be very beneficial effects for air flowing through a radiator .
From experience a lot of these effects can be quite subtle but when incorporated together as part of a properly designed cooling kit these tiny differences can add up to a major improvement.
The following information has been gained from many years of owning and working on my Elan. It is designed as a general guide and starting point to help you make a decision about buying an Elan and what to look out for.
It should only form part of your research; further information and resources can be found at the end of this article.
LOTUS = Lots of Trouble Usually Serious???
Buyers. You have decided to buy a Lotus Elan or Plus 2. Good choice – the Elan is still rated as one of the all time great sports cars and the Plus 2 gives the Lotus driving experience with the comfort and practicality of 4 seats.
The problem is your friends have pointed out the old joke:
LOTUS = Lots Of Trouble Usually Serious
Well your friends are only part right. Continue reading >>
“My original 2 core radiator is overheating.
I am going to replace it with an aluminium three core one.
A guy on the internet sells them. He states that the aluminium is better at transferring heat and the extra core gives me 50% more cooling right?”
Continue reading >>
When looking at the figures for how much flow you get with a particular fan, most figures are quoted in either cubic feet per minute (CFM) or metres cubed per hour (m3/hr). The higher the value, the more air the fan is capable of moving.
So when choosing which 10” fan to buy, go for the one with the highest number right?
Not quite that simple.
In order to make the fan look impressive, the value stated is usually the maximum amount of air it can flow (which makes sense). However that figure is usually for the fan at zero static air pressure. Which is the equivalent of hanging the fan in mid air with nothing in front or behind it to restrict the flow.
Which does not really represent what you will do with your fan when you attach it to the radiator. Continue reading >>
A lot is talked about classic car cooling systems and particularly the subject of fitting a better radiator to improve cooling. A simple search of the web will reveal countless replacement radiators all different but all claiming to be the best for keeping your car cool. Buying and fitting an efficient radiator should be fairly straight forward. Unfortunately its not.
I know of owners who have fitted up rated radiators with extra cores only to have it make things worse.
Hopefully this article will explain better how a cooling system actually works and give you the information you need to make an informed decision about improving the cooling system for your car. Continue reading >>