Because the SEiGHT uses a small radiator with a high power engine, cooling problems are not unheard of. However if everything is set up properly then the standard cooling arrangements should be fine for all but the most powerful cars.
Early cars use the 4 row copper cored radiator. This rad has 14 fins per inch, the core measures 14" by 16" and it is 2 3/4" thick. This radiator leans back at an angle inside the nosecone. Later cars use
the 'ducted nosecone' arrangement. The ducted nosecone houses a 5 row aluminium
radiator which is substantially smaller with a core about 11" by 14". The radiator sits vertically. Air is ducted through the radiator and out of the nosecone
just in front of the bonnet. The exit is shaped to help pull air out. All of the air entering the nosecone is forced through the rad and no hot air enters the engine bay.
Although Autocar had cooling problems with a 270HP car using the ducted
nosecone a friend of mine had a 260HP car that was regularly used for track
days and he had no problems. If your engine produces significantly more than 300HP you may need to have a bigger, thicker radiator made up. John Eales does this for customers with very powerful engines.
A word of warning before starting a series of modifications and expenditure - check the accuracy of your temperature gauge. The VDO instruments supplied by Westfield are not particularly accurate. Check the gauge by undoing the sender, running a wire to earth from the sender body, and immersing the sender in boiling water (an electric kettle is good for this). In my experience a good mechanical gauge, such as those supplied by Racetech, is better.
Here are a few modifications which you
can make to improve the cooling if you have the 4 core non-ducted radiator:
- Cut away the inner lip of the nosecone which supports the radiator grill.
Leave four little tags to attach the grill. The piece of fibreglass that
you cut away might look small, but if you work out the surface area you will
see that you are increasing the size of the nosecone opening by 25%.
- Make a duct for the front of the radiator so that as much air as possible
is forced through the radiator and not allowed to spill over the sides of
the rad. This ducting can be made from aluminium sheet. Because the rad
is tipped backwards you only need a duct on the top and the two sides. The 2
side pieces can be rivetted onto the radiator sides and the top piece rivetted
onto the two side sections.
- Use a rear mounted radiator fan as they are more efficient than a front
mounted unit (a front mounted unit blocks off a substantial area of the radiator which lowers the efficiency when you are relying on forward motion pushing air through the rad). The standard Westfield supplied fan is not brilliant and can be replaced with the largest electric fan you can fit.
- Cut out some holes at the back of the bonnet to help hot air to escape
from the engine bay. Some people cut these on the sides
and others cut them on the top. If you have a windscreen be aware that there is a high pressure area in front of the screen that extends most of the way to the front of the bonnet at speed. Therefore any holes you cut in the top will only be effective at low speeds or when the car is stationary. Side holes do not suffer from this and they help prevent water
from getting onto the coil and fuses.
Here are some tips that benefit the old style radiator and the ducted
- Most important of all is to make sure that your engine is tuned properly. Ignition timing is particulary important. A fast road cam that is used with the standard timing will elevate water and exhaust temperatures considerably. As an example, optimizing the idle timing on a 4.2 using a Crane 218 cam reduced the coolant temperature by 12C and the exhaust manifolds by 130C on my car. Before this the cooling system could not cope in a traffic jam on a hot day. For more information on this see the ignition tips.
- In order to allow air locks to escape from the engine and collect in the
header tank you must have good flow through the header tank. The base of the
header tank is connected to the water pump inlet and the small connection
from the header tank should be connected to the highest point of the
cooling system, usually the top hose. When the engine is running you
should see a steady flow of coolant into the header tank through the small
connection. If there is no flow and the water level in the tank rises
significantly when the engine is hot then you have a problem. Effectively
you are pushing air out of the header tank and into the rest of the system
through the bleed hose. This is a common problem if the heater is plumbed
in permanently and the T-piece is connected in such a way that it is easier
to draw water through the heater matrix than the header tank.
- Use a coolant with good heat conducting properties. Plain water has
a higher specific heat capacity than water/anti-freeze (14% better than a 35% mix) but you need something to prevent corrosion in this all-alloy engine. If you run a
low concentration of anti-freeze (e.g. 20%) you will improve the heat
transfer capacity of your coolant while still protecting the engine. Alternatively use plain water with a corrosion inhibitor for maximum cooling. Remember to put the anti-freeze back in the winter...
- Redline Water Wetter is supposed to further improve the heat transfer
capacity of the coolant. Most people find the difference is marginal but any improvement is better than none at all. Incidentally Water Wetter contains the necessary corrosion inhibitors to let you run plain water.
- Always use a thermostat if possible. Engines that have no stat often seem to suffer from
a rapidly fluctuating temperature. They also take a very long time to warm up
in cold weather. If you must run without a stat you should at least use a
restrictor in the thermostat housing so that the water flow through the block
is slowed down a bit. You can make a restrictor by taking the centre out of
an old stat.
- Make sure your system has no leaks and that your expansion tank cap is effective. There are two caps available from Ford dealers for the plastic tank that Westfield use - one is 15psi and the other is only about 10psi. Use the higher rated one.
- Most V8s are fitted with a heater. The water pump forces water into the
front of the block. The water travels to the back of the block before flowing
up into the heads. It then travels along the heads and up into the inlet
manifold at the front of the heads. Most of the water flows out of the
thermostat housing and through the radiator. Some of the water flows out
of the back of the manifold, through the heater core, and back into the water
pump. If you don't have a heater valve then you are effectively recirculating some
hot water straight into the engine. To ensure that all the water from the
engine flows through the radiator you can fit a heater valve to stop water
going through the heater matrix or remove the heater altogether and
block the water outlet at the back of the manifold.
A great web site for technical information on cooling is Stewart Components.
© Ian Crocker
Last updated on July 28th 1999