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| Cooling System Diagram Cosworth Cooling Systems Why do GGR produce a replacement high pressure cooling system? What does the swirl pot do? What are the advantages of the aluminium header tank? Do I have to fit the complete high pressure cooling system? Why do GGR only use external oil coolers in extreme circumstances? My water radiator has changed shape, expanding outwards in the middle, will the stronger aluminium radiator prevent this? Why do I have to use anti-freeze, even in the summer? If the cooling system is so efficient, why is it recommended to leave the engine idling for a while before switching off? |
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The cooling system specification is principally identical on every model of the Cosworth range. An aluminium cored radiator with plastic end tanks, cools the water, and this is fed by a plastic expansion tank. The thermostat housing used on the two wheel drive cars differs slightly from the one used on RS 500 and 4 wheel drive engines. When the RS 500 was designed, one of the many detail improvements that was made was a small alteration to the thermostat housing. This altered design allows the water to circulate around the cylinderhead before the thermostat opens. The 4 wheel drive engines use a mass produced version of the RS 500 housing. | |
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| Why do GGR produce a replacement high pressure cooling system? | |
As can be seen from the above, the standard cooling system has a lot of work to do. If the power of the engine is increased, simple physics tells us that additional heat will also be produced. The GGR system consists of a direct replacement aluminium radiator, fabricated header tank & swirl pot. | |
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| What does the swirl pot do? | |
It is standard race car practice to use a swirl pot in the cooling system. If hot spots in the engine cause localised boiling of the water, small pockets of air will form. Air in the water will reduce the heat transference properties of the cooling system. If correctly positioned & designed, the swirl pot will spin the water around inside it, making any water pockets form in the middle of the water. Percolation will then make this air rise inside the swirl pot, and exit out of the small bleed tube in the top, back to the header tank. | |
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| What are the advantages of the aluminium header tank? | |
The original plastic header tanks distort & crack over a period of time. Also the standard type of pressure cap can reduce in efficiency. As the water heats up it expands, if the cap allows the water out of the tank, the reduced quantity of water in the cooling system is less able to control the temperature of the engine, leading to further expansion, and more water pushed out. Another consideration is that as the pressure within the cooling system rises, so does the boiling point of the cooling water, (school boy physics again), so a higher pressure rating can reduce steam pockets and localised overheating. Being manufactured from aluminium, the tank can also be highly polished, or anodised, and fitted with stainless steel braided hoses, improving the look of the engine compartment. | |
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| Do I have to fit the complete high pressure cooling system? | |
It isn't always necessary to fit the complete system. Many people fit the header tank & swirl pot first, as this has been found to help stabilise fluctuating coolant temperatures, then finally change the radiator. | |
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| Why do GGR only use external oil coolers in extreme circumstances? | |
The heat exchanger system explained above is very efficient. Both bringing the oil up to operating temperature, and then preventing it from overheating. It is therefore more advisable to improve the water cooling system first, and then when conditions dictate, fit an independent oil cooler. | |
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| My water radiator has changed shape, expanding outwards in the middle, will the stronger aluminium radiator prevent this? | |
Changing to the aluminium radiator may cure this problem initially, but it isn't really a radiator problem. The reason that the radiator has ballooned outwards is that the head gasket has started to fail. The radiator has been momentarily overpressured by combustion gasses entering the cooling system. This will only happen initially when the engine is producing high turbo boost, but as the gasket deteriorates, it will happen more frequently. | |
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| Why do I have to use anti-freeze, even in the summer? | |
Good quality anti-freeze must always be used in a Cosworth engine as it has excellent anti-corrosion properties. The water ways inside the aluminium cylinderhead would soon erode away causing water leaks and irreparably damaging the cylinderhead. Corrosion contaminated water does not transfer heat as efficiently as a clean water/anti-freeze mixture. | |
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| If the cooling system is so efficient, why is it recommended to leave the engine idling for a while before switching off? | |
When the engine is driven hard, temperatures within certain parts reach very high levels. The turbocharger and exhaust system temperatures can easily rise to 1000°C. If the engine is turned off immediately in this situation, the heat from the turbocharger will slowly soak into the engine and boil away the stationary cooling water. This will then cause localised overheating, distorting, and softening of parts of the engine. The lubrication oil inside the delicate turbocharger bearings will also overheat and possibly crystallise. When the engine is re-started, the abrasive, crystallised oil will then damage the bearings. If the car has been driven hard, a good practice is to leave it idling until the electric cooling fans on the radiator start and then stop again. This signifies that the heat has been carried away from the hot parts of the engine to the radiator, (causing the fans to start), and then that the complete system temperature has cooled to acceptable levels, (causing the fans to stop). | |
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