Best ways to keep an engine cool


Staff member
Deal, Kent UK
A3 1.4 TFSI 150 COD
If you were having trouble with high engine temps after tuning an engine what would be the best ways to keep engine temps low.

Would an oil cooler/larger radiator help much? Does the Coolant fluid mix and type really make that much difference? What about things like wrapping the exhaust and increasing the airflow around the engine bay?
Depends on the state of tune :-)

A remap or intake and exhaust mods shouldn't need any changes to the cooling system. If the engine is running hot it is more likely to be either an air blockage, faulty thermostat or incorrect ignition timing.

Major mods resulting in a fiar increase in BHP may require additional cooling, but only to deal with the extra heat generated when using this extra power. If you don't use it for long periods you may not need to do anything as standard systems have a fair amount of spare capacity.

I don't think that wrapping the exhaust will have much effect on internal engine temperatures, but I am prepared to be corrected on this :-)

Ways to improve cooling:

Change standard radiator for a more efficient one.

If not fitted with an electric fan, fit one (on engine side of rad). For a proper job, also fit a shrould that covers the area of the radiator not covered by the fan. This improves efficiency and cooling as the fan pulls all of the air through the rad rather then just that that is in front of the blades.

Don't overdo the glycol antifreeze. Straight water conducts 140% more heat than glycol, and 60% more heat than a 50/50 mix.

Make sure radiator hoses are not kinked or collapse when hot.

Look at ways of improving the escape routes for hot air out of the engine bay (this isn't as easy as it first looks, as you need to know where the high and low pressure areas are in order to do it properly)

I am sure people can add to this short list :-)

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i think the OP is talking about excessive heat as in when the needle starts to rise above normal running temperature rather than trying to keep it below that line.

the advice i was given was an oil cooler although allowing heat to escape would probably help. the engine is surrounded by metal so heat will be trapped around the engine. as already stated, a better radiator supposedly helps. my radiator is behind an intercooler and air con radiator so it is pretty restricted. it has 2 fans but one is for the A/C but someone has offered me a thicker aluminium radiator which has wider fins and 2 fans which both work for the radiator. the only reason i am considering it is because he will struggle to sell it as the radiator only fits a manual and the vast majority of these cars are autos
In some engines under high load the temps can just run away. This is a problem on track days and even the drag strip.

I've heard that electric water pumps can also help but I'm dubious this will make much of a difference.
I've heard that electric water pumps can also help but I'm dubious this will make much of a difference.

They can help and you can leave them on with the engine off. They release a little extra power as you are not using the engine to drive the pump.

Good for race cars but a little unreliable for full time use, IMO
If the cooling system is capable of maintaining the required temperature then using a cooler opening 'stat' will simply slow down the engine warm up process
I wonder if changing the thermostat for one that opens earlier will help a little more.

Now this rings a bell from my old Cortina MK1 & MK2 days :embarrest:
The heaters on these cars were terrible as they would take ages before they started to produce any heat. Then someone suggested changing the thermostat to one with a lower temperature set point, this worked a treat, if memory serves me correctly, it reduced the heat output waiting time by several minutes.
But the engine would take longer to get to operating temperature, thereby reducing fuel effeciency and increasing engine wear.

However, back then, fuel was never an issue and engines didn't last very long anyway :-)

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