Beat an Overheating tuned engine

"Keep cool!"

Tuned engines and cars driven hard may experience issues with overheating.

An engine that runs too hot is prone to failure, often the gaskets are the first things to go.


As engine temperatures build up they tend to run away and if you can't keep them under control they quickly rise to critical levels.

For short bursts of power extra cooling is not usually required. For track days and heavily tuned cars you will need to address engine cooling.

Minor modifications like remapping or intake and exhaust mods shouldn't require any changes to the cooling system.

If the engine is running hot it is more likely to be either a coolant blockage, faulty thermostat, failing water pump or incorrect ignition timing or another mechanical fault, rather than something you need to correct through modification.

So before you look at adding cooling measures make sure your standard system is working correctly and as you would expect for the conditions it is operating under. Under light load a fairly standard engine should not overheat.


Major mods resulting in a fair 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. 

It is highly unlikely that wrapping the exhaust will have much effect on internal engine temperatures.

It does help to keep the heat inside the exhaust and lowers the engine bay temperatures a little.  

Ways to improve cooling:

Oil selection can make a big difference. If you compare the cheapest low grade brand available with the highest quality synthetic of the same grade you will notice a difference in engine temperatures.

Synthetic oils maintain their properties for much longer than mineral oils so over time the difference between a quality oil and synthetic one get bigger.

Radiators and cooling system upgrades.

Change the standard radiator for a more efficient one. You can get dual or triple core radiators now so these make sensible upgrade choices. If you have modified the body of the car you need to ensure that enough of the front radiator is exposed to the air or it will not work effectively.

Don't overdo the glycol antifreeze. Straight water conducts 140% more heat than glycol, and 60% more heat than a 50/50 mix. There are also additives which greatly improve the thermal transfer properties of water and these can be beneficial in track cars, although some of these reportedly can cause corrosion of certain metals.

Make sure radiator hoses are not kinked or that they collapse when hot as this will impede the flow of coolant. This is best checked with the engine running.

An electric water pump can also increase the flow rate of coolant around the engine and will offer additional performance benefits.

oil-coolerAn oil cooler also makes sense if you are experiencing overheating.

All the oil is circulated through a radiator which lowers the oil temperatures and aids with engine cooling. You'll need to top up with slightly more oil now as the oil cooler will act as a store for the oil.

If not fitted with an electric fan, fit one if fitted then look to get a higher flowing one (fit this on the engine side of the radiator so it pulls cold air through the radiator). For a proper job, also fit a shroud around the fan to help pull air right through the radiator.

This improves efficiency and cooling as the fan pulls all of the air through the radiator rather then just that that is in front of the blades. Adding a lower temperature sensor to your fan circuit will force the fan to kick in sooner and help prevent heat build up.

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) Adding some vents to the top of the engine bay and at the sides of the arches can help reduce the engine bay temperatures and increase the rate of cold air flow around the engine.

Extreme cooling methods

Spraying nitrous or similar onto the radiator will dramatically cool it, but you will need to manage the delivery of coolant very carefully and will need to recharge the gas bottle or reservoir.

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