In preparation for the 24 Hours of Le Mans, competitors do their best to reproduce the particular racing conditions of the Circuit de la Sarthe. The heat is an important element, which is why many teams travel to Sebring in the USA or Abu Dhabi (UAE) for their training.

But what if, back in 1923, the founders had decided to stage the biggest real-time test of technical prowess during the coldest months of the year? We asked Bruno, World Endurance Championship engineer in chief and a member of the OAK Racing team, to explain what a difference it would have made.

How does temperature affect engine performance? Could a lower temperature be beneficial?
Engines have a temperature range for water (cooling) and oil (lubrification). We try to keep the water temperature down to improve engine performance irrespective of outside temperature. Oil is less sensitive. High temperatures are more problematic than low ones as it is always possible to stop the engine getting too cold with a radiator shroud, whereas cooling it down is more difficult.

But temperature isn’t the only factor?
No. The temperature of the air that enters the motor is important, but it’s not the only factor. You also need to account for atmospheric pressure and humidity. These three factors influence air density. At constant atmospheric pressure and humidity, the lower the temperature, the higher the density – there is more oxygen – which means more power and higher torque due to improved combustion.

Therefore, racing in winter would mean better engine performance. What is the reasonable temperature range for an endurance racing car?
There are more limits on the temperature of the track than on air temperature. As long as the track is driveable, you can run a prototype on it.

What issues would there be with the set-ups?
The issues involve the tyres, which transmit the car’s power to the ground and keep it on the track when braking and turning. On a circuit like Le Mans, we would probably have to develop special tyres for very low track temperatures. The long straights mean the track gets very cold very quickly. Then the suspension would have to be adjusted to suit the tyres.

Would the warm-up have to be longer?
Not really, but there would be more of them if there’s a long stoppage during testing, for example.

In conclusion, are there advantages to racing in winter? Would it be more comfortable for drivers, who get very hot in the cockpit in summer?
Well there would be no more open cockpits, that’s for sure! True, drivers wouldn’t suffer from the heat but draughts, especially around the legs, could be a problem. Other than that, I don’t see any particular advantages for drivers or for their team, for whom cold weather means unpleasant working conditions.

Geoffroy Barre, with thanks to Hélène Dagoreau and Bruno Corbe.

PHOTO: LE MANS (SARTHE, FRANCE), CIRCUIT DES 24 HEURES, LE MANS 24 HOURS, SUNDAY 14 JUNE 2015, RACE. Night stint in Oak Racing’s #34 Ligier JS P2.