The desert environment is a tough challenge for engines. Read here to find out...
Coming just a few days after Round 3 of the 2012 FIA Formula One World Championship in Shanghai, Round 4 sees Renault Sport F1 return to Bahrain for the first time since 2010.
The Bahrain International Circuit poses some unique challenges for Renault, not least, as Head of Track Operations Rémi Taffin explains, because of the high temperatures experienced in the Gulf. However, Rémi divulges that by far the greatest engine concern in Bahrain will be not just the heat, but the type of heat experienced:
“There are two main issues with regards to the climate in Bahrain; the heat and the aridity of the desert air. The higher temperatures are of obvious concern as it makes all the systems run very hot and we have to open up the bodywork to make sure nothing overheats. This obviously has an impact on the aerodynamic performance of the car as the tighter the bodywork is to the car, the more efficient it is aerodynamically.
“It puts the emphasis on an engine supplier to make cooling as efficient as possible because, if not, we have to open the bodywork more to make sure that we can cool the engine, gearbox and everything else like KERS.
“Getting the right cooling system is therefore crucial. We try to get the lowest heat rejection into the car cooling system by operating the engine at higher water and oil temperatures, which eventually get the heat rejection down. However this means that the internal engine parts will run at a higher temperature, which needs careful monitoring.
“The second factor for engine engineers to watch is the relative humidity, or lack of relative humidity in the air. The air is so dry and hot that the stress on the engine is very hard. In fact, you can get an engine to ‘detonate’ if it is not managed correctly. This is a very destructive phenomenon; basically it consists in an abnormal combustion of the air and the fuel in the engine. The propagation of the combustion flame is not under control, or predictable, anymore and cylinder pressure would reach destructive levels with subsequently massive stresses on the piston. To prevent this, we tune the ignition timing differently for this race.
“This is done by recreating these dry and hot conditions on the dyno back at Viry and running an engine fitted with cylinder pressure sensors that will help us tracking the signs of detonation. We can clearly pick up detonation through the cylinder pressure when it starts to get very “noisy”, which is the sign of a higher frequency phenomenon. As soon as detonation looks likely we quickly tune the ignition, reducing the timing to eradicate the detonation. This map is then inputted into the ECU to allow the engine to regulate itself.
“We can also tune the engine by varying the length of the trumpets, which regulate the intake of air into the engine via the airbox. It’s actually very similar to tuning an actual instrument – you play around with the air inlets such as the mouthpiece of a trumpet or the reed on a clarinet to make sure that the air hits the keys at the right time. It’s the same for the engine; playing with the length of the trumpets allows the pressure waves to arrive at the inlet valve at the perfect time, therefore inducing more air into the engine and creating more power.
“Under the regulations teams are allowed to homologate three sets of different length inlet trumpets. We will use the longest set here. If you don’t change the trumpets the engine will tune at a higher engine speed, making it peaky for the driver and not great for lap time as the power will be too high up the rev range.”
The high temperatures and low humidity obviously stem from the fact that Sakhir is located in a desert, another cause for concern on account of the large amount of airborne particles in the atmosphere.
“Another concern when we visit a track in the Gulf, like Bahrain, is the level of dust, sand and airborne particles. If the dust gets into the internals it can damage pistons, rings, valve seats and subsequently bearings as the dust is conveyed by the lubricant.
“This would obviously be a real problem, but equally having too intense an air filter stops oxygen getting into the engine, which causes a power loss. There are two ways you can go about this; either trap the particles or evacuate them. To trap them we would need a lot of surface cover but the risk is that the filtering area is then eventually blocked, which would cause a performance drop. We have actually developed a special air filter based on filters pioneered in desert rallying, obviously one of the most difficult environments cars race in.
“Now we feel quite confident going to tracks like Bahrain. The last time we went there we stripped the engines after the race to see how the new measures had worked, and that helped us to move forward as we knew that there was very little dust in the internals. When we compared this with the data of the torque and power, there was very little difference between Bahrain and somewhere less dusty like Silverstone so we knew we had the right compromise.”
“From the layout of the track Bahrain looks easy enough, and in actual fact the strains on the engine over one lap are not that high, but it’s the conditions around the track that make it one of the more interesting circuits engine-wise.”