ams Exclusive: Formula 1 against WEC
28.12.2015
G is that even? A marathon runner versus a sprinter. A coupe versus a convertible. Porsche versus Mercedes. At first glance, a Formula 1 car and a sports car for the World Endurance Championship (WEC) have little in common. The Mercedes AMG W06 only serves one purpose. Go around in circles as fast as possible. Without outside help, i.e. external starters, it won't move from the spot. You could also go shopping with the Porsche 919 Hybrid. It has a roof, disguised wheels, headlights, a windshield wiper, a starter and space for shelves in the cockpit. Sounds like a real car.
The requirements do not seem suitable to compare one with the other. The Porsche drives between six and 24 hours straight. A drive unit is designed for 6,000 kilometers. At the Mercedes, the checkered flag falls after two hours at the latest. The engine and gearbox are still cross-country skiers. The best Mercedes engine covered 4,798 kilometers this year. A transmission has to last 3,500 kilometers.
Three drivers take turns in the Porsche. The two Silver Arrows belong to Lewis Hamilton and Nico Rosberg all alone. The Mercedes weighs 701 kilograms with the driver. His fully disguised counterpart, including the mandatory driver weight, weighs 950 kilograms.
Efficiency and downsizing are trumps
Let's not be distracted by the little things. The Mercedes and the Porsche are more similar than it appears. In both cases, hybrid technology is hidden under the carbon fiber skin. It's about efficiency, downsizing and low speeds. The displacements do not sound like great motorsport. Due to the regulations, Mercedes uses a charged 1.6 liter six-cylinder. The rules only stipulate one turbine and one compressor. Porsche had all the freedom and opted for a 2.0-liter V4 biturbo.
Head of Technology Alex Hitzinger explains why: 'Exhaust gas recovery only makes sense with a turbo engine. to keep the weight down. The engine should also be a structural part of the car. That is what the V concept dictates. We had the choice between a V4 and a V6. A V4 has thermodynamic advantages and mechanical disadvantages. '
Porsche had to experience it painfully. The four-cylinder was practically designed twice. When it was first started, the motor vibrated so much thatall parts in the periphery were cut short and small. 'We were too ambitious with the firing order. We just looked at the gas exchange and thought we could manage it. I had to pull the rip cord if we wanted to race in 2014. The new firing order meant a new crankshaft, new camshafts and a new coordination of the gas exchange. That was already a mega number. '
More freedom for WEC engines
In Formula 1, the FIA saved the manufacturers an elaborate thought process, a lot Time and money. The engine's architecture is set in stone. 'What would we have done had we had all the freedom like Porsche?' Asks Mercedes engine boss Andy Cowell the question. 'A V4? Possible. Less than 1.6 liter displacement with a lot of boost? Possible. A twin turbo? It gets more difficult with the packaging in a Formula 1 car. We want to be as slim as possible in the rear. Two Chargers on the outside of the engine limit the shape of the bottle neck. '
The turbo engines are each accompanied by two electric machines. One draws its juice from kinetic energy and is called MGU-K. The other is fed from exhaust gas recovery. In principle, the MGU-H (Formula 1) and the AER (WEC) do the same. They use the thermal expansion of the exhaust gases, which are not used to build up the boost pressure. The difference is in the use. And that is determined by the regulations. A Formula 1 car may not draw more than four MegaJoules of energy from the battery per lap, but never more than 163 hp at a time. The long-distance racer is free to use his energy.
This results in decisive differences in energy management. Formula 1 distributes its 120 kilowatts nicely over the lap. With the exception of the spa, the storage tank is always filled so that the electric power lasts for the entire circuit. Porsche mainly lets its electric thrust off the chain when accelerating.
Andy Cowell explains why: 'The lap time is determined by the speed at the apex and corner exit, not how fast you enter the corner. That's why you want the maximum Power for the first third of the straight. If you take off the accelerator for the last two thirds, the lap time hurts less. If Porsche were to give the whole straight an electric boost, they'd have to give something when accelerating. That would be less fast. We are restricted by the 120 kilowatt rule. That's why we distribute the power differently. We make sure that the combustion engine delivers as much power as possible and then boosts over the straight as long as we have the electrical power available. And it is there. '
Le Mans winner Porsche is estimated at 1,350 hp
How much electrical power Porsche can mobilize when accelerating remains a secret. At least 500 hp, if you can believe the Porsche brochure. 850 hp if you take the measurements of the competitionbe right. Together with the V4 biturbo, which delivers around 530 hp at 9,000 rpm, this would result in a system output of around 1,350 hp. The 850 hp of the Formula 1 engine look rather harmless.
Not the end of the flagpole for Cowell. 'All manufacturers started in 2014 with horsepower figures that they thought impossible at the beginning of development two years ago. Each of us has improved in the last 18 months. I was surprised at the increase we achieved during this time. I hope that I will still be surprised after the next 18 months. Is a jump of 200 hp possible in ten years? Why not. ' Engine and gasoline development go hand in hand. While Mercedes partner Petronas has a free hand, nothing beats fuel at Porsche. 'We drive standard petrol from Shell,' explains Hitzinger.
The GPS data confirms what Le Mans winner Nico Hülkenberg describes: 'You drive the Porsche in a rather V-shaped way through the corners, especially out of slow corners because you always want to hit the gas 100 percent as early as possible. ' The Porsche therefore has its apex between 20 and 40 meters earlier. When the Mercedes reaches its slowest speed, the Porsche driver is back on the gas. Sometimes it takes 200 meters for Formula 1 to catch up again. Despite its weight advantage of 250 kilograms.
Mercedes with all-wheel drive three seconds faster
In Formula 1, the Flow rate of 100 kilograms per hour at any time and at any distance. If the Mercedes saves fuel in one lap, it can use up the reserve in the next lap. But he practically always has it. Even on the straight, when the Porsche has long been operating 'lift and coast' again in order to fill the memory with a maximum of eight MegaJoules and save fuel. This is not available to the sports car as generously as its brother from the premier class.
The WEC-Porsche doesn't get anything back. Fixed rates apply to him depending on the route. 96.9 kilograms per hour. If he stays under, it's your own fault. That is why one cannot afford a luxury like 'overloading' the engine at Porsche. Formula 1 also recuperates kinetically when accelerating, because the MGU-K fights against the excess torque that cannot be brought onto the road. To do this, more gasoline is injected when accelerating on low-consumption routes than is actually necessary. 'That doesn't make sense for us,' regrets Hitzinger.
He has fewer problems with traction. The Porsche 919 is an all-wheel drive car and has traction control. The MGU-K gives off its power via the front wheels. Mercedes technical director Paddy Lowe estimates: 'With traction control and all-wheel drive, we could gain three seconds per lap.'
What the Mercedes cannot recuperate with the MGU-Khe has to top up with the MGU-H. It mainly functions as a generator to fill the turbo lag, but it can store energy in the battery as well as deliver it directly via the MGU-K. And unlimited. But this energy is not free. It creates back pressure in the exhaust system and costs the combustion engine power.
Porsche has ingeniously solved this problem thanks to its biturbo. The AER delivers electricity at full load without the four-cylinder suffering from it, as Hitzinger explains: 'In Formula 1 you drive with an electric turbocharger. You have a turbine that is connected to the compressor by a shaft and you have an electric machine, ideally between the turbine and compressor. We have a normal turbocharger and a second turbine in parallel. And that drives an electric generator. We control this turbine via a VTG that replaces the wastegate. It determines how much boost pressure the first compressor gets and how much is branched off for charging. The two turbines are spatially separated from each other. This means that there is no power loss in the combustion engine when charging the MGU-H. Our system has a second advantage. If the MGU-H no longer works, the turbo engine drives separately turn on the car. In a 24-hour race, that can save you the race. In Formula 1, you don't drive a meter anymore. '
The Porsche 919 is a Formula 1 with a roof
Both cars fit well in a double garage. The Mercedes is 30 centimeters longer, but 10 centimeters narrower and 10 centimeters lower. In return, the Porsche enjoys aerodynamic advantages due to its architecture. Covered wheels and a roof over your head improve the ratio of drag to downforce by 20 to 30 percent.
The standard corset is equally tight in both cases. Formula 1 technology is defined on 88 pages, the WEC on 72. 'The diffuser is completely regulated. There are footwell templates for the driver, for the view to the front and to the side. You build so small around them as possible your monocoque. With the rear wing there are boxes in which the wing must move. In addition, a fin on the engine cover, which is the rule. With the rear wheel arches you are very limited with the cutouts. The task is to control the airflow to direct predefined holes around so that the damage is as little as possible, 'explains Hitzinger.
In principle, Formula 1 develops according to the same principle. Converting turbulent air into good air. Use wake vortices as a weapon against other air vortices. His colleague Paddy Lowe has long since got used to the restrictions. 'Are the rules too complicated, too restrictive? I don't think so. Half of the rules concern safety. They have to be. The complexity comes from the fact that a well-intentioned rule is torpedoed by engineers with clever ideas. So it has to be rewritten. That makes them complicated. '
SinceIn 2009 the downforce was reduced so that the engineers can practically concentrate on an aero configuration. Lowe: 'We have to pay much less attention to these extreme races than before. The downforce is now so low that we are almost everywhere with Monte Carlo downforce. Except for Monza and Spa. On the other tracks you are out with maximum downforce or very close to it. '
Mercedes took two years of development time
In the WEC, Le Mans will definitely do Development roadmap. Porsche drove the first two races in the Le Mans trim to practice for the classic. The victories given away to Audi were tolerated. Porsche won Le Mans and then built an aero kit for the rest of the season. And won there too. In the end, the two cars are not that different, as Hitzinger says: 'In principle, we have a Formula 1 chassis with a roof. Our tasks are very similar to those in Formula 1, except that we are mainly concerned with low air resistance goes. '
The 2015 model of the 919 Hybrid is already the second infusion. A completely new design that lost 30 kilograms compared to the previous year. The Mercedes was nine kilograms heavier. The regulations required it. The current Mercedes is more of an evolution than a revolution. Because the task was so big the year before. 'It was a big project,' says Lowe, looking back. Much work had to start very early because it required a completely new concept, a completely new architecture. You usually start thinking about your new car in the first quarter of last year. This time we started two years earlier. ”
Formula 1 driver Nico Hülkenberg cheated this year. His win at Le Mans raised old questions again: who is faster, who is stronger, who is more efficient? The calendar makes it easy for us. The two so contrary cars sometimes drive on identical racetracks. Formula 1 and the WEC made guest appearances in Silverstone, Spa, Shanghai, Austin and Bahrain.
Each other vertex on the same route
Mercedes and Porsche have provided auto motor und sport exclusively with the GPS data for each of the fastest laps in Spa. 10,974 data sets for each lap on the 7.004 kilometer Ardennes route provide a breathtaking insight into what the two high-tech racers can really do. For example, when shifting up and down, the gears are sometimes only nine meters long. And that the motors are amazingly elastic. The Mercedes drives 640 meters in seventh gear in the Pouhon section of Spa. The fourth gear on the Porsche ranges from 154.5 to 200.4 km /h.
Basically, the Mercedes is faster on the straight despite its aerodynamic disadvantage. Because he's there in fullLength can fall back on electropower. Hülkenberg felt it in the Porsche: 'If the electric power is lost and you are still on the road with the small four-cylinder, then power is missing.'
You can tell from the top speeds on the two full throttle sections of 1,952 and 1,677 Meters in length. On the Kemmel straight, the Mercedes beats the Porsche with 337.3 to 321.1 km /h. The best value is achieved in different places. Formula 1 at 2,190 meters, the WEC at 1,539 meters. Then the electric motor gets out. Before the bus stop chicane, the Mercedes brakes in 156 meters from 324.1 to 75.5 km /h. The Porsche needs an extra 184 meters from 288.9 to 70.5 km /h because of 250 kilograms.
Formula 1 also has an advantage in fast corners, because the Porsche inhibits 250 kilograms of additional weight. Eau Rouge is clearly in favor of Formula 1 with 309.3 km /h to 280.0 km /h. 'You feel the weight especially when you change direction quickly. For example in the Pouhon curve. Compared to Formula 1, the Porsche is clumsy there,' explains Hülkenberg. Hamilton roared through on his qualifying lap at 279.1 km /h. The fastest Porsche driver managed 253.6 km /h in the sixth-gear left-hand curve.
In terms of acceleration, the Porsche is clearly superior despite its higher weight. More power, traction control and all-wheel drive pay off. As Hülkenberg vividly explains: 'I don't brake that much earlier. We get to the corners much more slowly than in Formula 1. The outcome is much easier with the Porsche because you have an all-wheel drive car. It just marches. Formula 1 circles you drive the car around La Source, you hit the gas and the rear is spongy. There is too much torque. You immediately have tires spinning and you have to modulate it very gently. '
The La Source hairpin shows the different driving lines. The WEC reaches its lowest speed of 64.9 km /h at 386 meters after the finish line. Formula 1 is still 83.3 km /h fast. The Mercedes comes to its slowest point at 405 meters with 71.2 km /h. Then the Porsche accelerates again and achieves 91.0 km /h. It takes another 145 yards to tie. Then the long-distance racer pushes the weight again.
Mercedes is 7.5 seconds faster than Porsche
With 19 corners and nine braking maneuvers, in which 101 kilowatt hours of energy are destroyed, goes the comparison of the lap times clearly to the Mercedes. The pole position with 1.47.197 minutes corresponds to an average of 235.215 km /h. On its fastest training lap, the Porsche is 7.570 seconds slower with 1.54.767 minutes. This corresponds to the weight factor, which in Spa amounts to 0.308 seconds per 10 kilograms, i.e. 7.7 seconds in total. Hamilton and Rosberg shift 51 times over the 7.004 kilometers. Nico Hülkenberg only had to use the rocker switch 42 times in the WEC-Porschepress.
And the efficiency? The sports car has the edge there. The Porsche is only allowed to use 1.98 kilograms of gasoline per lap at Spa. According to the regulations, the Mercedes may inhale more fuel: 2.19 kilograms per lap. In the endurance race car over a GP distance of 44 laps, it makes 87.12 kilograms. Formula 1 should use the 100 kilogram limit, but it doesn't because it is better to save weight than to take one liter too much on board. Nevertheless, today's hybrid racers are fuel-saving miracles. Two years ago they used a third more.
