Engine 3.7-litre, single-turbo V6 (diesel)
Hybrid system Single front-axle KERS, battery storage
7 André Lotterer, Benoît Tréluyer, Marcel Fässler
8 Loïc Duval, Lucas di Grassi, Oliver Jarvis
“We wanted to maintain downforce at the levels we had last year and reduce the aerodynamic drag.”
That target, says Audi Sport head of engineering Jörg Zander, drove the radical aero concept of the latest turbodiesel LMP1 contender to bear the R18 e-tron quattro name.
Audi Sport’s designers have picked up the nose of the new car and moved the driver cell backwards to create clean airflow under the chassis. The new concept is a reaction to rules that have cut the per-lap fuel allocation for the factory P1 hybrids by 7.5 per cent, placing an ever-greater emphasis on efficiency.
“We want to make sure we have a smooth flow to attack the underfloor and the rear diffuser,” adds former Sauber F1 technical director Zander. “We are trying to generate more downforce in the lower parts of the car.”
This aero thinking has coincided with the introduction of a new hybrid concept. Audi has replaced the flywheel energy-storage system of the new R18’s predecessors with a high-voltage lithium-ion battery, technology that Zander says is “similar but not the same” as Porsche’s.
That has allowed Audi to move to the 6MJ hybrid sub-class. That’s one step up from the 4MJ division in which it ran last year and one down from petrol-powered rivals Porsche and Toyota, but Zander explains that 6MJ is the optimum for a turbodiesel courtesy of the higher weight of the engine concept.
This explains why the move up in class has not been accompanied by the addition of a second means of energy retrieval. The new R18 – like its hybrid predecessors and unlike the rival contenders from Porsche and Audi – recovers solely via front-axle braking. An additional system could not be incorporated within the 878kg minimum weight limit and would also compromise the weight distribution.
The Audi drivers have to recuperate 6MJ at Le Mans – and a percentage of that at other tracks – with one system. That and the switch to a battery explains the massive step up in power of the motor generator unit. The mgu on last season’s R18 was rated at 200kW and this year’s at 350kW, or 268bhp compared with 496bhp. A 300kW limit will, however, be imposed (at Le Mans only) on safety grounds.
“With a single mgu you are closer to the limit of recuperating the energy that is required,” says Zander, “but considering the whole season, and in particular Le Mans, we think it is the most non-compromised solution.”
The conventional turbodiesel of the new R18 is a further refinement of the 120-degree, single-turbo V6 used in all previous cars to bear that type number. Audi, like its rivals, says it has been able to claw back a fair proportion of the power lost to the reduction in fuel flow.
Audi returns to Le Mans seeking a 14th victory with two cars driven by the same combinations as its regular WEC line-ups from last season. There is no additional or third entry (or a fourth as in 2012), courtesy of its agreement with Porsche.
Zander describes the new R18 – the sixth car to carry that type number and the third distinct design – as “complex”. That goes a long way to explaining a difficult programme of winter testing for Audi Sport. It was happy to admit that it was behind the game when it arrived at the official WEC test, known as the ‘prologue’, but stressed that it was catching up fast.
Its on-the-road victory at Silverstone suggests that process has been completed, at least in terms of performance. Question marks remain over the new car’s reliability, however.
“Here and Spa will be the most difficult for us, so we’re looking forward to Le Mans,” said André Lotterer, who ‘won’ at Silverstone with Benoît Tréluyer and Marcel Fässler until the car was disqualified for excessive wear to its front skid block. “Hopefully we can keep the reliability we had with our car today.”
Audi’s pace at Silverstone might just be very bad news for Porsche and Toyota ahead of the Le Mans 24 Hours. The latest R18’s hybrid system didn’t make it well suited to a circuit with relatively few heavy braking zones. Because the Audi has to do all its energy retrieval through one axle, the likelihood was that its drivers weren’t able to deploy the full amount of energy allowed under the regulations. That won’t be a problem around the Circuit de la Sarthe – think of the heavy braking involved for the four chicanes and the Mulsanne and Indianapolis corners. The 2016 R18 proved its speed on its debut, but not its reliability. The no7 car that won on the road didn’t have any problems, but its sister did. Audi didn’t have the kind of bulletproof car that we have come to expect right from the start of the season. The question is whether it can achieve that ‘unburstability’ when it goes up against Porsche’s proven contender around the Circuit de la Sarthe on June 18/19.
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