Audi R10 – The Detail
Are we looking at the winner of the 2006 Le Mans 24 Hours?

After thinking long and hard about the details that became apparent during a very busy three hours in Paris on Tuesday (December 13), it would be hard to argue against the R10 winning on its Le Mans debut. But that’s getting ahead of ourselves.

The launch was all about the car more than the programme.

The scene of the launch was the Trocadero in the centre of Paris, overlooking the River Seine and the Eiffel Tower. The first confrontation between Audi and Peugeot diesels, below?

“The catering manager of the Trocadero is the grand-daughter (or great grand-daughter) of Gustav Eiffel,” explained Audi UK’s David Ingram, explaining how it came to be that Tom Kristensen drove the R10 across the bridge over the Seine, gave it a quick rev or two – very quietly – and then parked the brand new car beneath the terrace.

Incidentally, David Ingram suggested that Audi Sport UK wouldn’t be getting hold of an R10 “before 2007”, which hinted at the (perhaps) lack of availability (to others) of R10s in 2006. We’ll have to wait and see on that subject (see below).

The formal press conference was a very smoothly conducted affair, led off by Professor Dr. Martin Winterkorn, Chairman of the Board of Management of Audi AG, followed by Dr. Wolfgang Ullrich, Head of Audi Motorsport, with interesting contributions by seven-times Le Mans winner Tom Kristensen (the latter two both have a remarkable command of European languages).

After the press conference it was a chance to grab the full attention of the other Ulrich – Ulrich Baretzky, Head of Engine Technology at Audi Sport.

He’s the man who was responsible for the R8 engine – and the R10, 5.5 litre, V12 diesel is his ‘baby’ too. The diesel engine is the heart of the R10, so here was the man to quiz about the reaaly new feature of the new car. Baretzky did clarify that oft-used statement about R8 engines never failing: “We never had one fail in a race. It is different in testing, when you have to take the engine to the limit…”

So it’s a 12 cylinder diesel – and a very special racing engine in one important respect.

“It’s the first purpose-built, diesel racing engine. Every other racing diesel has been developed from a production engine.”

So why did you choose 12 cylinders? (perhaps the first question should have been – Why did you choose to build a diesel? – but we’ll get to that answer in due course)

“We carried out a feasibility study with 10 and 12 cylinder engines. Because the combustion pressures are so high, it is better to distribute those pressures across 12 cylinders rather than eight or ten.”

Ulrich Baretzky (right) mentioned a figure for the pressures within a production diesel of 160 bar, “but we are far beyond that with the R10.”

Similarly the injection pressures of over 2000 bar are well beyond the 1600 bar of production engines.

So huge internal pressures within the combustion chambers (and in the common rail injection system), but isn’t the V12 a massive engine as a result of having to cope with those pressures?

“If you took a fuel injection (petrol) engine of the same size, the weight of the two would be similar. (Or put another way) if you took the 3.6 litre engine from the R8 and added four more cylinders, then you would have the same weight.”

Thinking about that remark, he’s suggesting that cylinder for cylinder, the two engines are the same weight, it’s just that one is a 5.5 V12 (5.5 is the maximum allowed for a diesel), the other a 3.6 V8.

The diesel engine is all-aluminium, rather than, say, an iron block, so the Audi engine wizards have managed to keep the weight down as a result. “We have designed it in a very clever way” (no elaboration on that point, obviously), yet are still very confident that the V12 will be as reliable as the (petrol) V8.

“That has to be the target – to make this engine as reliable as our other engines.”

Ulrich Baretzky then emphasised a point made by Prof. Dr. Winterkorn and Dr. Ullrich – that Audi is heading down the diesel road because that will allow the company to improve its road-going diesel engines, which will benefit the customer.

“Nowadays, every second Audi is delivered with a TDI engine,” said Prof. Dr. Winterkorn, earlier. “We expect that he percentage of diesel engines will be even larger in the future.”

Doubtless a Le Mans win or two wouldn’t exactly harm sales of diesel-powered Audi road cars.

The power and torque figures of the V12 (650 bhp and 1100 Nm, with a power band between 3000 and 5000 revs) are staggeringly impressive – but just like the R8, but more so, the diesel isn’t going to be very stimulating aurally.

“From the figures and from the physics, a diesel engine for racing has to be low-revving,” says Urich Baretzky. “I’ll be very interested to see how anyone else gets on with a high revving diesel engine…”

A low revver has advantages in fuel economy and fewer gearchanges, he believes, and he predicted that “we are calculating two more laps than with our R8 engine.” Baretzky left that statement deliberately vague.. two more laps than the original R8, or the FSI R8 with a 90 litre tank, or the more recent car with 80 litres?

He also commented that “we know from the R8 that the driver has a big influence on the economy, and we will face a similar situation with the diesel.”

When Tom Kristensen revved the V12 out on the public road earlier, there was no sign of any smoke from the engine.

“No smoke at all. That is a combination of the very efficient combustion and the particle filters (two). We won’t need to change the filters during a 24 hour race – in fact, they clean themselves. I’m really interested to see how long they will last (in an extended test).”

Bartezky summed up his design philosophy for this engine as “no flames, no smoke, no noise. No one wants a screaming engine in a road car, and the race engine will be no different. I don’t like screaming engines.”

F1 seems to have no appeal to these people.

Frank Biela is the only man to have driven the R10 in anger (in a shakedown test on November 29), and that test was to “gather a lot of data about the car. That was the first time the engine had run in the car, on a track.”

Baretzky admitted that after that first test that he and his engineers do not yet have any sense of the outright speed of the car – and as usual, they won’t know what that speed is at Le Mans (except on the computer), until the Le Mans test day on the first weekend in June.

Last two points from Herr Baretzky.

Could Audi have used a production diesel engine as the basis for the Le Mans car?

“We tested the 4.2 litre V8 production engine, and it was tremendously reliable – but it’s a cast iron engine. We wanted to make a big step forward with the race engine – that’s how we do things.” So perhaps Audi production engines will be much lighter in future.

“Have you seen my model,” he asked?

From within a cardboard box, he proudly revealed his model 3.6 twin turbo V8.

“It’s not as tough as the real one – I’ve damaged it already.”

Allegedly, someone was taking photographs of the petrol engine at Le Mans, and Herr Baretzky agreed to forward the CAD drawings of the V8, so the modeller had every detail needed to make the model engine that the Head of Engine Technology is shown holding.

So what about the rest of the car?

It has the standard LMP1 design cues (with some unique features), it has a longer wheelbase than the R8 (thanks to the longer engine), it was built by Dallara again, it has “overly wide” front tyres, to reduce understeer, the chassis is (largely) the bodywork (“the majority of the carbon-fibre parts belonging to the R10 monocoque are now suspended directly in the airflow and therefore require no additional fairings”), the power steering is now electric rather than hydraulic, the gearbox’s internals “can be changed within a short period of time”, data logging information is displayed on the car’s steering wheel, and an electro-pneumatic shift system changes the gears (of the Xtrac derived gearbox, which is lighter than in the R8, despite having to handle all that torque).

Basically, the R10 chassis seems to have all the strengths of the R8 – but better.

“It’s impressive just how the engine keeps on pushing even in the high gears,” said Frank Biela, after that shakedown test at the end of last month.

We’ve been sure for months that it was going to be a diesel – but Audi Sport has been able to keep the details a secret, since settling on a 5.5 litre V12 in September 2003.

This project is a huge step forward, and although it is over two years old already, everyone at Audi Sport is very conscious of the fact that the 2006 Le Mans event is only seven months away – and the R10 has had only a shakedown.

But every day between now and Le Mans “is planned”, and the engine has already covered over 1000 hours out of the car. That time on the dyno. will be tripled before Le Mans: you really can’t imagine the engines being any kind of a weak area next June.

Neither will the team behind the R10: Reinhold Joest will be responsible for running the pair of cars at Sebring and Le Mans.

But as regards R10s running elsewhere in 2006, “nothing has been confirmed as yet,” said Herr Ullrich. He wouldn’t confirm Audi’s DTM plans (or not) either.

So there’s more news to come on this project, specifically any other 2006 programmes (ALMS, Le Mans Series and Japan are being considered), but that’s just about all the news for now. It was quite an eventful day.

So does it scare the pants off everyone else? Is this why Henri Pescarolo was so bitterly disappointed not to have grabbed his Le Mans chance in 2005? Has the R10 made France its second home already?
MC