Report: GS Yuasa To Produce Batteries For Hybrid Cars
ConocoPhillips CEO Calls for Improved Fuel Efficiency

Audi R10 TDI Diesel Wins Le Mans

The winner: No.8 Audi Sport Team Joest R10. Photo: Bertrand COUSSEAU

An Audi R10 diesel (No. 8) won the Le Mans 24 Hours race this weekend—the first diesel-powered car ever to do so—with a four-lap lead over the second-place car. A second Audi R10 (No. 7) took third after having to replace a turbocharger earlier in the race, a delay that cost it 10 laps.

The Le Mans 24 is an endurance race—the winner is the car that covers the most distance in 24 hours; cars are driven by teams. The No. 8 covered 380 laps on a 13.65-km (8.48-mi) circuit in this year’s race.

The Audi R10 TDI is powered by a completely new all-aluminum, 5.5-liter, twelve-cylinder bi-turbo TDI engine that delivers more than 485 kW (650 hp) and more than 1,100 Nm of torque. (Earlier post.)

The V12 TDI used in the R10 is the first Audi diesel engine with an aluminium crankcase. The cylinder-bank angle is 90 degrees. The V12 TDI has, like Audi production car engines, four valves per cylinder and twin overhead camshafts. The common rail fuel injection system exceeds 1,600 bar. The V12 TDI is equipped with a pair of diesel particle filters.

Peugeot has announced that it will enter the 2007 Le Mans 24 Hours race with a new diesel car—the Peugeot 908—powered by a 5.5-liter V-12 HDi diesel engine equipped with a diesel particulate filter system. (Earlier post.)

The Le Mans 24 Hour race set an attendance record this year, with a total of 235,000 spectators.


Rafael Seidl

Le Mans limits only the volume of the fuel tank. Diesel has ~13% more energy by volume so that means you can do ~16 laps on one tank vs. ~14 on gasoline. Fewer pit stops gives you a huge advantage in endurance racing. Note that the greater efficiency of the diesel engine in part load matters little when you spend 70% of the time at full throttle.

That said, hats off once again to Audi. Their four-lap winning margin was more than due to the fuel advantage alone. They have a world-class engineering and race team that has now earned its stripes in Le Mans seven years running. Perhaps the hardest part was delivering a lightweight diesel engine that could take advantage of the higher fuel density, and a gearbox that could cope with the stupendous 1100 Nm of torque. The R10 has a 650hp V12 with an aluminium crankcase - production diesels all feature cast iron blocks. Peak rated RPM is ~5,500 vs. ~4,500 in a production diesel. It helps if you have an oil major custom-tailoring your fuel for you (GTL has a high cetane number).

Sports cars are the only vehicle segment that had hitherto not featured diesel engines, because customers perceived the combination as an oxymoron. With this win under their belt, it's probably safe to say that Audi will want to offer a diesel in a future sports car. Here's what it might look like:


"Fewer pit stops gives you a huge advantage in endurance racing." Hm, following that (drive) train of logic, could there be an advantage to Le Mans race cars using regenerative braking?

Eric H

Regenerative braking requires someplace to store the energy to, and then another system to get it back. Batteries store less energy per pound than diesel contains, and the electric motor and support system (including gear box) is more added weight. There's a reason they went with an aluminum block.


"Le Mans limits only the volume of the fuel tank. Diesel has ~13% more energy by volume so that means you can do ~16 laps on one tank vs. ~14 on gasoline."

So, the race regulation should be revised.
The tank capacity should be mega joul energy based instead of litters.


but not to forget that diesel is ~15% heavier then gasoline.


A diesel engine's greater fuel efficiency makes for fewer pit stops. The winning Audi made 27, while the Pescarolo in second made 32.


A properly designed and built, Diesel-Hybrid could easily win next years Le Mans.

hampden wireless

Yes batteries have less power per lb then fuel but they are getting recharged and used over and over in a single lap. The challenge would be to size the system right so it was filled and used to the max often. You would not care about long term battery life but you would care about recharge and discharge rates. Maybe supercaps?


You would be able to change the batteries after every race so you could really go for the most advanced chemistries for fast recharging and lightweight. All this would be worthless for street use (the battery portion...though efficient controllers and motors could carry over).


“Production diesels all feature cast iron blocks..”

You gotta be kidding. At least dozen diesel engines now feature aluminium block. Among companies producing aluminium diesel engines are Volvo, WV, Isuzu, Toyota, Mercedes (notably performance 3 liter), to name a few. Switch to aluminium block is a major recent achievement in diesel technology.

Thomas Pedersen

While such batteries might be worthless for street use, some important chemistry and stress test could be covered by motor sport's aggressive R&D.

They could start off light - maybe a 50 hp motor/generator with a small supercap. That shouldn't weigh much..?


Yup dead right Andrey, you beat me to it!

They have aluminium blocks but with cast in iron bearing caps and liners and so forth.


Why batteries? Why not ultra caps?


Whoops, hampden wireless said that already, i.e., super capacitors == ultra caps. Very high energy density.

The challenge would be how to install a light strong PM servo in a very durable, dual-clutch tranny.

An Engineer

Le Mans limits only the volume of the fuel tank. Diesel has ~13% more energy by volume so that means you can do ~16 laps on one tank vs. ~14 on gasoline. Fewer pit stops gives you a huge advantage in endurance racing.
So why is this the first diesel to win Le Mans? It is still an achievement, no matter how you look at it.

Rafael Seidl

An Engineer -

the winning engine achieves 86 kW/L vs. ~60 in modern production diesels. Power per unit of weight no doubt exceeds production engines by an even greater margin. It must withstand peak firing pressures of ~200 bar (perhaps more) at 5000+ RPM for 70% of the 24 hour race.

It's simply extremely hard to prevent engine failure given these demands, so up to now virtually everyone focussed on high-revving gasolien engines instead. There have been some diesel rallye cars, though.


If my memory is not all that bad, there was a a biodiesel car racing at Le Mans a few years back (Team Nasamax). It would be interesting to see if this achievement (the R10 winning Le Mans) would spur a bit more interest in that technology again.

Chris Ellis

Check the ACO regs. Gasoline turbo engines are limited to 4.0 liters. Diesels can be up to 5.5 liters. That's a 37.5% bigger engine, so fuel energy density isn't the only advantage Audi enjoyed. Hybrids and ethanol are currently off limits.

Now let me speculate why the ACO has set the rules up this way. The recent announcement by Peugeot that they will return to Le Mans with a diesel gives us a clue. If Renault also returns, Le Mans will attract extra hordes of French Peugeot and Renault supporters. It's bums on seats, folks! Plus more sponsors, of course.


I'm taking a stab here but given the forum I'm sure someone will correct me if I'm wrong. Isn't this the first race car at anywhere near this level of competition to incorporate emission controls? I can't imagine that they have been a high priority on other projects. Also does anyone know how much of a power hit the particulate filters might have on the final HP and Torque numbers?

David S Billington

It looks as though the Isle of Wight has another first in its Biodiesel plant. From the comments above it would seem that Biodiesel is the perfect fuel as it gives such low emisions or as on my 1985 Shogun practically none at all. If my poor old 150,000 mile car can do it I do not see why it cannot be used as a 100% fuel in these high performance engines, mine makes less noise and runs much more smoothly with no smoke being produced. It would be interesting to hear comments from the technical boys who work on these projects and see if they want to use Isle of Wight Biodiesel

The comments to this entry are closed.