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24 Hours Of Diesel Power at Le Mans

Imagine Driving From Los Angeles to New York at 120 mph—In One of These…

Text By: Joe Rae, , Photography by Courtesy Of Audi,

Suppose you and your buddies decide to drive from Los Angles to New York City one afternoon. You plan to leave L.A. at 3 p.m. on Saturday and arrive in the Big Apple at 3 p.m. Sunday. Of course, you’d have to have a couple of good drivers to take turns at the wheel, and probably someone who could do a little wrenching for you on the way. Oh, and there would be one other thing: The diesel vehicle you drove better be able to average 120 mph for the entire trip.

Sound like mission impossible? Well, this is the exact scenario the winning Audi Le Mans Prototype One (LMP1) team went through in early June at Circuit de la Sarthe in France. Audi conquered four other diesel- powered Peugeots and a host of gasoline-powered race cars in what many consider to be the most challenging motorsport event in the world—the 24 Hours of Le Mans. And it did it with a 3.7L V-6 diesel engine that was not only able to average more than 120 mph for the race but regularly topped 200 mph on the famous Mulsanne straight.

TDI Win On Sunday, TDI Sale On Monday
Audi believes in the old adage “What wins on Sunday, sells on Monday” and has carved out a niche market as a result of its wins in major races. Audi uses what it’s learned on the racecourse to improve the daily drivers of its fleet. But it has also borrowed from the production fleet to improve its race car, as is evident in the LED lights that illuminate the way for the vehicle.

We must remind you that in Europe, the price of fuel is around $7.00 a gallon, and TDI gives consumers the best value for transportation. Audi and Peugeot see diesel motorsports as a direct channel to market, and both have used racing to market their brands and improve their cars.

Diesel Is Changing the Rules
During the last five years, teams that have chosen to go with the diesel engines have experienced more and more restrictions from the Automobile Club de l’Ouest (ACO) sanctioning body. When Audi first came to Le Mans with a diesel in 2006, it was a 5.5L V-12. This year, the powers that be restricted engine displacement to 3.7L.

The Peugeot team, which has challenged the dominance of Audi in endurance racing, won the Le Mans race in 2009. But the Teutonic Knights of Ingolstadt, Germany (Audi’s home base) are dominant in the crown jewel of endurance racing, winning the 24 Hours of Le Mans four of the last five years.

Tale of Two Engines
With just 3.7Ls to work with this year, each team had to come up with a new engine. Peugeot chose to build a 90-degree V-8, while the Audi team introduced a 120-degree V-6.

Bruno Famin, Peugeot Sport’s Technical Director, noted Peugeot wanted to stay with technology it knew, and therefore simply reconstituted its 5.5L V-12 into a 3.7L V-8. “We tried to use our know-how in engine development. Basically, the engine’s block, pistons, and combustion chambers are an improved version of what was used in the V-12. We just reduced their size to comply with the 2011 rules. By keeping the engine architecture the same, it makes the new V-8 easier to work on,” he said. The Peugeot V-8 uses twin turbos as it did on the V-12, but the engine uses an updated Bosch injection system.

Audi’s 540hp V-6
Initially, Audi came to Le Mans with a 5.5L V-12 and twin turbochargers. Then, in 2009, it shrunk the outside of its engine by building a 5.5L V-10. But gasoline-burning teams whined about the advantages of the diesel, and the ACO, looking to ensure some semblance of competition, listened.

At the end of the 2009 season, Audi began designing its close- cockpit R18 TDI. No idea was left on the table as the team put the corporate motto, “Vorsprung durch Technik” (forward advancement through technology), to work.

When it came to the engine, Audi made a bold choice to go with a V-6, but not just any V-6 design. The engineers came up with a compact 120- degree cylinder-block-angle V-6, which allowed for a lower center of gravity as well as the opportunity for what it called “electrification” in the future.

First, rather than the twin turbochargers of past, the V-6 utilizes a single turbocharger that sits above the engine and draws its air directly through the air scoop mounted in the roof of the chassis. Developed with Garrett, the turbo utilizes variable-turbine geometry, just like the Le Mans-winning R15 V-10 TDI.

Ulrich Baretzky, Head of Engine Development for Audi, noted, “Without VTG, the response characteristics of one large turbocharger would just be too slow.” In the end, Audi was able to produce a 540hp V-6, and with the improvement in aerodynamics of the car, it kept the performance in the same realm of the 5.5L V-10 R15 TDI .

A couple of other differences between the V-6 Audi and your normal diesel include the fact that this diesel is whisper quiet. As Dr. Ullrich notes, “Noise is unused energy. A quiet engine is more efficient than a loud one. At the moment, being quiet sets us apart. Just as long as there are others that are loud, we make a lasting impression.”

This Audi is more efficient from a fuel economy perspective as well, getting 20 percent better fuel economy than the 3.6L direct-injection gasoline engine Audi raced with in 2000. Additionally, injection pressures have increased from 23,000 psi with the R10 to something approaching 36,000 psi in the R18.

Finally, Audi logs 1,005 channels of data from each vehicle. That information is recorded, monitored, and transmitted to the data center in the pits. At Le Mans, that amounts to 16 MB of data each lap for engineers to study.

By Joe Rae,
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