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Audi R8 TDI Le Mans Prototype: Visionary Thinking
Audi continues to impress and set new standards for already high German engineering and technology. Consider Automotive Rhythm’s long-term luxury Audi A8 L, a vehicle which turned many non-believers into fans of the storied marque.
“It’s better than a Benz,” is a comment we’ve been receiving from readers who are into German luxury cars. I’ve always said the four rings can more than hold their own.
Automotive Rhythms recently accepted an invitation to attend the 12 Hours of Sebring Endurance Race held at Sebring International Raceway in Sebring, Florida. Audi has owned this race since 2000, winning eight consecutive races with both gas and diesel powered racecars. Yes, I said diesel. We’re not talking about the old, slow, stinkin’ diesels of the past. Audi’s on the track with a 650 horsepower, twin-turbo V12 diesel car that rocks. It’s called the R10 TDI.
Audi is using the R10 TDI to promote “green” racing. Don’t laugh, as they are on to something. You can tell immediately when you watch the R10s blow by the competition on Sebring’s Ulmann straight. The R10s are quiet, so quiet in fact you wonder how they open the huge can of whup ass they bring to every race. They emit a mellifluous rumble, while the rest of the field yields an aural assault - you’d better be armed with earplugs or your ears will ring for days.
To better understand the R10’s “stealth” diesel technology, I spoke with Johan De Nysschen, executive vice-president, Audi of America. “The issue with diesels is that we’ve built a more powerful car that develops torque and horsepower at far lower engine speeds than our competitors. For example, while the gasoline engines may run at 9-10,000 rpm to get max power, our diesels run at 5,000 rpm, greatly reducing noise, fuel consumption and engine wear. Turbochargers further quiet noise, and we also use particulate filters to show Audi’s commitment to a cleaner environment, and these filters also reduce noise.”
So if Audi is having so much success with potent diesels on the track, why not build a diesel supercar for the street? They have, and it’s called the R8 TDI Le Mans, after the famed French racecourse of the same name (where Audi also dominates, by the way). As part of our Sebring race weekend, a handful of journalists were invited to drive the only R8 TDI prototype in the U.S.
Physically, it’s the fraternal twin of the world class R8 sportscar. All of the similar lines are there, until you get up close to the TDI. The first major difference you’ll notice is a carbon fiber NACA duct flush mounted into the roof, feeding two carbon fiber air intakes for the R8’s 6.0-liter V12 TDI powerplant. And I called it a “powerplant” for a reason, as the R8 TDI pumps out 500 horsepower and an incredible 738 pound-feet of torque!
Under the R8 TDI’s hood, two turbochargers are located on the outside of the engine's V, each of them supplying one bank of cylinders. Thanks to their variable turbine geometry, the turbos respond quickly – even at low engine speeds - and operate very efficiently. The twin turbos generate up to 2.6 bar of boost pressure, playing a crucial role in producing the huge torque that the R8 TDI maintains from 1,750 to 3,000 rpm
The R8 TDI Le Mans also employs similar “green” technology of its racing brethren. At the heart of the emissions system is a special catalytic converter, oxidizing catalyst and particulate filter. Another major component of the system is an additional tank containing an aqueous urea solution called “AdBlue.” Small quantities of AdBlue are injected into the exhaust system. Then, hot exhaust gases break the solution down to form ammonia that splits the nitric oxides into clean nitrogen and water. The system remains effective for the life of the vehicle.
The Audi R8 TDI Le Mans already fulfills “Euro 6” emissions standards that are scheduled to take effect in 2014 and call for sharply reduced nitrogen oxide emissions. By also designing in ultra-precise fuel metering via the R8 TDI’s “common rail” system, Audi has made full use of current clean diesel technology. We expect that Audi’s engineers will also shoot for full emissions certification when it’s released here, including California’s ultra-clean emissions standards.
The R8 TDI’s interior features a three-spoke sport steering wheel with a polished aluminum flat lower edge. This gives the car a racing feel and look, and also facilitates entry and exit for the driver.
The start/stop button for the engine and the “Drive Select” switch with the Dynamic/ Sport/Race settings are located on the steering wheel. The Drive Select switch controls engine and transmission electronics as well as the magnetic ride dampers in each of three different modes.
In “Race” mode, instrument lighting changes from white to red. The navigation system shows a combined display with lap timer and navigation information for the racetrack being driven. Or supplementary information such as centrifugal force and turbo boost pressure can be displayed.
The view to the rear is severely compromised by the aforementioned NACA duct and carbon fiber air intakes. To help offset this, the R8 incorporates a rear view camera that can be used in reverse and forward modes, giving you an electronic view of your blindspot.
Outside, in addition to the NACA duct, the R8 TDI gets more carbon fiber and polished aluminum and chrome trim than its gas-powered brother. For example, an aluminum lip extends the circumference of the R8 TDI, further enhancing its ground effects look.
We drove the prototype on the remaning airfield section of Sebring Raceway, which in its entirety used to be a WWII airfield for B17 Bombers. Full spec R8 TDI’s sprint from zero to 62 mph in just 4.2 seconds and reach a top speed of 186 mph. Peak torque is achieved at only 1,750 rpm, with effortless acceleration in every one of the six forward gears. To slow the diesel’s locomotion, Audi uses massive carbon ceramic brakes front and rear.
Driving the R8 TDI, we were not allowed to exploit the prototype’s full power, which had been purposely dialed back as Audi works to improve the strength of driveline components to handle the R8 TDI’s prodigious torque.
But the point of the exercise was clear, when this concept goes into production (no word yet on an official release date) this car will rewrite the supercar class and will certainly steal the spotlight from Ferrari, BMW, Lamborghini, Mercedes-Benz, Porsche and Maserati by proving that Audi’s visionary diesel technology is a viable pathway to green performance.
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