Mention the words “diesel” and “racing” in the same sentence and my mind first conjures up images of the beginning scenes from the movie “Smokey and the Bandit.” Remember that movie? You first heard a starter cranking over a big rig’s diesel powerplant, followed by huge blasts of black diesel exhaust emanating from the dual stacks, pointed proudly skyward just behind the cab. Fast forward to the scene at the truck rodeo, where truckers battle on a dirt circle track as the Bandit snoozes on a hammock in the pits.
Like this article? Sign up for our enews blasts here.
Navy CPO Scott Sigmon competes in pulling competitions for fun, a sport most of us would easily see a diesel dominate in.
But mention those same words to Audi engineers, and you’ll get an entirely different response.
Le Mans and Diesels
The 24 Hours of Le Mans is to endurance racing fans what the Daytona 500 is to NASCAR, but with a much older history. The first running of the race was back in 1923 on the roads surrounding the small town of Le Mans, France. The race has been held every year since, except for a French workmen’s strike in 1936 and a 10-year period between 1939 and 1949 due to World War II. Cars produced by Bentley, Alfa Romeo and Bugatti dominated the early races, and it didn’t take long before the competitors started developing innovations to their designs, looking for that competitive edge.
he goal of Le Mans is simple: See who can travel the farthest distance in a 24-hour period without breaking. Cars designed for this, and other endurance challenges, must balance speed with durability. Even with modifications to the course to limit speeds, though, cars running at Le Mans today routinely exceed 200 mph on certain sections.
No manufacturer has succeeded in meeting the challenge of Le Mans in recent years more than Audi. By the end of 2005, Audi had racked up five out of six wins at this historic venue with the R8. In 2006, Audi switched to diesel, fielding the R10 TDI. “Diesels provide excellent power and range, which is what is needed to be successful in endurance racing,” says Mark Dahncke, Product and Motorsports Communications Manager for Audi of America. “Fundamentally, a drop of diesel fuel contains more energy than a drop of gasoline.”
The front axle MGU and related systems is added to the R18 ultra, creating a four-wheel drive hybrid version dubbed the “e-tron Quattro.”
This was not the first diesel to ever compete in Le Mans, but it was the first to enter the winner’s circle. In 2007, Peugeot followed Audi’s lead and fielded a diesel car of its own. They came close to toppling the German automaker in 2007 and 2008, but it wouldn’t be until 2009 that they would score the win. Audi must have been a bit upset by the loss, though, returning in 2010 with the R15 TDI and claimed a 1-2-3 finish after engine and mechanical problems forced the four Peugeot entries back to the garage. In 2011, Peugeot came back strong to give the latest Audi, the R18 TDI, a hard run but the Audi held out and crossed the finish line just ahead of its closest rival.
During the last 13 years, Audi has racked up an impressive Le Mans scorecard. Its brand has won 11 out of 13 races, and over half of them were won with a diesel powerplant.
The R18 TDI hybrid was a dominating force in the 2012 season.
Enter The R18
2012 saw the entry of hybrids for the first time at Le Mans, with both Toyota and Audi fielding hybrid designs. The Audi R18 e-tron quattro is not only the first hybrid to win the race, but also the first Le Mans racecar that could be considered four-wheel drive.
“The R18 ultra forms the technological basis for the (2012) R18 e-tron,” says Dahncke. Other than the hybrid drive, the two cars are identical. The R18 ultra is the lightest Le Mans Prototype ever built by Audi Sport, using ballast weight that can be positioned as required to bring the car to it’s minimum required weight of roughly 1980 pounds. It uses a 6-speed gearbox housed in a composite case and an electro-mechanical steering system, which provides the drivers with better feedback. The V6 TDI engine was completely reworked in order to achieve the required reduction in horsepower. The intake air restrictors were reduced to 45.8 millimeters (from 47.4 millimeters) and maximum turbo boost pressure was reduced as well.
Racing innovations translates to innovation on production cars, according to Dahncke, and the opposite is also true.
Audi drivers celebrate winning the WEC championship with the R18 diesel hybrid.
“You learn how to optimize engineering and the calibration of the engines to achieve excellent performance and fuel efficiency,” Dahncke says. “The Audi Sport Team engineers and the powertrain engineers meet regularly and provide each other with the latest in learning. Of course, the racing side of the equation delivers more extreme testing knowledge that is then applied to our production diesel engines.”
And what better form of racing to test a design that might end up in your driveway than one that punishes the powertrain for 24 hours straight?
Audi adopted a flywheel accumulator hybrid drive system for the R18 e-tron quattro since the requirements at Le Mans differ slightly to those found while operating a hybrid in normal highway driving.
“A high power density is crucial during energy recuperation,” says Christopher Reinke, Technical Project Leader LMP (Le Mans Prototype). “The accumulator must be capable of absorbing a lot of energy within a few seconds during the braking stage.”
The R18 ultra made impressive showings, continuing the Audi diesel racing saga.
The system integrated into the front axle is comprised of two drive shafts, the Motor Generator Unit (MGU) including planetary gears, an electronic flywheel accumulator alongside the driver, an insulation-monitoring unit for high voltage safety and the control system.
The recuperation of energy occurs during braking. In the process, the wheels drive the MGU. The race organizer defines the braking zones permitted. The MGU accelerates electrically a carbon-fiber flywheel, which runs in a high vacuum. After the corner is taken and the driver accelerates again the system delivers the energy to the front axle, making the car four-wheel drive (quattro). The regulations allow 500 kJ (kilojoule) of energy to be transferred to the front wheels between two braking phases. The planetary gears adapt the transmission ratio during acceleration and braking. The two independently powered axles on the R18 hybrid are synchronized exclusively via electronic control strategies. This control occurs automatically without driver intervention.
The R18 ultra made impressive showings, continuing the Audi diesel racing saga.
The entire charging process (recuperation) is controlled by two parameters: the deceleration of the car (the braking process) and the accumulator’s state of charge. The energy emission process (boost) is defined by the minimum speed of 120 km/h as stipulated by the regulations, the race strategy selected, the throttle pedal movement and acceleration of the vehicle.
“The greatest challenge was to find the ideal compromise,” Wolfgang Appel, head of vehicle development at Audi Sport, says in a factory press release. “It was a question of weight, performance, hybrid concept, regulation constraints and the packaging, which means perfectly balancing the distribution of all the components in such a way that no appreciable disadvantages arise in the conventional vehicle since both cars are absolutely identical, with the exception of the hybrid system, in design and construction.”
A warning lamp and sticker stipulated by the regulations are the only external differences between the R18 e-tron quattro and the R18 ultra. The bodywork covers the driven front axle and the coolers. Only an operating panel below the normal dashboard in the cockpit identifies the R18 as an e-tron quattro to the driver.
But according to the drivers that piloted the R18 e-tron quarto hybrid diesel to not only a win at Le Mans, but also to the WEC championship in 2012, the differences are far more noticeable.
The unique DeltaWing was named one of Popular Science’s “2012 Best of What’s New” products and innovations.
The Shape Of The Future
The Nissan DeltaWing was designed to compete in endurance racing events. That, in and of itself, is not an unusual challenge for a designer to take on. What does make the DeltaWing unique is the design goals set for it.
“The Nissan DeltaWing was designed and built with the initial aim of completing the famous 24 Hours of Le Mans using just half the fuel and half of the tires of contemporary sports prototypes,” says Darren Cox, Nissan’s Global Motorsports director. Its unique design features half the weight, half the horsepower and half the aerodynamic drag of a typical Le Mans car. The DeltaWing tips the scales at 1,250 pounds and rides on tires that are only four inches wide. Using about the same horsepower as a high-end family sedan (300 bhp versus the 600-plus typical to other Le Mans cars), the car is able to reach speeds of 200 mph.
Designed by Ben Bowlby and using a Nissan 1.6 liter in-line four built by Ray Mallock Engineering, the DeltaWing qualified 29th with a best time of 3:42.612. An unfortunate accident at lap 75 resulted in a “DNF” for its inaugural race. Later in the year, the car scored its first race finish at the Petit Le Mans race held at Road Atlanta in October 2012, taking fifth place overall despite starting from the back of the pack of 42 entries. Look for even more successes in the upcoming 2013 season.
Germans Launch “Clean Diesel” Campaign
The mental image of a clanking, clanging diesel car belching black smoke out of the tailpipe is an image many American drivers still retain. But five German automakers (Audi, BMW, Daimler, Porsche and Volkswagen) are starting their first joint information campaign for "clean diesels" in the U.S. in an effort to reeducate car buyers.
Joined by Bosch, they will publicize the advantages of modern diesel passenger car technology over gasoline engines in terms of cleanliness, consumption and performance under the slogan "Clean Diesel. Clearly Better." slogan. Their common goal is to create a multi-brand information platform for clean diesels in the U.S. market and to make the clear advantages of this technology better known using first-hand sources.
The market share of diesels among all newly registered light vehicles in the U.S. is low (2.6 percent) when compared with a diesel share of 55 percent in Western Europe. But sales of diesel passenger cars by German manufacturers (who control the lion’s share of the market) have more than doubled over the last three years. In the first nine months of the 2012, approximately 69,600 diesel cars were sold in the here, as compared to only 30,600 back in 2009. This is an increase of 127 percent.
The Audi 3.0 is one of the powerplants soon to become more available.
Using brief examples from everyday driving, the website (www.clearlybetterdiesel.org) explains the facts about the dynamics of the diesel drive train and its advantages in fuel consumption, CO2 emissions, low noise emissions and refueling costs and also clears up outdated concerns regarding diesel cars. For example, website users can not only calculate the consumption advantage of a diesel vehicle, but can also hear how quiet a modern clean diesel drive train is these days compared with a passenger car from the 1990s.
Audi (and its sibling company VW) have made a major commitment to clean diesel technology by offering TDI as an option in its most popular model lines. The new TDI-powered A8, A7, A6 and Q5 made their debut at the Los Angeles Auto Show and a new redesigned A3 with TDI is set to join the lineup in early 2014.
According to Scott Keough, president of Audi of America, “Owners of Audi TDI engines have helped save over 4 million gallons of gasoline, or the equivalent of 240,000 barrels of foreign oil, since the introduction of the Audi TDI in 2009.” In addition to the “Clean Diesel. Clearly Better.” campaign, Audi will expand the conversation surrounding modern diesel technology via social media, using the hashtag #FuelForThought.
Subscribe to Motor Age and receive articles like this every month…absolutely free. Click here
