Say goodbye to the screaming V8s. For 2019, the Deutsche Tourenwagen Masters (DTM) will be doing away with their longstanding V8 formula, and—shock and horror—will instead employ turbocharged inline-fours. Audi has already announced its entry into the new engine formula with its own four-cylinder capable of 640 horsepower. Better yet—the new powerplant offers more than just a big bump in horsepower.
The change is engine regulations has not been done solely for reasons of efficiency, and the series isn’t getting soft. With more power, much more torque, half the weight, a more compact package, and a handful of other benefits, the new motor ought to revitalize DTM—not that it was in need of much help.
Background on the Change
Ten years back, rumors of a robust and fuel-efficient four-cylinder engine for worldwide competition started to circulate. Better known as the Global Race Engine, the project moved on in semi-secrecy as a joint effort between DTM and Super GT. In the last few years, Audi got invested and started putting together their own version.
The new RC8 motor is a turbocharged, twin-cam, 2.0-liter TSFI engine designed and manufactured from scratch. As Audi’s racing history is already rich with forced-induction gems, they had the background to go to extreme lengths with the RC8, which produces an astonishing 610 horsepower in normal conditions. However, that’s not the peak output level—it also features a “push-to-pass” function which allows drivers to bypass the fuel flow restrictor (FFR) and increase the rev limit for five seconds, 12 times per session. During these brief squirts, the drivers will enjoy another 30 horsepower and the ability to sprint past their opponents in old-school fashion.
A Tie to Road Cars
Not only does new motor provide the drivers another 100 ponies to play with, it’s established a clearer link between Audi’s production cars and their racing cars, since many of the road-going brethren sport a fundamentally similar engine which can benefit from motorsports development. Ulrich Baretzky, Head of Engine Development at Audi Motorsport, elaborated, “In terms of weight and lightweight design—especially in the context of avoiding CO2 emissions—we’re pointing out a few approaches that will hopefully find their way into future road-going vehicles – like in the case of the first TFSI for Le Mans and the TDI.” The motor also has to run on pump RON102 fuel.
Additionally, this switch has helped in finding the ideal balance between power and efficiency. Under the new Class 1 regulations, DTM cars have their fuel flow rates limited to 24.7 gallons per hour, “The specific consumption of the DTM engine is extremely low and now within ranges that used to be typical for diesel engines,” added Baretzky.
The reduced size and weight of the new motor brings plenty of astounding performance advantages, too. For one—the featherweight internals allow the engine to spin to a stratospheric 9,500 rpm. Even more importantly, at just 187 pounds, the minuscule motor is roughly half the weight of the 328-pound V8. This reduction in engine mass brings the dry weight of the Audi RS5 DTM to just a tick under 2,200 pounds. Drivers have already remarked on the improved agility this new powerplant offers. “The new car feels like a go-kart and is huge fun,” said Rene Rast.
“The improvement of the power to weight ratio can be seen with the naked eye. With that, we’re taking a clear step toward the ‘ride on a cannon ball’ that Gerhard Berger would like to see,” remarked Dieter Gass, Head of Audi Motorsport.
Just think about that. With rapid shifts, the strong traction from the 320-section rear slicks, a 0-60 time of 2.8 seconds, and the power-to-weight ratio of 3.5 pounds per horsepower, it’s hard not to get a little giddy. If a reference point for straight-line acceleration is needed, a Bugatti Veyron SS boasts a similar ratio. It’s a far cry from the ~300 horsepower of the old DTM machines.
An Arduous Two Years of Development
Predictably, making something this small both robust and reliable was no mean feat. The development process—2.5 years full of endless cups of coffee and consoling calls home to neglected wives—was still relatively short for the demands the new motor imposed on the team. In addition to better efficiency, the new regulations mandate the engine lasting the length of a season—roughly 3,700 miles—before a rebuild.
To ensure that level of reliability, the engine spend over 1,000 hours on the dynamometer. “The long mileage, distributed to many events with short runs, is really tough. Plus, the four-cylinder engine’s vibration behavior totally differs from that of the V8. That posed a huge challenge during the development of the engine and also to our dynamometers. Every engine subsequently runs on the dynamometer for another two to three hours before being installed in the car for racing. We run a break-in program, a performance check and various functional checks,” elaborated Stefan Dreyer, Head of Powertrain Development.
In powertrain and engine development, Audi uses three types of test rigs. On the one-cylinder rig, only one cylinder of the future engine is tested. These single-cylinder tests are focused on the combustion process and friction performance. The fully assembled engine is then developed on the engine dyno, as well as on the suspension test bench, where the new engine and drive system are run as realistically as possible.
The extensive engine testing helped relieve some of the pressure on Audi’s engine specialists, but the chassis designers worries weren’t assuaged by the gains in reliability. They were more concerned with how the bump in power and drop in weight would affect the new car in other areas. After all, the added thrust is expected to reduce lap times by 2-3 seconds, and should yield top speeds nearing 190 miles an hour, so some other tweaks were in order.
The greater speeds place greater demands on the brakes, the cooling system, and so on. To suit these needs, the Audi RS5 DTM’s front end was modified to cool the brakes and reduce the increased engine bay temperatures. The position of the water and oil cooling systems, pipes, and the intercooler also factored into this redesign. A more aggressive front is only part of the change—the front diffuser, rear diffuser, underfloor, and rear wing were all overhauled to suit the new regulations.
The Sound and The Fury
With endless crackling and anti-lag popping during the overrun, as well as the dynamic rasp of the RC8, the soundtrack ought to impress. While it might not scream like the outgoing V8s, some drivers already find the new exhaust note more appealing. “I definitely don’t want to exchange the turbo for the old V8 vacuum cleaner anymore,” remarked Nico Muller.
Though you sometime get the sense that drivers are just shills trying to keep the employer happy, their fanfare seems genuine with this masterpiece of a motor. The agility of the car, the frightening rate of acceleration, and the raucous exhaust note indicate that we have plenty to look forward to with this new formula.
However, only time will tell if this new format will improve the sometimes processional spectacle of DTM. “I’m convinced that we’ll be able to deliver the most spectacular touring car racing of all time to fans and customers,” concluded Dreyer. A bold statement—but one that has a good chance of being correct.