Audi’s new engine produces 239kW per litre

Audi has a new most powerful engine, and it’s all thanks to the world of motorsport.

DTM, Germany’s top flight motorsport series, has changed to ‘Class 1’ regulations for 2019, bringing it in line with Super GT’s GT500 class in Japan.

The new regulations brought with them a bevy of changes, with larger, yet simpler, aerodynamics, and most importantly, a change from 4.0-litre V8 engines to turbocharged four-cylinders.

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While the aural delight of the atmo bent-eight has disappeared, its replacement has made up for the loss with fire-breathing power outputs.

Audi claims its newly developed 2.0-litre four-cylinder turbo is capable of 454kW, an increase of 74kW compared to the 2018 DTM car – from half the cylinders.

However, that’s not the new engine’s outright peak power figure, with the rules allowing for a ‘push-to-pass’ function which gives drivers access to an additional 23kW for a limited amount of time, briefly boosting outputs to 477kW.

Currently, the most powerful engine fitted to an Audi is nestled under the R8 V10 plus coupe’s rear cowl, with the naturally-aspirated 5.0-litre V10 producing 449kW and 560Nm.

Audi’s other racing engines can’t even compare, with the R8 GT3 LMS producing between 365kW and 412kW depending on BoP restrictions, and the S1 EKS RX quattro rallycross car reportedly producing 426kW and 700Nm last year before it was stripped of factory support.

Head of Engine Development at Audi Motorsport Ulrich Baretzky suggested even more power could have been created if fuel-flow restrictions were lifted.

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Current rules dictate a fuel-flow of 95 kilograms per hour, and the tech that Audi has implemented to meet this restriction could flow into road cars in the near future.

“That may sound like a lot but, in view of more than 610 horsepower, it really isn’t,” Baretzky said.

“The specific consumption of the DTM engine is extremely low and now within ranges that used to be typical for diesel engines.

“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.”

Not only is it more powerful than the outgoing V8, it is also 50 percent lighter at just 85 kilograms, dropping the RS5 DTM car’s dry weight to under 1000kg, with a power-to-weight ratio of 2.1kW per tonne.

The engine must also last the full season, so is designed to survive 6000 punishing kilometres of racing.

Putting Audi’s creation into perspective, ponder this: Cosworth’s latest creation is a 6.5-litre naturally-aspirated V12 that has a sound so visceral, journalists had to be warned before they heard it come to life. Destined to be fitted to Aston Martin’s Valkyrie hypercar, it’s essentially a racing engine that someone saw fit to sell to the public, and it produces - wait for it - 735kW.

However, in terms of power density, it’s nothing on the Audi four-pot, with just 113kW per litre.

The most powerful 2.0-litre engine the general public can buy is Mercedes-AMG’s M113, which is fitted to its 45-badged products, producing 280kW (140kW per litre). Rumours suggest this will jump to 309kW thanks to extensive re-engineering for the 2020 A45 AMG.

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Back in the world of motorsport, Porsche’s 2.0-litre turbocharged V4 which was fitted to the 919 produced “just under” 368kW during LMP1’s fuel-flow restricted era. When unleashed from regulations, this grew to 530kW.

But, in terms of power density, there is one engine that stands above the rest - the BMW M12/13 1.5-litre four-cylinder from Formula 1’s ‘80s era.

With a single KKK turbo and Bosch digital electronic management system, the M12/13 was allegedly capable of 1044kW, or a staggering 696kW per litre, in 1986 qualifying trim.

There’s almost an entire book to be written on the M12/13, which was built using a production-based block, and its fabled power outputs will forever remain surrounded in mirth and mystery because the dyno BMW used to measure power couldn’t record figures above 954kW.

While Audi’s new unit is unlikely to threaten the M12/13’s crown, even when unleashed from regulations, it does hint at the brand’s ability to produce low-capacity, high-power monsters to add to its road fleet in the near future.