All of the German big three, Audi, BMW and Mercedes-Benz, each have their own big twin-turbo V8 that they pump out in a variety of different high-performance cars. Each company’s has unique attributes that make theirs special, but they’re all pretty great engines that make a lot of power. So let’s take a look at how they stack up against each other. The kind folks at BimmerBoost have gathered some data and made some nice charts to demonstrate the differences of each engine.
Audi has, in recent years, been using a 4.0 liter TFSI twin-turbo V8 in cars like the S6/RS6, S7/RS7 and the S8. This engine has proved very powerful , very smooth and highly efficient, being one of the better high-performance V8’s on the market. It uses twin-scroll turbochargers on all RS models, while the standard S models get single-scroll turbos. The 4.0 TFSI features two top-mounted turbochargers, mounted inside of the vee of the engine, variable valve timing and direct injection. It’s a highly sophisticated engine that, despite being the smallest of them all, develops just as much power as the bigger engines in its class. The 4.0 TFSI, in RS7 guise, produces a peak 32 hp around 6,000 rpm and 511 lb-ft of torque at around 4,000 rpm, though the majority of the torque comes in at a tick over 2,000 rpm.
BMWs famous S63TU engine, the 4.4 liter twin-turbo V8 that BMW has used in nearly all of its big performance cars for years now, is a serious contender. The S63 also has top-mounted twin-scroll turbocharger mounted in the vee of the engine and also features variable valve timing and direct injection. The BMW and Audi engines are remarkably similar, in terms of design and power. In M5 guise, the S63 produces 547 peak hp at a touch over 6,000 rpm and its torque peaks at 504 lb-ft very early at just under 2,000 rpm. So the BMW makes more horsepower but less torque than the Audi 4.0 TFSI, though its peak torque does come in a bit sooner.
The Mercedes-Benz M157 is getting a bit old, but is still being used in most of Mercedes’ bigger AMG models. The M157 is a 5.5 liter twin-turbo V8, though it doesn’t have its turbos mounted in the vee nor does it have twin-scroll turbos. So it’s a bit old school, especially considering it having the biggest displacement of the bunch. This gives the E63 AMG a more linear powerband, with torque and horsepower seemingly coming in smoother, though it does develop a lot less power and falls flat at its 6,250 rpm redline, while the Audi and BMW keep on going a bit longer. The Merc’s M157 makes 458 hp at around 5,500 rpm and peak torque of 465 lb-ft comes in at around 3,000 rpm. Admittedly, Mercedes has developed a 4.0 liter twin-turbo V8 with all of the same new-age tech that the Audi and BMW have, but at the moment is in smaller cars and makes less horsepower, like the C63 AMG.
So while Audi and BMW are almost neck and neck with their two big V8’s, Mercedes seems to be lagging behind a bit. The BMW might be a bit more powerful, but the Audi’s got more torque and it comes in a bit sooner, while the Benz is a distant third in terms of both. The one advantage the Merc might have is the noise, however, as the M157 sounds excellent. Not that the other two don’t, but the big Benz’s all sound just a bit better. All three are excellent engines, develop an incredible amount of power and are all incredibly smooth. If I’d have to give a victory to just one, though, it’s have to be the Audi 4.0 TFSI over the BMW S63TU by the slightest of margins. The only things to give the Audi 4.0 TFSI the win are its smaller, more compact size and slightly better fuel economy. Other than that, these two are the best big German engines you can currently buy.
Photos and Chart from BimmerBoost