Laying quietly under a thin sheet of aluminum is BMW M’s latest technological marvel. Known internally as the S63tu (technical update), this latest M engine is an evolution of the S63 V8 previously employed in the X5 M and X6 M “super-utes.” The basic layout remains familiar, with both the S63 and S63tu sharing the same block, head, and the majority of components. Both engines are twin-turbo, twin-scroll 90° V8 units featuring BMW’s patented cross-bank exhaust headers, continuously variable valve timing on both the intake and exhaust side, and high-precision direct fuel injection.
Where the engines begin to diverge is in the details. The new M5 gains a higher compression ratio of 10:1. In fact, BMW M has made so many changes to the original S63 V8 that they now describe it as a “newly developed” engine. New pistons help achieve the higher compression ratio, while boost pressure has been slightly reduced by 0.1 bar. Larger intercoolers improve cooling capacity, and the turbochargers themselves are new with a larger turbine diameter. A revised valvetrain introduces BMW’s Valvetronic variable valve lift on the intake side. Throttle bodies remain in place, but only serve as a backup in “limp-home” mode. On top of that, BMW has completely revamped the electronic engine management system, optimizing nearly every parameter to deliver a higher redline — now 7,200 rpm.
With all these changes, you might wonder why the new M5 gained only five horsepower over the X5 M and X6 M. The short answer: BMW chose to prioritize efficiency and drivability — particularly throttle response — over sheer peak output. Could M engineers have extracted more power? Absolutely. But as history shows, M cars are not defined by headline horsepower figures alone.
Compared with the previous generation E60 M5, the progress is striking. The new F10 M5 consumes 30% less fuel while producing 10% more power and 30% more torque. That means greater range, fewer fuel stops on long trips, and reduced emissions. On the EU test cycle, the new M5 managed 9.9 liters/100 km (28.5 mpg), with COâ‚‚ emissions down to 232 g/km under EU5 standards.
One of the defining features of the M5’s V8 is its compact layout, placing both turbos and catalytic converters inside the ‘V’ of the 90° cylinder banks. Like too many people on the dance floor, things get pretty cramped and hot in this small space. Engine cooling is therefore critical, and an extremely powerful cooling system — including large intercoolers — has been developed to meet this demand. The front-end aerodynamics have also been sculpted to guide sufficient airflow into the radiators and around the engine and brakes.
Besides its compact design, the placement of the turbos within the ‘V’ of the cylinder banks has one particular benefit: throttle response. As you decrease the distance from the exhaust valves to the turbine blades of the turbo, you reduce the amount of time it takes for the exhaust gases to reach and spin the turbine — which in turn builds intake boost more quickly. Typical turbocharged engines suffer from ‘turbo lag’ — the delay between pressing the throttle and feeling acceleration. BMW M’s design solution nearly eliminates perceptible lag. It’s that good. (For a more in-depth look at turbocharging technology, check our previous tech feature.)
Also reducing turbo lag is BMW’s patented cross-bank exhaust manifold. Each cylinder bank of four cylinders donates exhaust gases from one of its cylinders to one scroll of one turbo. Therefore, both scrolls of both turbos have two dedicated cylinders feeding them at all times — but the magic lies in the pairing. Based on the firing order of the V8 across both banks of cylinders, an exhaust pulse is evenly distributed to both scrolls of both turbos, keeping them spooled across the entire RPM range. On paper it sounds impressive, in practice it’s staggering. And the sound is equally special: the unique routing of each cylinder creates a distinct, exotic tone that adds to the M5’s supercar appeal.
The new M5 has so little throttle lag that you might as well say it has none, at least within the realm of turbocharged engines. Physics dictates that lag can’t be eliminated entirely, but from behind the wheel it’s nearly imperceptible. Only in higher gears do you notice a slight disconnect between the gas pedal and the rear wheels. After driving the M5, I can confidently say the new turbo V8 feels nearly “lag free” — and that’s a bold statement. Throttle response is sharp enough to allow for throttle steering and drifting through tight corners, which is the ultimate compliment for a turbocharged M engine.
I’ve spent plenty of time lapping BMW’s X6 M, and I’ve always been impressed with its quick throttle response. But the M5’s engine takes it a step further — closing the gap to perfection. Where the X6 M makes you wait for the power to swell, in the M5 it’s simply there, always ready to thrill, to break the rear tires loose in a tail-out slide, or to stretch your smile wide as it pins you to the seat.
BMW’s previous M5, the E60, was impressive in its own right. Its V10 revved to a stratospheric 8,250 rpm and delivered 507 horsepower. But there’s a key difference between that high-strung ten-cylinder and the new turbocharged V8: drivability. The V10 needed revs to unleash its power — it didn’t deliver peak torque until well past 4,000 rpm. The new M5’s V8 is different. It develops 100% of its torque at just 1,500 rpm, which makes for explosive low-end response. Even more remarkable, that torque holds steady all the way to 5,750 rpm before tapering off toward redline — yet it still delivers nearly 400 lb-ft at 7,200 rpm. In fact, this engine produces 405 lb-ft of torque just above idle. Parking valets, take note.
So while it’s true that the new M5 doesn’t rev as high as its predecessor — peaking around 1,000 rpm lower — its powerband is roughly three times wider. And that says it all. As the saying goes: “horsepower sells cars, torque wins races.”
Maximum horsepower also finds a wide plateau between 6,000 and 7,000 rpm. A robust 560 horsepower flows to the crankshaft, tapering only slightly before the 7,200 rpm redline. On paper, dynographs show the drop-off — but from the driver’s seat, it’s impossible to detect.
The new turbo V8 is a marvel of modern engineering; a masterpiece best appreciated not on spec sheets but out on the racetrack. On that note, stay tuned for our upcoming racetrack review of the new M5, to be published soon. A full BMWBLOG First Drive review is also on the way.
(Photos Credit: Daniel Kraus, Shawn Molnar)
