BMW TwinPower Turbo Engines Explained

The Munich-based manufacturer started to embrace turbocharging in the 1970s with the series-production 2002 turbo and the E25 Turbo concept that paved the way for the naturally aspirated six-cylinder M1. A decade later, BMW rolled out the M21 inline-six turbo diesel.

2006 was the year of the twin-turbo N54, which is BMW's first mass-produced turbocharged gasoline engine. Retroactively bestowed with the TwinPower Turbo title, said inline-six rocks two snails. At the time, the problem with calling the N54 a member of the TwinPower Turbo family was the N55, which uses a single twin-scroll turbo rather than two mono-scroll units.

The twin in twin-scroll turbo refers to two exhaust gas streams instead of one for the mono-scroll design. Back in 2009, the BMW 535i Gran Turismo was the first series-production automobile to use the N55 single-turbo I6. As such, TwinPower Turbo was born in 2009 with the N55 rather than 2006 with the N54.

TwinPower Turbo further indicates solenoid-type direct fuel injectors, while the N54 used piezo direct injectors throughout its production life cycle. Adding to the confusion, TwinPower Turbo diesel engines use common rail direct injection. TwinPower Turbo also incorporates Valvetronic variable valve lift and double VANOS variable valve timing technologies.

In short, TwinPower Turbo designates a turbocharged engine with direct fuel injection, Valvetronic, and double VANOS. On the turbocharging side, TwinPower Turbo currently stands for a single mono- or twin-scroll turbo, a parallel setup (two similarly sized snails), and sequential turbos (differently sized snails).

That said, let's go through all TwinPower Turbo engines after the number of cylinders they have. To keep it nice and tidy, we'll kick this off with the B37 three-pot diesel and the B38 gasser.

BMW TwinPower Turbo three-cylinder engines

Gifted with a mono-scroll turbocharger with variable turbine geometry, the B37 came out in 2014 in the MINI One D, the punchier Cooper D, and the BMW 216d Active Tourer. Its 1.5-liter displacement results from an 84-millimeter cylinder bore and a 90-millimeter piston stroke.

The lowly B37, along with the four-pot B47 and the six-cylinder B57, are closely related by means of a modular cylinder specification (just over 498 millimeters) and the rear-mounted timing chain. All three feature on-demand electric water pumps, balancer shafts for improved smoothness, and forged steel for the crank and the conrods.

Originally, the B37 produced 95 pferdestarke at 4,000 revolutions per minute and 220 newton meters at 1,750 revolutions per minute in the MINI ONE D, figures that convert to 94 horsepower and 162 pound-feet of torque. In the Cooper D and 216d Active Tourer, the ratings were 116 ps (114 hp) and 270 Nm (199 lb-ft).

Moving on to the B38, the gas-fueled sibling spawned 1.2- and 1.5-liter units. The former was used exclusively by the MINI One, whereas the 1.5 can be found in the 2018 MINI One, Countryman, Clubman, the BMW 116i, the 216i Active Tourer and Gran Tourer, 18i models, the 225xe Active Tourer, and the X2 xDrive25e. This fellow also flaunts a single-scroll turbocharger.

Codenamed B38A12U0, the lesser powerplant develops either 75 ps (74 hp) and 150 Nm (111 lb-ft) or 102 ps (101 hp) and 180 Nm (133 lb-ft). For the B38A15 series, output figures top 170 ps (168 hp) and 280 Nm (207 lb-ft) with mild-hybrid assistance. In this application, 48-volt assistance comprises a dual-clutch transmission with a small electric motor, which acts as a starter generator.

The B38K15 saw only two applications in the form of the Karma Revero GT and the BMW i8. In the latter, it's good for 231 ps (228 hp) at 5,800 revolutions per minute and 320 Nm (236 lb-ft) at 3,700 revolutions per minute. As for the Revero GT and later models, the B38K15 powers a generator that charges the high-voltage battery.

BMW TwinPower Turbo four-cylinder engines

N20 opens the list of TwinPower Turbo lumps packing four pots, with said N20 coming in 1.6- and 2.0-liter flavors. Twin-scroll turbocharging is used across the board, which applies to its heir apparent as well. But more on the B48 later.

The successor to the free-breathing N52 and N53 six-cylinder engines would become notorious for timing chain guide failures caused by substandard polycarbonate compositions. N20 production concluded in 2017, with the most interesting member of the bunch cranking out 245 ps (241 hp) at 5,000 rpm and 350 Nm (258 lb-ft) at 1,250 all the way to 4,800 revolutions per minute.

A more undersquare design with a closed-deck block, the B48 is much superior to its forerunner. Also available in two displacements, the four-cylinder turbo gasser can be found in 18i, 25i, 28i, 30i, 30e, 35i, and 40e models, along with the JCW and JCW GP from the folks at MINI. Priced at $49,900 for the 2024 model year, the X1 M35i for the US market features the B48 with 312 ponies and 295 pound-feet (400 Nm) on tap.

Offered from 2007 through 2014 with either 1.6 or 2.0 liters to its name, the N47 is yet another TwinPower Turbo engine that wasn't called TwinPower Turbo at launch. Similar to the B37, it runs a 16.5:1 compression ratio. And similar to the N20, it suffered from timing chain issues. Other notable problems include turbo wastegate return spring failure and engine fires caused by EGR cooler bypass valve vacuum hose failure.

Used in the E87 1 Series, E90 3 Series, E60 5 Series, as well as the X1 and X3 from that era, the N47 grew an extra turbocharger in October 2007, thus becoming the first series-production turbo diesel to belt out more than 100 horses per liter. At most, it develops 215 horsepower at 4,400 rpm and 332 pound-feet (450 Nm) at 2,500 rpm.

Despite being a decade old at the moment of writing this piece, the succeeding B47 soldiers on with single- and twin-turbo arrangements. The 2.0-liter mill received selective catalytic reduction with the B47TU1 technical update from late 2017, along with slightly higher injection pressures. In November 2019, it became a mild hybrid with the addition of a 48-volt system and a starter generator. Because diesels are all about torque, we'll end this segment with the highest peak torque rating available, that being 295 pound-feet (500 Nm) at only 1,500 rpm.

BMW TwinPower Turbo six-cylinder engines

BMW is synonymous with the straight-six, and the N54 was a darn good engine. So good, it won the International Engine of the Year award no fewer than six times during its 2006 to 2016 tenure. This powerplant was also used in the limited-edition 1 Series M Coupe, though it wouldn't be the only non-M sixer to be used in an M vehicle. Remember the original M2?

It churns out a respectable 365 horsepower and 343 pound-feet (465 Nm) from the N55B30T0. Thankfully, the M2 Competition and M2 CS used the S55 with outputs ranging from 405 to 444 horsepower and 550 Nm (406 pound-feet).

The N55 and S55 were replaced by the far more capable B58 and S58, with the M-specific engine developing as much as 553 horsepower in the M4-based 3.0 CSL. At the other end of the spectrum, the B58 of the 540i nets 375 horsepower compared to 386 for the M340i. Also worthy of note, this B58 single-turbo sixer can be found in the Magna Steyr-produced Toyota GR Supra 3.0, which is rated at 382 ponies.

Over in diesel realm, the N57 jointly replaced the M57 straight-six and M67 vee-eight. Just like the N54 of 2006, this one also features a piezo fuel injection system. Torque ratings vary like crazy because the N57 engine family comprised single-, twin-, and tri-turbo diesels with the internal codenames N57D30Ox, N57D30Tx, and N57S.

The S saw action from 2012 through 2018 in the M550d, 750d, as well as the X5 and X6 M50d. While 375 horses may not be a lot in a heavy rear-biased vehicle, 546 pound-feet (740 Nm) at 2,000 to 3,000 revolutions per minute is more than enough for said vehicle to feel adequately quick.

How did BMW improve on this crazy tri-turbo diesel? With a quad-turbo unit, of course! Enter the B57D30S0, which ended production in 2020 with 394 horsepower and 760 Nm (560 pound-feet) on deck. Like its predecessor, applications included the M550d, 750d, X5 and X6 M50d, plus the X7 M50d three-row sport utility vehicle.

BMW TwinPower Turbo eight-cylinder engines

BMW started manufacturing V8s in 1954. A direct replacement for the overhead-valve original would have to wait until 1992 with the M60, a 90-degree unit that was succeeded by the M62 and N62. Turbocharging became the norm with the N63 of 2008, with BMW placing the mono-scroll turbos inside the engine's vee.

The second technical update saw the N63 getting twin-scroll turbos, and the third technical update enabled the M division's most powerful S63 to date. Said engine develops 626 horsepower and 553 pound-feet (750 Nm) of tire-shredding torque in the F90-generation BMW M5 CS. Starting with the X7 M60i, which is an M Performance model rather than a blue-blooded M, the S68 began replacing the S63 in the lineup.

Despite sharing its displacement with the S63, this lump is different in certain respects. Highlights include a new crank, electric instead of hydraulic VANOS, and provisions for mild- and plug-in hybrid setups. The XM Label and M5 are its most powerful applications as of 2024, with the XM Label boasting a combined 738 horsepower and 738 pound-feet (1,000 Nm) versus 717 horsepower and similar peak torque for the G90-series M5. On its own, the S68 has been tuned to 631 horses and 590 pound-feet (800 Nm) by Alpina for the X7 M60i-based XB7.

BMW TwinPower Turbo twelve-cylinder engines

Had it been developed with provisions for turbocharging, the N73 would've been the first BMW-developed V12 engine to meet the TwinPower Turbo criteria. However, forced induction had to wait until the N74 showed up in 2009. There is a reason why we've mentioned the N73 before the N74, for it the older design features Valvetronic while the N74 does not.

The lack of Valvetronic variable valve lift does not qualify the N74 for the TwinPower Turbo designation, but who cares anyway? Time and again, BMW proved that TwinPower Turbo is – at best – a marketing gimmick that rivals the ambiguity of EfficientDynamics. Truth be told, a twin-turbocharged version of the N73 would be much worthier of the TwinPower Turbo label.

ZF's acclaimed 8HP torque-converter automatic made its debut in two BMWs fitted with the N74, those vehicles being the F01 760i and F02 760Li. The N74 disappeared from the BMW lineup after the G12 M760Li went out of production in 2022 in favor of a mild-hybrid V8 stateside and a plug-in hybrid I6 for Europe. Only the Rolls-Royce brand continues to use this torque monster, with the Ghost Black Badge sedan and the Cullinan Black Badge utility vehicle netting 664 pound-feet (900 Nm). As for maximum power, the Wraith tops out at 624 mechanical ponies.