What the BMW B38 Is
The BMW B38 is a 1.5-liter turbocharged inline-three that debuted in 2014 as the smallest member of BMW's modular engine family. Built around a roughly 500cc-per-cylinder architecture shared with the four-cylinder B48 and six-cylinder B58, the B38 pairs efficient displacement with TwinPower Turbo tech—a single twin-scroll turbocharger, direct injection, and Valvetronic variable valve lift. Output ranges from 134 to 228 hp and 162 to 236 lb-ft of torque depending on tune, with a 6,500 rpm redline.
Engineering & Specs
As BMW's first mass-produced three-cylinder, the B38 was engineered for both economy models and, in higher states of tune, genuine sporting duty. Key traits include:
- Displacement: 1.5L (1,499cc), turbocharged inline-three
- Induction: single twin-scroll turbo with direct injection
- Output: 134–228 hp; 162–236 lb-ft torque
- Redline: 6,500 rpm
- Production: 2014–present
The modular design means the B38 shares tooling, bore spacing, and many components with its larger siblings, simplifying manufacturing and parts commonality across BMW's lineup. A counterbalance shaft tames the inherent vibration of the three-cylinder layout, giving the engine surprisingly smooth manners for its configuration.
Which BMWs Used It
In the United States, the B38 is most famous as the combustion engine inside the BMW i8, where its turbocharged three-cylinder drives the rear wheels while an electric motor powers the front—making the i8 a plug-in hybrid sports car. Internationally, the B38 also appears in models such as the 228i Gran Coupe and various front-wheel-drive-based BMWs and MINIs. If you're unsure which engine sits in a given car, run the chassis number through our VIN decoder to confirm the exact fitment.
Ownership & Buying Notes
The B38 is a modern, tightly packaged engine, so routine maintenance discipline matters. As with most direct-injected BMW turbo engines, owners should stay ahead of oil service intervals, watch for carbon buildup over high mileage, and keep an eye on the cooling system and turbocharger plumbing. In the i8, the engine leads an unusual life—running intermittently alongside the electric drivetrain—so verifying service history and battery health together is essential before buying.
Shoppers cross-shopping BMW's modular lineup may also consider the four-cylinder B48 for a more conventional turbocharged experience, or step up to the diesel B57 where offered. For deeper technical context across the family, browse the BMW engine encyclopedia.
Legacy
The B38 proved that a three-cylinder could carry a BMW badge without apology, delivering efficiency, refinement, and—in the i8—real performance credibility. It anchors the small end of the modular family and remains a cornerstone of BMW's downsized, forced-induction engine strategy.