The BMW B38 is a 1.2 and 1.5 L (1,198 and 1,499 cc) turbocharged straight-three DOHC petrol engine, which replaced the straight-four BMW N13. Production started in 2013.

Quick Facts B38 engine, Overview ...

B38 engine
Overview
Manufacturer	BMW
Production	2013–present
Layout
Configuration	straight-3
Displacement	1.2 L (1,198 cc) 1.5 L (1,499 cc)
Cylinder bore	78 mm (3.1 in) 82 mm (3.2 in)
Piston stroke	83.6 mm (3.29 in) 94.6 mm (3.72 in)
Valvetrain	DOHC
Compression ratio	11:1
Combustion
Turbocharger	Single-scroll
Fuel system	Direct injection
Fuel type	Gasoline
Chronology
Predecessor	BMW N13

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It is part of a modular BMW engine family of straight-three (B38), straight-four (B48) and straight-six (B58) alloy block and head petrol engines,^[1] which use a displacement of 400 cc (24.4 cu in) per cylinder in the 1.2 and 500 cc (30.5 cu in) per cylinder in the 1.5. It specifically shares a lot of components with the BMW B37, due to their same size/configuration.

The B38 is used in front-wheel drive cars (such as the Mini Hatch and BMW 2 Series Active Tourer), as well as BMW's traditional rear-wheel drive and all-wheel drive (xDrive) configurations. The first car to use the B38 is the BMW i8 hybrid sports coupé,^[2] where it is used as a transverse mid-mounted engine.^[3]

The B38 features direct injection, an 11:1 compression ratio,^[4] variable valve timing (double-VANOS) and the twin-power turbo turbocharger with the world's first aluminium turbine housing,^[5][6] manufactured by Continental.

On the 1.2 Liter versions, the bore is 78 mm (3.1 in) and the stroke is 83.6 mm (3.3 in). On the 1.5 Liter versions, the bore is 82 mm (3.2 in) and the stroke is 94.6 mm (3.7 in).