BMW B38 Engine Guide

B38 · 1,498 cc · turbocharged three-cylinder · US-market BMW: i8 only, built 04/2014-11/2019 (I12 coupe, facelift coupe and I15 roadster)

The B38 is BMW's 1.5 liter three-cylinder turbocharged petrol engine. BMW's service data gives its displacement as 1,498 cc, and BMW's 2013 i8 press kit announced it as a debut for a three-cylinder petrol engine with TwinPower Turbo technology. BMW and MINI also used the B38 in other models sold outside the United States, so this page says which statement applies to which car.

The i8 is the only BMW-badged car in BMW's US parts data that carries a B38-family engine. MINI also sold B38-powered cars in the US, but they are not covered here.

Quick read

• Ownership position: Not established yet. We are still researching this engine.
• Reliability: Not established yet. NHTSA lists recalls on the i8 but none of them describes the engine.
• Cost to own: Not established yet. We are still researching this engine.
• Power potential: Not established yet. BMW lists 170 kW (231 hp) for the i8 engine.
• Main watch item: None established from a BMW document. BMW has a service bulletin on a special tool for installing the i8 coolant thermostat.

B38 At a Glance

Question	Practical answer
US-market BMW cars	i8 only, in BMW's parts data to December 2019: I12 coupe, I12 facelift coupe and I15 roadster.
Layout	Three cylinders, 1.5 liters, one exhaust turbocharger, direct injection.
i8 engine output	170 kW (231 hp) and 320 Nm (236 lb-ft) in BMW's 2013 press kit.
Engine oil, i8	4.5 US quarts (4.25 liters). BMW's February 2017 bulletin lists 0W-30 LL01FE for model years 2012-2015 and 0W-20 LL14FE+ for model year 2016 and newer.
Reliability profile	Not established yet.
Typical annual planning budget	Not established yet.
Common tuned street range	Not established yet.
Before buying	Confirm the exact car and build date, and ask a BMW dealer to check the VIN for open recalls.

Where you find it

The table lists the US-market BMW cars first, then BMW cars sold in other markets. US-market dates are build months from parts-level fitment rows. Dates for other markets are catalog dates from BMW's vehicle-type lists, not production claims. All of it comes from BMW's parts data, which ends in December 2019, so later builds are not established. MINI cars are left out.

Market	Chassis and models	Engine code in BMW data	Built (US) or catalog dates (other markets)
US	I12 i8 Coupe	B38	4/2014-10/2017
US	I12 facelift i8 Coupe	B38X	3/2018-11/2019
US	I15 i8 Roadster	B38X	3/2018-11/2019
Other markets	F20 and F21 116i and 118i (facelift cars)	B38	5/2014-6/2019
Other markets	F22 and F23 218i	B38	6/2014-12/2019
Other markets	F30 and F31 318i (facelift cars)	B38	3/2015-10/2018 (F30) and 1/2015-6/2019 (F31)
Other markets	F32 and F36 418i	B38	5/2014-12/2019
Other markets	F45 216i, 218i and 225xe	B38, B38B, B38C and B38X (225xe)	11/2013-12/2019
Other markets	F46 216i and 218i	B38, B38B and B38C	7/2014-12/2019
Other markets	F48 X1 18i	B38 and B38C	11/2014-12/2019
Other markets	F39 X2 18i	B38C	3/2017-12/2019
Other markets	F40 118i	B38C	5/2018-12/2019
Other markets	F44 218i Gran Coupe	B38C	10/2018-12/2019

BMW's parts data also lists B38-family engines in cars for China, Malaysia, Thailand, Indonesia, Egypt and Russia; those are not broken out here.

The i3 with range extender does not use a B38: BMW's February 2017 oil chart lists its range extender engine as the W20.

Technical Specifications

Specification	Detail
Cylinders	3
Displacement, bore and stroke	1.5 liter: 1,498 cc, 82 mm bore and 94.6 mm stroke (BMW's US press kit prints 1,499 cc). BMW's data also lists a 1.2 liter version: 1,197 cc, 78 mm bore and 83.6 mm stroke.
Compression ratio	1.5 liter, 170 kW version: 9.5:1. 1.5 liter, 150 kW version: 10.2:1. 1.2 liter: 10.2:1.
Output, i8 engine	170 kW (231 hp), 320 Nm (236 lb-ft). BMW's US press kit prints both 228 hp and 231 hp for the same 170 kW.
Output, i8 with electric motor	266 kW (357 hp) and 570 Nm (420 lb-ft) in the 2013 press kit. BMW's service data later gives 275 kW (374 hp) and 570 Nm for the updated car.
Valve head diameter	28.4 mm intake and 27.1 mm exhaust
Valve control	BMW's US press kit describes VALVETRONIC throttle-less load control for the i8 engine. BMW's i8 service description lists a coolant-cooled throttle valve in the intake system. We have not resolved how the two descriptions fit together.
Fuel system	Direct injection, up to 200 bar. The exhaust camshaft drives the high pressure pump, and the injectors mount directly on the rail, with no separate high pressure lines to them.
Turbocharger	One exhaust turbocharger of conventional design, with no variable turbine geometry and no twin-scroll housing. The steel exhaust manifold is part of the turbine housing, and boost is controlled by an electric wastegate.
Charge air	Indirect charge air cooling: a coolant-cooled heat exchanger sits in the intake manifold.
Belt drive	Eight-rib belt, driven with a high-voltage starter generator in place of a conventional starter motor (i8).
Engine oil capacity, i8	4.5 US quarts (4.25 liters)
Engine oil grade	0W-30 LL01FE (model years 2012-2015) and 0W-20 LL14FE+ (model year 2016 and newer), per BMW's February 2017 bulletin. BMW's December 2015 oil bulletin names the i8 (I12, B38) for 0W-20 LL-14 FE+ from model year 2016.
Coolant capacity, firing order	Not established yet.

Factory Deep Dive

Block and head

The 1.5 liter engine uses an 82 mm bore, 94.6 mm stroke and 1,498 cc displacement. BMW's repair documentation lists a gear for a counterbalance shaft on the B38, with separate entries for the O0 and T0 versions. The i8 engine code is B38K15T0, and BMW describes it as based on the earlier B38 engines.

Valvetrain

BMW's service documents for the B38 refer to a Valvetronic servomotor and to VANOS adjusters and central valves on the i8 (I12). The valve head diameters are 28.4 mm intake and 27.1 mm exhaust. The open question about a throttle valve on the i8 engine is explained in the Specifications table above.

Fuel and induction

BMW describes the i8 intake as an all-new design with a two-part untreated air intake: one duct is chosen for power and another for acoustics, and a flap closes the intake between 3,000 and 4,500 rpm. Fuel goes in at up to 200 bar.

Cooling

The i8 has two separate coolant circuits, one high-temperature and one low-temperature. The low-temperature circuit cools the throttle valve, the charge air heat exchanger, the starter generator and the electronics. A map-controlled thermostat and a coolant pump sit in the high-temperature circuit, and the combustion engine also has a mechanical coolant pump.

Variants

BMW's data separates the 1.2 liter and 1.5 liter B38, and splits the 1.5 liter into 170 kW and 150 kW versions by compression ratio. The 170 kW engine is the one in the i8. BMW's parts data uses the code B38X for the i8 facelift and roadster, the 225xe and the US MINI Cooper SE ALL4, and B38B and B38C for later cars sold outside the US.

Service Parts at a Glance

Each number below is the current BMW number in BMW's parts data (December 2019) and is listed there for the US-market i8.

Part	BMW part number (current)	Note
Oil filter	11 42 8 585 235	Replaces 11 42 8 511 391 (discontinued 08/2014). One per engine.
Oil filter element set	11 42 8 570 590	Listed for the i8 as well.
Spark plug	12 12 2 455 258	Three per engine. Replaces 12 12 0 046 646 (discontinued 04/2019).
Ignition coil	12 13 8 643 360	Three per engine. The chain runs 12 13 7 619 385, 12 13 8 647 463, 12 13 8 678 438, 12 13 8 615 991, then 12 13 8 643 360.
Air filter element	13 71 7 634 154	One per engine.
Coolant pump with thermostat	11 51 7 643 930	Replaces 11 51 8 623 582 and 11 51 2 381 368 (both discontinued 10/2016).
Cylinder head cover	11 23 8 678 432	Replaces 11 12 2 404 440 (discontinued 03/2017).
Timing chain	11 31 8 648 729	Replaces 11 31 7 617 488 (discontinued 02/2016).
High pressure pump	13 51 7 636 881	Replaces 13 51 8 621 083 (discontinued 07/2018).
Turbocharger with exhaust manifold	11 65 7 625 161	Replaces 11 65 8 643 131 and 11 65 2 400 536.

BMW's oil filter, spark plug, ignition coil and timing chain numbers above also fit other BMW and MINI engines (B46, B48, B58 and others), so confirm the exact car before ordering.

Known Failure Points and Service Items

No BMW document read for this guide describes a recurring B38 engine fault, and no NHTSA recall found for the i8 is about the engine itself. Two items are documented.

01 Coolant thermostat installation on the i8

BMW service information 01 09 15 (244) introduces a special tool for fitting the coolant thermostat on the i8 (I12, engine B38K15T0); BMW supplies the tool only to order. Watch for: the bulletin does not describe a symptom, and no failure rate is established.

02 Vehicle recalls on the i8 that do not concern the engine

NHTSA lists the recalls below for the i8. None of them is about the B38 engine.

• 14V674000: model year 2014 i8 built from May 16, 2014 to September 16, 2014. A bolt that attaches a ground cable between the tank and the chassis may not have been welded properly, which NHTSA says could cause a fuel leak.
• 15V882000: model year 2015 i8 built May 29, 2015 to June 5, 2015. Improperly drilled holes in the stability control hydraulic unit may restrict pistons and impair braking.
• 16V914000: model year 2017 i8, among many other BMW and MINI models. Seat-mounted side air bag inflator initiators may fail to ignite in a crash, so the air bag would not deploy.
• 18V652000: 2019 i8 and i8 Roadster, among other BMW models. Capacitors in the TurboCord portable charger may fail, which NHTSA says could cause a shock hazard or fire.
• 19V599000: certain 2019 i8 vehicles. A circuit board problem in the electric motor electronics may shut down the high-voltage supply, which NHTSA says would cause a loss of propulsion.
• 20V601000: 2020 i8, among other models. Debris may have entered hybrid battery cells during production, which NHTSA says could cause a short circuit.

Sources: NHTSA recall data, i8 2014, 2015, 2017, 2019, 2020. Ask a BMW dealer to check your VIN for open recalls.

Reliability Verdict

Not established yet. We are still researching this engine.

Power Potential

Not established yet. We are still researching this engine. BMW's published figure for the i8 engine is 170 kW (231 hp).

Cost of Ownership

Not established yet. We are still researching this engine.

Common Questions

What is the BMW B38 engine?

The B38 is BMW's 1.5 liter turbocharged three-cylinder petrol engine, with an 82 mm bore, a 94.6 mm stroke and a displacement of 1,498 cc in BMW's service data.

Which BMW sold in the US has the B38?

In BMW's parts data to December 2019, the only BMW-badged US-market car with a B38-family engine is the i8, as the I12 coupe, the facelift coupe and the I15 roadster.

How much oil does the i8 engine take?

BMW's February 2017 oil bulletin lists 4.5 US quarts (4.25 liters) for the i8 with the B38.

How much power does the B38 make in the i8?

BMW's 2013 press kit gives the i8's three-cylinder engine 170 kW (231 hp) and 320 Nm (236 lb-ft), with 266 kW (357 hp) combined with the electric motor at launch.

Does the i3 REx use the B38?

No. BMW's February 2017 oil chart lists the i3 range extender engine as the W20, not the B38.

Sources

• BMW Group PressClub, The BMW i8, 10 September 2013.
• BMW Group PressClub USA, The BMW i8, priced from 135,700 dollars in the US, 10 September 2013.
• BMW of North America service bulletin SI B11 01 15, Engine Oil Quick Reference Chart and Drain Plug Torque, February 2017 revision, as posted by NHTSA.
• BMW of North America service bulletin SI B11 01 15, December 2015 revision, as posted by NHTSA.
• NHTSA recall data for the BMW i8, model years 2014, 2015, 2017, 2019 and 2020.
• BMW technical data and service information (engine data, the i8 engine description and the thermostat tool bulletin) and BMW parts catalog data dated 12 December 2019, reviewed internally.