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BMW B48 Engine: Specs, Design, Reliability & More

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Last Updated on: 28th November 2023, 12:26 am

The BMW B48 engine is a turbocharged 2.0-liter inline-4 petrol unit, part of BMW’s B-series modular family of engines.

Its power output ranges from 154 to 302 horsepower, with torque figures from 250 to 450 Newton-meters, varying across different versions.

This engine shares its core architectural principles with its larger sibling, the 6-cylinder B58 engine, albeit with two fewer cylinders.

The B48 serves as the evolutionary successor to BMW’s earlier 2.0L turbocharged N20 engine.

Vehicle Applications

The B48 engine typically appears in BMW models bearing the suffixes 20i, 25i, 28i, and 30i.

In some 2019 and later models designated as 35i, a higher-output variant of the B48 is used.

Beyond BMW’s lineup, this engine is also used in certain Mini models and also as an option on the fifth-generation Toyota Supra.

BMW B48 engine

Specs

  • Manufacturer: BMW
  • Production: 2014-present
  • Configuration: Inline-four cylinder
  • Displacement: 1,998 cc (122 cu in)
  • Bore: 82.0 mm (3.23 in)
  • Stroke: 94.6 mm (3.72 in)
  • Valvetrain: DOHC
  • Timing drive: Chain
  • Compression ratio: 11:1
  • Turbocharger: Single, twin-scroll
  • Fuel system: Direct injection
  • Fuel type: Petrol
  • Predecessor: BMW N20
  • Engine oil capacity: 5.25 liters (5.55 quarts)
  • Recommended engine oil: 0W-20, 0W-30, 5W-20, 5W-30
  • Engine oil change interval: 10,000 miles / once a year
  • Spark plug replacement interval: 40,000-60,000 miles
  • Ignition coil replacement interval: 70,000-90,000 miles

Design of the B48

The BMW B48 engine exhibits a more under-square configuration compared to its N20 predecessor.

Like the N20, it features a block and head made of aluminium.

This engine also inherits several key technologies from the N20, including:

  • a twin-scroll turbocharger
  • direct fuel injection
  • Valvetronic variable valve lift system
  • Dual VANOS variable valve timing

The B48 belongs to BMW’s versatile modular engine family, which encompasses various configurations: 3-cylinder (B38/B37), 4-cylinder (B48/B47), and 6-cylinder (B58) engines.

A characteristic trait of this family is the uniform displacement of 500 cubic centimeters per cylinder.

In certain applications, these engines are paired with an electric motor, forming hybrid powertrains. This combination enhances both power and torque.

Stock Performance

The BMW B48 engine, right out of the factory, delivers remarkable performance for a 2.0L 4-cylinder engine.

It produces between 248 and 305 horsepower, placing it among the top-performing engines of its size and displacement.

The B48 demonstrates a smooth and predictable power delivery, aligning with what BMWs stock engines are known for; smooth and predictable power.

The engine’s performance characteristics are notable:

  • Peak torque is achieved at approximately 2,400 rpm and remains remarkably consistent until about 5,000 rpm.
  • Peak power is reached near 5,000 rpm, just as the torque begins to taper off, and maintains stability through to the redline.

The B48’s immediate torque response can be credited to its twin-power turbo technology, which allows for quicker spooling and enhanced low-end torque compared to traditional twin-turbo setups.

While BMW’s current lineup includes more powerful engines, like the B58, the B48 still provides a substantial level of performance in its standard configuration.

The 2.0L inline-4 B48 engine also performs very well when paired with performance modifications and upgrades.

Reliability & Issues

The BMW B48 engine has established a reputation for good reliability.

However, being a relatively recent addition to BMW’s engine lineup, its long-term reliability remains to be seen.

The general trend in BMW’s reliability appears to be on an upward trajectory, especially when comparing the B48 and the B58, to older BMW engines like the N54, N55, N63, and S65.

These newer engines are known for their improved reliability.

Additionally, the B48’s reliability is further endorsed by Toyota’s decision to use it in their Supra models.

The BMW B48 engine appears to be relatively free of widespread issues, with the notable exception of some instances of coolant loss.

Beyond this, the engine does not exhibit a high frequency of failures.

However, as the engine surpasses the 100,000-mile mark, certain components like the cooling system, valve covers, and oil pan gaskets might become more prone to problems.

Some issues that could arise include the following.

1. Valve Cover Leaks

Valve cover gasket leaks, a common issue in BMW engines, also affect the B48.

These leaks primarily arise due to the engine’s high operating temperatures and the use of rubber/polymer gaskets sealing the cylinder head and valve cover.

Typically, valve cover gaskets begin to leak around the 80,000 to 100,000-mile mark.

However, replacing a B48 valve cover gasket can be costly, requiring specialised tools and the removal of various engine components.

As B48 engines age, valve cover gasket leaks are likely to become more common.

2. Oil Filter Housing Cracks

At higher mileages, several B48 owners have encountered issues with their oil filter housing cracking, leading to significant coolant loss or contamination of the engine oil.

The primary culprit behind this problem is the material to construct the oil filter housing is plastic.

Although metal oil filter housings are available from aftermarket suppliers, the quality of the internal O-rings in these non-OEM options can be unreliable.

Typically, failures of the oil filter housing appear between 70,000 and 100,000 miles.

While some failures result in coolant loss, others exhibit signs like:

  • overheating
  • a noticeable odor of oil mixing with coolant
  • the vehicle entering limp mode
  • triggering diagnostic codes

3. Cylinder Head Ventilation Line Issue

In April 2022, BMW issued a technical service bulletin addressing a significant problem with the coolant ventilation line on numerous US-spec B48 engines.

The bulletin identified that the original plastic ventilation line is susceptible to breaking due to high heat, potentially leading to rapid coolant loss.

If not addressed, this could result in complete coolant depletion, risking severe overheating and possible lasting engine damage.

The solution involves replacing the plastic coolant ventilation line with a more durable rubber one, reducing the likelihood of cracks.

BMW categorised this as a “service action” rather than a formal recall.

B48 Variants

This engine comes in 11 distinct variants, offering a diverse range of 17 different torque specifications and 12 unique power outputs.

B48B20 (2020)

  • Power: 54 hp at 4,500-6,500 rpm
  • Torque: 250 Nm (184 lb-ft) at 1,300-4,300 rpm

B48A20U1 (2020)

  • Power: 176 hp at 5,000-5,500 rpm
  • Torque: 280 Nm (207 lb-ft) at 1,350-4,200 rpm

B48B20M0 (2016)

This variant came with two versions with varying torque outputs.

  • Power: 181 hp at 5,000-6,500 rpm
  • Torque: 270 Nm (199 lb-ft) at 1,350-4,600 rpm
  • Power: 181 hp at 5,000-6,500 rpm
  • Torque: 290 Nm (214 lb-ft) at 1,350-4,250 rpm

B48A20M1 (2014)

This variant came in four versions with varying power and torque levels.

  • Power: 189 hp at 5,000-6,500 rpm
  • Torque: 280 Nm (207 lb-ft) at 1,250-4,600 rpm
  • Power: 189 hp at 4,700-6,000 rpm
  • Torque: 280 Nm (207 lb-ft) at 1,250-4,750 rpm
  • Power: 189 hp at 5,000-6,000 rpm
  • Torque: 280 Nm (207 lb-ft) at 1,350-4,600 rpm
  • Power: 261 hp at 5,000-6,000 rpm
  • Torque: 400 Nm (295 lb-ft) at 1,350-4,600 rpm

B48B20M1 (2019)

  • Power: 194 hp at 4,500-6,600 rpm
  • Torque: 320 Nm (236 lb-ft) at 1,450-4,200 rpm

B48B20O1 (2016)

  • Power: 221 hp at 5,000-6,500 rpm
  • Torque: 310 Nm (229 lb-ft) at 1,400-5,000 rpm

B48A20O1 (2015)

This variant came in three versions with varying torque outputs.

  • Power: 228 hp at 5,000-6,000 rpm
  • Torque: 350 Nm (258 lb-ft) at 1,250-4,500 rpm
  • Power: 228 hp at 5,200-6,200 rpm
  • Torque: 300 Nm (221 lb-ft) at 1,250-4,800 rpm
  • Power: 228 hp at 5,000-6,000 rpm
  • Torque: 350 Nm (258 lb-ft) at 1,450-4,500 rpm

B48O1ZIK

  • Power: 241 hp at 4,500-6,500 rpm
  • Torque: 400 Nm (295 lb-ft) at 1,600-4,000 rpm

B48B20O0 (2015)

  • Power: 248 hp at 5,200-6,500 rpm
  • Torque: 350 Nm (258 lb-ft) at 1,450-4,800 rpm

B48B20O1 (2016)

  • Power: 255 hp at 5,000-6,500 rpm
  • Torque: 400 Nm (295 lb-ft) at 1,550-4,400 rpm

B48A20T1 (2019)

  • Power: 302 hp at 5,000-6,250 rpm
  • Torque: 450 Nm (332 lb-ft) at 1,750-4,500 rpm

302 hp Versions

The 302 horsepower versions of the B48 engine feature a reinforced crankshaft with larger main bearings and reengineered pistons that lower the compression ratio to 9.5:1.

These enhancements allow these engines to handle increased boost pressure from a larger turbocharger. The turbocharged air is then channeled through a revamped intake tract.

Unveiled in May 2019, this engine configuration is employed in the forthcoming models of the MINI lineup, including the Countryman JCW, Clubman JCW, and the JCW GP.

BMW B48 2.0i vs 3.0i vs M Variants

The BMW B48 engine, primarily used in the 2.0i and 3.0i models of BMW’s lineup, presents a range of subvariants tailored to different vehicles.

For instance, the G01 X3 xDrive20i and xDrive30i both employ the B48 engine, though in differing subvariants.

In the US, the 20i models predominantly feature the B48B20M0 and B48A20M1 engines, with the latter mainly seen in the MINI Cooper S.

The most common 30i B48 variants in the US are the B48B20O0 and B48B20O1.

Despite their similarities in construction, the 20i and 30i versions of the B48 have distinct differences, primarily in their pistons.

The 20i B48s boast a higher compression ratio of 11.0:1, in contrast to the 30i B48’s 10.2:1.

This difference might seem counterintuitive since higher compression usually equates to more power.

However, the lower compression in the 30i B48 variants facilitates a reduction in mixture temperature and allows for a wider range of ignition timing advance, enhancing power output.

From a tuning perspective, it’s generally more challenging to extract additional power from the 30i B48 variants than the 20i variants, although both are highly receptive to modifications.

The high-performance 302 horsepower B48A20T1 variant, found in M-performance models, incorporates several enhancements to accommodate higher boost pressure and increased stress.

Key upgrades include:

  • a modified crankshaft
  • enlarged main bearings
  • different pistons
  • reduced compression ratio to 9.5:1

These changes allow the B48A20T1 more flexibility under higher boost conditions.

Full List of Cars It’s Used In

  • 2016-2019 120i
  • 2019-present M35i
  • 2016-present 220i / 230i
  • 2019–present 228i Gran Coupé xDrive
  • 2019-present M235i
  • 2016-present 320i / 330i / 330e
  • 2016-present 420i / 430i
  • 2017-present 520i / 530i
  • 2017-present 630i
  • 2016-present X1 20i / 25i / 28i / 30i
  • 2017-present X2 20i / 25i / 28i / 30i / M35i
  • 2018-present X3 20i / 30i / 30e
  • 2018-present Z3 20i / 30i
  • 2019-present Toyota Supra
  • 2019–present Clubman JCW
  • 2019–present Countryman JCW
  • 2020–present MINI John Cooper Works GP
  • 2014–present MINI Cooper S
  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer. He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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