BMW N20 vs B48: Performance & Reliability

The BMW N20 and B48 have big reputations to live up to. They power 20i, 25i, 28i, and 30i models; a large percentage of all BMW models. Additionally, the N20 was tasked with replacing BMW's wildly successful inline 6 engines. These small 2.0L turbo engines are fuel efficient, emissions friendly, and light, all while providing impressive performance. How do the BMW N20 and B48 engines stack up?

BMW N20 Engine

Introduced in 2011, the N20 began phasing out the N52 the following year. It was a big deal. BMW is long known for their ability to build beautiful inline 6 engines. The N20 marks a big change to the inline 4, turbo engine. Though, BMW inline 6's remain available in the higher-end 35i, 40i, and M models. Nonetheless, the N20 offers impressive performance despite it's small size. The most powerful version, found in 28i models, makes 241hp and 258tq. Not too bad for a 2.0L engine. Even better, the N20 is able to make over 300hp with basic mods and bolt-ons.

BMW N20 EnginePin

BMW N20 Specs

Stock Power: 241hp

World Record HP: Estimated 400WHP

Displacement: 1997cc (1.997L)

Turbocharger: “TwinPower” Single Turbo

Compression: 10.3 to 1

Bore x Stroke: 84.0mm (3.31”) x 90.1mm (3.55”)

Internals: Cast iron internals

Block Design: Open-deck

Redline: 7000

Injectors: Bosch solenoid style direct injectors

***Specs for 2.0L BMW N20 engine (N13 and N26 have slightly different specs)

BMW N20 Performance & Mods

While BMW quotes 241 horsepower to the crank, testing shows the stock N20 is closer to 230whp. Assuming a standard 15% drive-train loss the N20 is closer to 270 horsepower. Already a solid improvement over the 3.0L naturally aspirated N52 engine. Of course, turbo BMW engines gain respectable power from simple mods. A tune and bolt-ons push the N20 to 300+whp. However, don't let engines like the N54, N55, or B58 fool you. Unfortunately, the N20 isn't as stout. It is likely best to keep boost around 22psi peak.

We've seen dynos showing nearly 400whp. Though, this is on built N20's with a larger turbo. Not too many N20 owners are truly pushing the limits. For most, it probably makes sense to upgrade to the turbo inline 6 engines if you're looking for 330+whp. This is not meant to be a knock towards the N20's performance. It's truly an excellent engine for its size. However, the N20 has it's limits and they should be respected.

Read our post about N20 mods here: BMW N20 350hp

BMW N20 Reliability

Overall, expect the BMW N20 to be a reliable engine. It seems to be a slight improvement over the preceding N52 engine. A concerning common problem is the N20 timing chain. This mostly applies to N20's produced prior to 2015. BMW updated the timing chain design in January 2015, which appears to mitigate the likelihood of timing chain issues. Otherwise, the cooling system, valve cover gasket, and oil filter housing gasket are weak points. The N20 is not alone as many BMW's are plagued by those issues.

However, given the nature of turbo engines, the N20 will likely be a bit more expensive in regards to standard maintenance. Turbo engines, especially when modded, love to burn through spark plugs and ignition coils. Not too expensive, but they can add up over time. Additionally, more frequent oil changes are always a good idea. We recommend changing the oil every 5,000-7,000 miles.

Read our post about N20 reliability here: Common BMW N20 Problems

BMW B48 Engine

Following the N20, BMW's B48 packs a solid punch for a 2.0L inline 4. Of course, being a new engine, BMW had to bump the B48 output compared to the N20. Peak power comes in at 248-255hp on 30i models. However, BMW also went a step further with the B48. An upgraded version producing 302hp is found in new 35i models. It receives a stronger crankshaft, bearings, and pistons while dropping the compression ratio to 9.5:1. Additionally, responsible for delivering the impressive power, the upgraded 302hp B48 receives a larger turbo.

Another note, the B48 is a part of BMW's modular B series engine objective. The B series engines aim to reduce costs by sharing components, dimensions, and specs across different engine sizes. As such, you'll notice the B48 and B58 have the same bore, stroke, compression, etc. Some may shame BMW for cutting costs. However, we believe it is a step in the right direction. We believe it allows BMW to focus on perfecting one design.

BMW B48 EnginePin

BMW B48 Specs

Stock Power: 248hp-255hp

World Record HP: Estimated 300WHP

Displacement: 1998cc (1.997L)

Turbocharger: “TwinPower” Single Turbo

Compression: 11.0 to 1

Bore x Stroke: 82.0mm (3.23”) x 94.6mm (3.72”)

Internals: Unknown

Block Design: Closed-deck

Redline: 7000

Injectors: Bosch solenoid style direct injectors

***Numbers based on B48 30i engine

BMW B48 Performance & Mods

As with the N20, the B48 comes slightly underrated from the factory. Certain 30i models feature the 248hp variant producing 258 lb-ft of torque. Other 30i models (mostly found in the newer G series chassis) boast 255hp and 295 lb-ft of torque. Aftermarket testing shows numbers closer to 230-240whp. Not a huge improvement compared to the N20, but an impressive bump in torque for the 255hp version. Not many have pushed the B48 too hard, yet. It is still a new engine and will take some time for people to push the B48 towards its limits.

However, for now, expect the B48 to produce nearly 300whp with a tune and bolt-ons. Again, pretty similar to the N20. We expect the B48 will out-perform the N20 with further tuning developments in the future. However, engine strength is the big question. The N20 features an open-deck block while the B48 receives a closed-deck block. Definitely a sound improvement for the B48. Though the bump in compression to 11 to 1 is questionable. Generally, higher compression is not great for boosted engines. Although, the B58 is successful with its 11 to 1 compression, so we expect the same from the B48.

Read our post about B48 mods here: BMW B48 300whp

BMW B48 Reliability

This is a tough one. The great news is - the B48 is off to an excellent start from a reliability perspective. However, it's really too new to tell what may pop up down the road. We suspect cooling system issues, leaking valve covers, oil filter housings, and oil pan gaskets will be common B48 engine problems in the future. These are pretty common issues among almost all BMW's.

For now, the B48 seems to be free of any common problems. Time will tell what may arise in the future. Nonetheless, expect the B48 to be a reliable engine overall. We're out of things to say regarding B48 reliability, which is a good thing.

*We'll write a B48 common problems post in the future.

BMW N20 vs B48 Performance

Both the N20 and B48 pack small 2.0L turbo engines that produce impressive power for their size. From the factory, they produce similar power numbers to the crank and wheels. However, B48 powered 35i models see a serious upgrade. Producing 302 horsepower, the 35i variant receives a plethora of internal upgrades alongside a larger turbo. Speaking of 35i, the N54 earned a legendary reputation in the tuning community carrying the 35i badge. These B48's have a lot to live up to.

Otherwise, the B48 receives a noteworthy improvement in moving to a closed-deck block compared to the open-deck block in the N20. However, compression also increases on the B48 which isn't the greatest for strength on boosted engines. It's working for the B58, though. The N20 never earned a great reputation for strength. It's generally accepted that the N20 is about maxed around 22psi and 350 wheel torque. The limits of the B48 are still rather unknown. Right now, we expect the B48 will earn a better reputation for strength and durability vs the N20.

BMW N20 vs B48 Reliability

Expect both the N20 and B48 to be reliable engines. The N20 does have a well known problem in the timing chain. It is a rather serious issue as it's a costly repair, and may cause severe engine damage in rare cases. Otherwise, the N20 is plagued by typical BMW issues. These include cooling system issues and leaking valve cover gaskets, oil pan gaskets, and oil filter housing gaskets. Though, these issues usually don't pop up until 80,000 - 100,000+ miles.

So far, the B48 appears the more reliable engine. The B48 is without any serious common problems to date. Although, we expect the B48 will eventually suffer similar common problems as the N20, less the timing chain. That is not to say either engine is unreliable. Gasket oil leaks can be expensive repairs at the shop. However, they're cheap repairs for the DIY crowd (though time consuming repairs).

BMW N20 vs B48 Final Thoughts

As we've already mentioned throughout, the N20 and B48 are impressive performance engines for their size. Both can make over 300whp with tunes and basic bolt-ons. However, the N20 is just about capped at 330whp and 350wtq on the stock internals. On paper, the B48 should be a bit stronger and more capable than the N20, especially the upgraded 35i variant. Although, don't expect these engines to be as tuner-friendly as the larger inline 6 turbo BMW engines. Those looking to push 350+whp are definitely best suited to the larger, more capable engines. That is not at all a knock to the N20 or B48, but it is reality.

Otherwise, the N20 and B48 are both relatively reliable engines. Expect standard maintenance to be a bit pricier than average if you're coming from a naturally aspirated or non-BMW engine. Especially tuned and modded N20 or B48 engines. Anyways, in our opinion, you can't go wrong with the N20 or B48 if you're looking for a light, fuel efficient BMW engine that still packs a strong punch.

What are your thoughts and experiences with the N20 and/or B48? Leave a comment and let us know!

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13 thoughts shared

  1. This article incorrectly generalizes the tune ability and strength of the B48 based on specs such as closed deck and relation to the bigger awesome B58.

    In realty, B48 powered vehicles like the F30 are slower than their N20 counter parts (see CR and C&D test results with similar spec’s cars) tuners have not been able to extract as much power out of the B48 either by PTF and Dinan:

    N20 Dinan Dyno: 268 hp
    B48 Dinan Dyno: 254 hp

    N20 BMS Dyno: 233.7 hp
    B48 BMS Dyno: 230.68 hp

    BM3 on N20
    N20 (low-compression 28i)
    Stage 1 91 octane: 16%HP / 20%TQ
    Stage 1 93 octane: 18%HP / 22%TQ
    Stage 2 91 octane: 20%HP / 24%TQ
    Stage 2 93 octane: 22%HP / 25%TQ
    Stage 1 E30 octane: 21%HP / 24%TQ
    Stage 2 E30 octane: 25%HP / 27%TQ

    BM3 on B48
    Stage 1 91 octane: up to 14% HP / 26% TQ
    Stage 1 93 octane: up to 16% HP / 26% TQ
    Stage 1 E30 octane: up to 20% HP / 28% TQ
    Stage 2 91 octane: up to 16% HP / 28% TQ
    Stage 2 93 octane: up to 18% HP / 28% TQ
    Stage 2 E30 octane: up to 22% HP / 30% TQ

    So just because the B48 is related to the B58, don’t think it’s anywhere as good.

    1. Hello,

      Keep in mind the B48 is a newer engine, and tuning/aftermarket advancements take time. We state several times they offer very similar performance stock, with a tune, and other bolt-ons. The reference to the B58 is in regards to engine strength with their closed deck blocks. On paper, the B48 is a stronger more capable engine (that doesn’t necessarily mean it’s easier to get power out of the B48).

      Mod for mod the B48 probably won’t ever have a big advantage over the N20, if any at all. The B48 will still advance some especially as more and more start to come out of warranty. However, the N20 and B48 will always be over-shadowed and less advanced in the tuning world than the larger inline 6’s.

      Best Regards,
      BMW Tuning

  2. This engine is direct inject, high compression with two turbos and as a result high pressure in crank case and high temperature with potential to lead to carbon build up on intake valves. Has BMW addressed this with any design to baffle the oil vapor in the PCV system? This engine is in my Mini Cooper S. The one common theme I am hearing is change the oil at 3000 to 5000 miles. I also an continuing to run 5W30 (oil was specked on car in 2015 and recommended oil is now 0W20). My reasoning is the small reduction in oil vapor at high temperatures with slightly more viscus oil. Nowack (SAE SN) test a bit lower with higher viscosity oil.

    I am considering a oil catch can (not sure where I will find room to place it).

    Comments please. Thank you.

    1. Comment author image

      Jonathan Outterbridge

      says:

      It’s a single turbo. If your PCV system doesn’t work then yes you can add a catch can. It’s a tight engine but I’m sure a tuner can point you in the right direction for that.

    2. Comment author image

      Chadwick Strothman

      says:

      I’m putting one in one the left behind the bumper under the headlight. similar to the windshield fluid reservoir on the right. The lines might be long and it’ll be a wait and see for codes. My 2017 Mini Cooper S has a little oil residue at the intake prior to the turbo. 16K miles. This and a good wastegate are what I’m keeping an eye on.

  3. What i”ve seen is that the B48 is having issues with piston failure. Most of the time it is piston nr.2
    I would say on the 11:0 compression version 300hp is about the max on stock internals. 320hp on the 10.2:1 (B48a20b).
    These engine’s perform great and have very good fuel economy. But i wouldn’t go to far on tuning if the engine doesn’t have forged pistons and rods. Currently 83k miles on a 300hp B48. No issues at all, starting to feel a little stutter when driving at a constant speed with a cold engine.. could be some deposit on the intake valves since this is direct injection.
    Oil changes are important on these if you want max reliability. ( 5000 – 8000 miles ) definitly on a tuned B48

    1. Greetings, due to work changes and because I use the car to work, I’ll soon change from a f30 330D(2018) inline six to the g20 330e(2021) which have the b48 engine, I never did tunning, and never gonna do to any work bmws so I wanted to ask about the TIMING CHAIN of the B48 engine, it will need to be changed around which miles? Somebody knows?
      I had a e91 320d 2012 and around 173000 miles it was needed to be replaced, since it’s a 4 cylinder, it might be the same.

      Cheers

      1. To do timing chain on the B48 the transmission will need to come off. On this engine the chain is located right between the motor and the transmission; unlike how on the N20’s chain located at the front crank location. Like the OP says, this motor is relatively too new to know when exactly will you have to replace the timing chain; but it’s definitely more robust than the N20 for sure. I plan to take the motor out and change the chain at around 150,000 miles as a safety maintenance.