BMW N54 Vs. N55 Vs. B58 Vs. S55: Performance & Reliability

Ever since the twin-turbo N54 hit the market in the 2007 BMW 335i, BMW has been building on the design of the turbocharged, direct-injected inline 6 engine. In 2010, the 335i received the updated N55 engine followed by the B58 in 2016, however, the model was rebranded to the 340i. Unsurprisingly, the success of the turbocharged inline 6 led to its introduction in the F80 BMW M3 beginning in the 2015 model year.

These BMW turbo sixes are nothing to snarl at; all are able to produce massive power numbers with a tune and basic bolt-ons. Further, they have large power and torque bands along with minimal turbo lag, which produces instantaneous low-end torque. How do the BMW N54 vs N55 vs B58 vs S55 stack up against each other?

BMW N54

Since the initial release of the BMW N54, the engine has gained quite a positive reputation in the tuning community. Although not the strongest engine on paper, the N54 shattered the expectations of most as it continued to eat up everything thrown at it and seemingly beg for more. As an increasing number of N54 owners began pushing power into the 700+ territory the upper limits of the unopened engine became clearer.

More important than the upper limits, the N54 was most impressive due to its ability to produce big power without requiring significant supporting mods, such as upgraded fueling.

BMW N54 Specs

Stock Power: 300 HPWorld Record HP: ~1,005WHPDisplacement: 2979cc (2.979L)Turbocharger: Twin turboCompression: 10.2 to 1Bore x Stroke: 84.0mm (3.31”) x 89.6mm (3.53”)Internals: Forged crank and rods. Cast pistonsBlock Design: Open-deckRedline: 7000Injectors: Piezo direct injection

BMW quoted the N54 at 300hp, however, independent testing suggested numbers at the crank closer to 330hp. Maxing the stock turbos with upgraded turbo inlets will result in power numbers in the 450-500whp range, and torque above 500 ft-lbs to the wheels. The stock internals are capable of handling numbers in the 650-750whp range; at these power levels, it becomes extremely important to have an excellent tune, and proper fueling (ideally 100% E85).

Open-deck blocks and cast pistons are not great at handling extreme boost pressures for long periods of time. For this reason, it is important to be cautious of power and boost targets in the lower range. The pistons are traveling slower at lower RPMs, which results in the high boost pressure sitting in the cylinder for a longer period of time.

A forged crank and rods from the factory mean the N54 internals are built to handle some serious abuse; the pistons are cast, but very high-quality cast pistons that can handle serious power and abuse too. Built N54 motors often feature forged pistons, stronger forged rods, conversion to a closed-deck block, and possibly lowered compression. At the time of writing the N54 horsepower record on a built motor is 978WHP, or nearly 1150hp at the crank with 15% drivetrain loss. Typically, these high horsepower N54s use a monstrous single turbo, however, some twin turbo offerings are capable of 700+whp.

BMW N54 Reliability

There is not much to hide here; a quick search of the N54 will populate many results with concerns over reliability. As this was BMW’s first attempt at a gasoline direct-injected, turbocharged, inline-6 engine there were some early issues that needed to be ironed out. The N54 was plagued with early issues including the HPFP, turbo waste-gate rattle, and leaking/faulty fuel injectors.

Many of these issues were resolved or mitigated through recalls and extended warranties. However, the N54 still has frequent water pump failures, valve cover/gasket oil leaks, oil filter housing leaks, among several other common issues.

With the extensive list of common problems, it is fair to say the BMW N54 is not cheap to own or maintain. We do believe it is better than some suggest, however, if you take the car to the shop for every minor issue and do not DIY any repair jobs the bills can certainly add up quickly.

Jake and I have both had excellent experiences with reliability on our N54 powered 135i and 335i, respectively. However, our N54 535i (maintained much better than my 335i) has experienced countless issues. Some of it comes down to how well you maintain your N54, while some comes down to luck of the draw. Nonetheless, you must pay to play and the N54 is no exception.

Overall Thoughts on the BMW N54

Reliability Rank: 4

Tuneability Rank: 1

Value Rank: 1

**Ranks are as compared between the four turbo, inline 6 engines**

1 = Best

4 = Worst

In the BMW N54 vs N55 vs B58 vs S55 fight, the N54 earns the worst score for reliability. Fortunately, BMW learned its lesson on the N54 and focused on improving the reliability of its future turbo engines. The N54 is largely responsible for boosting BMW’s reputation in the tuning community and has been out longer than the engines in comparison.

Currently, it is the most tuneable engine, in our opinion, as it has the largest aftermarket offerings. Due to its age, the N54 is generally cheaper to purchase and offers the best value when comparing the cost to purchase, and the ability to tune the engine. However, the initial value of purchasing the N54 may diminish due to potential reliability issues.

BMW N55

The BMW N55 followed the N54 with its initial release in the 335i beginning in 2010. Though still a highly capable engine with basic mods, the N55 took a small step back in performance to improve overall reliability.

Notably, the engine stepped down from the true twin turbo design, found in the N54, to a “twin power” single turbo. The single turbo in the N55 is a larger turbocharger that produces the same power as the N54, stock for stock. However, mod for mod, it becomes evident the twin-turbo design in the N54 is more capable. Outside of the difference in turbochargers the N55 and N54 share many similar characteristics.

If you are interested in learning about the BMW N55 engine in more detail, take a look at out Ultimate BMW N55 Engine Guide.

BMW N55 Specs

Stock Power: 300 HPWorld Record HP: ~750WHPDisplacement: 2979cc (2.979L)Turbocharger: “TwinPower” Single TurboCompression: 10.2 to 1Bore x Stroke: 84.0mm (3.31”) x 89.6mm (3.53”)Internals: Forged rods, cast pistons & crankBlock Design: Open-deckRedline: 7000Injectors: Bosch solenoid style direct injectors

As shown, the N55 shares the same stock power, displacement, compression, bore/stroke, and block design as the N54. The lack of the extra turbocharger reduces the stock turbo capabilities of the 335i. Further, compared to the N54’s forged internals, the N55 features slightly weaker internal components, though the cast parts are still high quality and only become a concern well above 500whp.

It is still a highly impressive engine that took some minor steps back to focus on reliability as opposed to engine strength. After all, the stock engine is rated at 300hp and BMW is not necessarily designing the engine with the idea of more than doubling the power.

BMW N55 Reliability

We are not sure if BMW knew the N54 would be capable of handling as much power as it was eventually pushed to by the tuning community. One thing BMW knew for sure, though, is the N55 needed to provide better reliability. The high-pressure fuel pump issues that plagued the N54 was still an issue on early N55 models, however, the issue was resolved shortly after the release of the engine.

Injectors were changed from the piezo style to solenoid style as the piezos had too many issues on the N54, were too expensive, and did not live up to expectations. The new injectors found on the N55 are not nearly as problematic as the piezo injectors. Lastly, issues with waste-gate rattle were mostly resolved on the N55.

Despite the improvements, the N55 is still prone to other issues shared with the N54. These include common problems with the water pump, valve cover and gasket, and oil filter housing and gasket. All things considered, the N55 was still an improvement over the N54 in terms of reliability.

Overall Thoughts on the BMW N55

Reliability Rank: 3

Tuneability Rank: 4

Value Rank: 2

Though the N55 does not earn the highest marks for reliability, it is not to suggest the N55 is a terribly unreliable car. It is more of a testament to just how good the two remaining engines are. When comparing the N54 vs N55 vs B58 vs S55, the N55 comes in third in terms of reliability. BMW’s B58 and S55 engines are newer, so more issues may pop up down the road.

Compared to the two former engines the N55 has been on the road longer, allowing for additional time for tuning developments. There are more tuning options available, however, the N55 single turbo design limits its tuneability as compared to the twin-turbo S55. Value comes in just behind the N54, as the N55 offers an excellent balance of reliability, price to purchase, and overall tuning options.

BMW S55

Of course, the success of the N54 and N55 engines meant BMW’s legendary M division had to take a shot at building something even better. Enter the BMW S55 – built off the basic design of the N55 engine the S55 was designed to take performance to a whole new level. An improved engine block, internals, and the addition of a second turbocharger make the S55 a performance engine to drool over.

Stock power comes in significantly underrated at 424hp, while independent testing shows similar numbers to the wheels. In our opinion, BMW nailed the design and specs of the S55, and it is truly the most capable engine in this comparison, by a long shot.

BMW S55 Specs

Stock Power: 424 HPWorld Record HP: 1150WHP (~1350 crank horsepower!)Displacement: 2979cc (2.979L)Turbocharger: Twin turboCompression: 10.2 to 1Bore x Stroke: 84.0mm (3.31”) x 89.6mm (3.53”)Internals: Forged crank and rods. Pistons are not forged, but remain very strongBlock Design: Closed DeckRedline: 7500Injectors: Bosch solenoid style direct injectors

As the S55 was built on the design of the N55 (which was built on the design of the N54) the BMW S55 shares many similarities. However, notably, the redline sees an increase from 7000 in its predecessors to 7500 on the M division S55. Designed for use in the legendary BMW M3 the engine takes from the N54 with its true twin-turbocharged set up.

Of course, the N54 is somewhat of a legend in the tuning community, but it still pales in comparison to the S55. Just about every part of the S55 is bigger, better, and stronger than the N54. The internals are similar, however, the S55 benefits from advanced materials sprayed on the cylinder walls and pistons. Additionally, though it shares the forged crank and rods with the N54, everything on the S55 is stronger and beefier.

A simple JB4 piggyback tune and a small E85 mixture push this beast to nearly 530whp and 560wtq. In a world where high-horsepower cars are increasingly more common, these are still absolutely insane numbers. Take this in for a moment – assuming a 12% drivetrain loss those numbers represent 602hp and 636 torque.

Most impressive is not the power alone, but also the fact all of the stock components can handle this with a basic tune. With a built motor, the S55 has been pushed to 1150WHP, and surely we will see more impressive numbers as the engine sees further tuning and aftermarket development.

BMW S55 Reliability

The BMW S55 has proven to be an exceptionally reliable engine over the course of its 9-year lifespan. The vast majority of S55 engine problems, with the exception of a couple, are relatively minor in the grand scheme of things. Most of the S55’s problems revolve around cracking plastic, i.e. the charge pipes and valve cover, and worn gaskets, like the valve cover gasket and oil filter housing gasket.

Crank hub issues are a more substantial problem that seems to also affect a small number of S55 engines. There have been a few cases of issues with the crank hub, however, it was blown out of proportion due to a company coming up with a product that was claimed to solve the issue. In reality, it was worse than the factory part. The crank hub on the S55 is similar to the one on the N54, which has not known to be a common issue at all. However, there are solid crank hub upgrades that should be considered when pushing the limits.

The main coolant pump on the S55 is belt driven, which holds up much better than the electric water pump found in the N54 and N55 engines. Valve cover and oil filter housing leaks are common on a lot of BMWs and the same can be said for the S55. BMW’s S55 engine is without any serious “common” issues even when modified, so this engine earns high marks for reliability.

Overall Thoughts on the S55 Engine

Reliability Rank: 2

Tuneability Rank: 2

Value Rank: 3

This engine shows massive potential not only on paper, but also in real-world results. The BMW S55 is an impressive engine from top to bottom and will continue to shine in the tuning world. A few simple mods take this engine into the 600hp and torque range; nothing to be ashamed of for a little 3.0L inline-6.

The BMW S55 ranks number 2 in reliability, mostly due to the fact that it doesn’t have quite the same amount of aftermarket support as the N54. Despite not having quite the catalog of the older BMW twin-turbo inline-6, anything that you could possibly want in order to make big power from the BMW S55 is available at this point. Coupled with the S55’s robust architecture, a very strong case could be made that the S55 has one of the best aftermarket scenes in the modern BMW space.

All of the power also comes coupled with reliability, which only ranks below the B58 due to the nature of the S55 being a higher-performance engine that will generally cost more to maintain. Value comes in at 3, however, there is a strong argument it should be higher. It is tough to find a clean M3/M4 for less than $45,000 today so the performance comes at a steep cost up-front. Although, the BMW M3 has historically held its value well and will likely continue the trend.

BMW B58

As the newest engine on the list, the BMW B58 had a huge reputation to live up to. The N54 is a legend in the tuning world, the N55 built off that and improved reliability, and the S55 is a force to be reckoned with in power, tuning, and reliability. Did BMW live up to that reputation? Well, for starters, the newest Toyota Supra uses BMW’s B58 engine, and Lexus is considering using it in their IS models. Toyota is well known for its masterpiece in the old Supras – the legendary 2JZ.

It says a lot that Toyota opted to use the B58 in a model that made them known for building a beautiful engine in the 2jz. Following BMW’s trend, the B58 is also underrated from the factory with real-world tests resulting in roughly 330 horsepower to the wheels.

BMW B58 Specs

Stock Power: ~330hpWorld Record HP: ~900WHPDisplacement: 2998cc (2.998L)Turbocharger: Single “Twin Power” TurboCompression: 11.0 to 1Bore x Stroke: 82.0mm x 94.6mm (3.23in x 3.72in)Internals: Forged crank and rods. Cast pistons.Block Design: Closed DeckRedline: 7000

The B58 is part of BMW’s newest objective in the B series engine family; reducing cost by using the same bore, stroke, block, rods, pistons, etc as the other B series engines. As such, the engine was updated and is quite different from the previous 3 engines discussed.

Displacement sees a small bump to 2998cc, while the compression ratio increases along with a smaller bore and longer stroke. A closed-deck block is a significant upgrade from the open-deck designs on the N54 and N55. Additionally, it receives the forged crank and rods as with the N54. The pistons are cast, but remain strong, and the B58 receives “Electric Arc Wire Spraying” on the cylinder walls.

Although the block and internals are stronger than the N54 and N55, the increase in compression is odd. Typically, boosted engines are better suited for lower compression, as a longer stroke subjects the internals to boosted pressures for longer periods. With that being said, the B58 is still capable or around 650 horsepower and 600wtq with stock internals. At that point, the rods and bearings start to enter the danger zone. To learn more, take a look at our How Much Power Can the BMW B58 Handle Article.

On paper, the B58 matches, if not slightly exceeds, the N54 for strength and durability. Although, the single turbo will likely limit its capabilities without upgraded turbo(s). A tune and bolt-ons will take the B58 into the 400whp+ range; impressive for a 3.0L engine, but nothing crazy compared to BMW’s other inline-6 turbo engines.

BMW B58 Reliability

In quite a few enthusiasts’ opinions, the BMW B58 is one of the most reliable turbocharged engines that BMW has ever made. Unlike the BMW N54 and N55 engines on which it was based, BMW has resolved almost all of the high-ticket repair items that were common problems previously. For example, there aren’t endless cases of waste-gate rattle, HPFP failures, or fuel injector failures on the B58.

While most of the major issues have been resolved at this point, the B58 still experiences many of the same basic wear and tear issues that we have all come to know and expect from turbocharged BMW engines at this point. Failing VANOS solenoids, leaking valve cover gaskets, and PCV valve problems are all still par for the course. Fortunately, there is not much more to discuss with regard to BMW B58 reliability.

Overall Thoughts on the BMW B58

Reliability Rank: 1

Tuneability Rank: 3

Value Rank: 4

When we initially wrote this article in 2019, we were optimistic and excited to see the true potential of the BMW B58 realized. Well, here we are 4 years later and the BMW B58 is still considered one of BMW’s most reliable, modifiable, and versatile turbocharged engines. Overall, our opinion of it hasn’t changed since then, we’ve just been lucky enough to see the aftermarket space do some incredible things with both B58-powered BMWs and with the MkV Supra.

In the years to come, the B58 will be an excellent performance value, and in some cases it already is. B58-powered F3X cars are nearing the bottom of their depreciation curve, making them fantastic value for money. With that being said, so are F8X M3/M4s. An S55-powered M3 can be found for roughly $10,000 more than a B58 car. The B58 is a great engine, but the S55 is better. Much better when you consider you get the full package in the M3. For that reason, the B58 scores the worst value rating.

The B58 is an incredible tuner/mod-friendly engine. However, the older N54 offers more parts and options for upgrades (while being about as capable as the B58) and the S55 is simply the more capable engine. Reliability scores the highest marks compared to the N54, N55, and S55.

Final Thoughts on the BMW N54 vs N55 vs S55 vs B58

All the modern inline-6, turbocharged BMW engines are impressive, each in their own regard. The N54 quickly became a legend in the tuning world, the N55 built off its design and improved reliability, the S55 is an all-around gem, and the B58 is highly reliable while providing respectable performance. Of course, we are biased towards BMWs here at BMWtuning.co, but we fell in love with these modern turbo BMW engines for a reason. Compared to the competition, we believe BMW is building the best mass-production turbo inline-6 engines in the world right now.

Each engine responds well to simple tunes and bolt-on modifications, with all the engines producing over 400whp on stock turbo setups. Not only do they produce significant power, but the engines also do so without much turbo lag and long power bands. Additionally, BMW built on a great engine design in the BMW N54 and continued to improve the reliability of the succeeding engines. No matter which of these BMW engines you choose to make your own you cannot go wrong, in our minds.

Which of these BMW turbo inline-6 engines is your favorite?