BMW S55 vs S58: Performance, Reliability & Tuning

BMW forever left the world of naturally-aspirated performance motors in M-series cars in 2013 with the launch of the S55. Succeeding the NA V8 S65 motor, the S55 was a 3.0L twin-turbocharged inline-6. Despite being the performance version of the N55, the S55 has little in common: a closed deck block, twin turbos, forged pistons, lightweight crankshaft, and dual high pressure fuel pumps, to name a few.

While the official release won't be until Q4 2020, it's no secret that the S58 is the next-in-line motor for the M3 and M4 vehicles. However, the S58 has already hit the streets in 2020 model year X3M and X4M models. Based off of the B58TU engine, the S58 remains very similar in displacement to the S55 with a 3.0L twin-turbocharged inline-6 engine. 

While the rumored looks of the G80 M3 are god awful (we hope BMW reads this), the S58 engine has much more in store. With that being said, how will the S58 stack up against the S55 in terms of performance, reliability, and tuning potential?

BMW S55 Engine

BMW S55 EnginePin

BMW S55 Engine Specs

Stock Power: 425hp / 406tq (different versions have anywhere from 405hp-493hp)
World Record HP: 1,150whp (approx. 1,350 crank hp)
Displacement: 2,979cc (2.979L)
Turbocharger: Twin "single-scroll" turbos
Compression: 10.2 to 1
Bore x Stroke: 84.0mm (~3.31”) x 89.6mm (~3.53”)
Internals: forged steel crankshaft, forged aluminum alloy pistons and rings
Block Design: Closed-deck
Redline: 7,500 rpm
Injectors: Bosch solenoid style direct injectors

S55 Engine Performance & Mods

Some people were disappointed that BMW moved away from the V8 platform. However, there certainly is no disappointment in S55 performance capabilities. While the N55 was toned down for reliability, the S55 was cranked up to a whole new level. 

With 425hp out of the gate, this engine is believed to be significantly underrated with stock dyno's coming in around the same numbers. With basic FBO mods such as a tune, downpipes, intake, intercooler, and E85 gas, the S55 engine can push a cool 600whp. And better yet, this list of FBO mods won't run you any more than $2,000. Talk about serious power! 

With a horsepower record of 1,150hp to the wheels, the S55 is the highest horsepower BMW engine to exist. With partially forged internals, a closed-deck, and special cylinder wall and piston coating, the S55 engine is the most capable and powerful BMW engine in existence. But, what about the next generation S58?

Read our more detailed tuning guide here: How to Build a 600WHP BMW S55 M3/M4 for $2,000

S55 Engine Reliability

After 6-years of on the road data, the S55 appears to be an extremely reliable motor. On pre-2016 engine models, the crank hub was complained to be a high-failure point, resulting in a "spun" crank hub. The crank hub issue turned out to be blown out of proportion by a company called TPG tuning, using a scare tactic to sell more of their aftermarket crank hubs. The S55 crank hub is the same design as used on the N54 and N55, and while it can and has failed on stock S55's, it is a highly isolated problem which was improved by BMW in 2016. 

Outside of this over blown issue, the S55 appears to be a bulletproof engine. There are a handful of small issues, common across all BMW's, such as HPFP failure, carbon build-up, etc. but overall, nothing that should be a serious red flag for any potential buyers. 

The combination of power to reliability on the S55 is astounding and unrivaled by any other BMW engine.

BMW S58 Engine

BMW S58 EnginePin

BMW S58 Engine Specs

Stock Power: 473hp / 503hp and 442tq (503hp is for Competition models)
World Record HP: TBD - too early to know
Displacement: 2,993cc (2.993L)
Turbocharger: Twin "single-scroll" turbos
Compression: 9.3 to 1
Bore x Stroke: 84.0mm (~3.31”) x 90.0mm (~3.54”)
Internals: forged steel crankshaft, forged pistons and rods
Block Design: Closed-deck
Redline: 7,500 rpm
Injectors: Bosch solenoid style direct injectors

S58 Engine Performance & Mods

Given that the S58's have just hit the streets, there aren't any performance mods out there yet. Additionally, the tuning capabilities are unknown and will continue to be until some of the big tuning companies are able to get their hands on these vehicles and start building products. 

With that being said, we can still speculate. Off the bat, the standard S58 puts down 473hp amd 442tq, that's an increase of 48hp and 36tq over the standard S55. The Competition models will push that even further, with an additional 78hp over the standard S55 and still 10hp over the beefed up S55 in the M4 GTS. 

Additionally, the S58 is built off of the B58, which has been extremely impressive since its debut in 2015. Many individuals think the B58 used in the Toyota Supra will be a good preview of what to expect with the S58. The B58 featured in the Supra is essentially a more highly-tuned BMW engine. While the Supra is still extremely new, we've already seen one hit 770HP at the crank, and one of the most notable Supra tuners believes the internals on the B58 are good for 1,000whp+.

S58 Engine Reliability

Again, since the S58's have barely hit the road so far, we can't really provide any definitive opinions on this. The S55 significantly enhanced its reliability over just about every previous M-series engine. And the B58 has been a very reliable and capable engine to-date.

With that being said, BMW reliability seems to be trending in the proper direction and we're hoping that this trend will continue into the S58 engine. However, as power increases and additional technology is added, the risk for more common problems increases. As always, you can likely expect a few issues with the common BMW problem childs including the HPFP, oil filter housing, valve cover gasket, water pumps, etc.

We'll update this post with an update on S58 reliability once we have some data to go off. 

BMW S55 vs S58 Performance

What is clear as of right now, is that S58 is more powerful and offers better performance, from the factory. What isn't clear is, which platform has the greatest potential?

However, if you took an S55 and S58 today, we would deem the S55 to be more capable in its current form due to the lack of performance modifications available for the S58. With that being said, based on the performance numbers we've seen from the B58 so far, we think the S58 will eclipse the S55 in power output and performance potential once the engine has been on the market long enough for products to being being released.  

We have high hopes and expectations for the S58, and believe it will be as rock solid as the S55 given they are using virtually the same engine internals.

BMW S55 vs S58 Reliability

The S55 is a masterpiece when it comes to reliability for an M-series vehicle. The B58 is still somewhat new to have developed a bunch of "common problems", but from what we can tell so far, the B58 is a highly reliable motor. Using that as a proxy for the S58, we hope this engine will live up to and potentially even surpass the reliability found in the S55 engine. 

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6 thoughts shared

  1. Dunno where you got the “record” number of ~1300hp, but there are plenty of S54 and S38 builds above that.. There’s an S85 with 1850hp crank

    1. There are a couple S55’s making about 1100-1200whp. Some single turbo setups and also a Kratos twin turbo setup; may be more now days but haven’t really kept up with records lately. Anyways, not quite sure why the S38, S54, or S85 are relevant here. The S85 might be the most realistic comparison in that it’s an aluminum block, but it’s also a 5.0 V10 so still a far cry.

      As for the S38/54 – they’re great engines but iron blocks are dead. While incredibly strong they don’t really have a place in the modern automotive world. The HP records are simply for fun. In reality, any engine can be built to handle serious power and boost with the right knowledge/builders and a deep wallet.

      Best Regards,
      Zach

  2. S55 is a reliable engine? Is that a joke? And no it was not fixed in 2016, or even acknowledged by bmw. What is your source for this? If you did your reseach, you’d know its simply not true. Amongst the crank hub issue, the s55 also has issues on reliability of the intercooler, as well as accelerated wear of the rod bearings. Bmw has lost alot of customers to AMG due to this engine

    1. Hi Taso,

      The intercooler is known to develop some problems, which appears to be becoming a bit more common as time goes by. Rod bearing issues are really not that common on the S55. Sure, they can happen and there are some cases. The ultimate cause would come down to lack of oil flow as it’s the exact same bearing design as used on the N54.

      Bearing issues occasionally happen on the N54 but there are plenty out there running 150,000+ miles on heavily modded engines with no bearing issues. Even some that have been replaced at that mileage and look nearly brand new. The S55 doesn’t appear to have any oil flow issues that would cause the bearings to fail. As such, most problems are likely isolated cases or due to poor maintenance, OCI’s that are too long, etc.

      Regards,
      BMW Tuning

    1. Comment author image

      Manny Gonzales

      says:

      It wasn’t really addressed but more like fixed. If you calculate the amount of people who have reported problems to the amount people have bought them, the amount of people who have crankhub problems drops significantly after 2016. The crankhub problem is used by so many timers to make you buy it and the labor hours.