The first-ever X3M and X4M made headlines in the BMW world this month joining the X5M and X6M completing BMW’s four aggressive SAV and SAC lineup. The X3M is the first in its class since the X3 was created, which is incredible, but what has people buzzing is what is underneath the hood. BMW has dropped a new, high performance engine, the S58. The S58 engine will replace the iconic S55.

Is the S58 A Legend Already? 

As we can see the S58 will be built around the B58 engine. The B58 was introduced in 2015 and is basically used in every BMW up until 2019 which includes the latest 3, 5, 7 and X7 models. It’s even offered in the new Z4, which shares similarities with the Toyota Supra. This engine even powers a few M-badged models such as the Z4 M40i and M340i. That is because BMW’s such as the M2 Comp, M3 and M4 draw their power from the S55, the high-performance version of the old N55. The S58 will replace all S55 engines across the board.

Even though the S58 is not a completely new engine, it will take performance to a whole new level and optimizes M-badged BMW’s to comply with emission regulations. This became a huge issue for the S55 engine. In early 2018, BMW announced they would stop production of the M3 in May 2018. Production was stopped because the current M3 would not be able to comply with the new emissions regulations from the Worldwide Harmonized Light Vehicles Test Procedure (WLTP). The current M3 needed a particular filter and installing one on the S55 needs a critical amount of BMW re engineering. BMW chose to wait for the S58. The S58 has everything it will need to pass the WLTP regulations for the next several years. 

The S58 has big improvements when it comes to power. The S58 will push out 473 hp and 442 lb-ft in the first-ever X3M and X4M and 503 hp in the Competition models. This is the most powerful 6-cylinder engine BMW has produced thus far. Since this is the first-ever X3M, there is no way for us to compare it to anything, but we can take a look at the S55 that is offered in the M3 and M4. The S58 offers 55 more horsepower and 36 lb-ft in the regular M3 and M4, but in the M3 CS is adds an extra 26 horsepower. The M4 GTS still reigns superior at 493 horsepower and 443 lb-ft, BUT! The Competition version of the S58 adds an extra 10 horsepower at 503 horsepower. Very safe to say there is a ton of room for improvement. 


The S58 Has Major Shoes to Fill

The S55 replacement is harder than it sounds. The iconic S55 was featured in an extensive list of high performance BMW's which includes the M2 Competition. The S55 is also found under the hood of the M3 and M4 plus their Competition models which are rated at 425 and 444 horsepower, respectively. The M3  CS and M4 CS has 453 horsepower while the M4 GTS is peaked at 493 horsepower. 

The Competition-spec S58, needless to say, is already more powerful than the S55. BMW will need to add more than an extra ten horsepower for the limited-edition M3 or M4. A successor to the M3 CS will need at least 520 horsepower, while the next generation M4 GTS will be pointless without at minimum 550 horsepower. We still do not know if the S58 is capable of this type of power, but BMW put an immense amount of technology into this engine to make it happen.

The S58 will continue to have two mono-scroll turbochargers. The S58 will feature upgraded compressors and an intercooler powered by a low-temperature circuit. There is also a new flow-optimized air intake system that will reduce pressure loss and an electronically controlled wastegate that improves responsiveness. Maximum injection pressure has increased from 200 to 350 bar because of the new high-precision injection technology. This optimizes more efficiency for mixture preparation which reduces emissions at high speeds and under full throttle. The Valvetronic fully variable timing and the Double-Vanos variable camshaft timing technologies also help the increased output and reduced emissions. 

A much powerful engine needs better cooling. BMW created larger radiators, added a new engine oil cooler, and added a separate transmission oil cooler. A map-controlled oil pump softens the internal components during high lateral acceleration. We can thank the new oil sump with two chambers and an integrated suction channel. All of the technology is there and the last task is for BMW to prove the engine's capability and reliability in the first-ever X3M and X4M before forcing the engine to deliver more power into new and upcoming models. 


Is the S58 Going Into Other M Models?

The S58 will not only be available in the X3M and X4M. This engine will be seen in the next-generation M3 and M4. We are expecting this release to be announced at the end of this year. The power ratings are probably going to remain unchanged. The M3 and M4 are expected to have 473 horsepower and 442 lb-ft while the Competition models are expected to be close to 503 horsepower. The M3 Competiton and M4 Competition are expected to debut with the regular models just like it happened with the X3M and X4M. This is such a big deal because the Competition package was a facelift-like upgrade that replaced the regular model. 

The next-generation M2 could potentially feature the S58 and will be more powerful than the M2 Competition. If the M3 and M4 boast 473 horsepower, there is a very good chance the new M2 will exceed the old M3 and M4 output-wise. The base M2 could push out close to 430 horsepower, while the M2 Competition could push out 450 horsepower. 


Will the S58 Replace The V-8?

This is a strong possibility but, vehicles such as the X5M and X6M depend on the twin-turbo 4.4-liter V-8. On the other hand, this will need to change at some point so it can comply with new emissions regulations. BMW may still have the resources to create a new V-8,  but could replace it with the S58. It is a strong possibility because the S58 is capable of pushing out 500 horsepower. It is not going to be long until BMW has the capability for the 3.0-liter to match the very powerful V-8.