
Not so with the new S58 powering the F97 X3M and F98 X4M (and upcoming G80 M3). That means the block is different, the bore x stroke ratio, as well as the engine internals:
Engine | Displacement | Bore | Stroke | Application |
---|---|---|---|---|
S58 | 2993cc | 84mm | 90mm | X3 M/X4 M/G80 M3 |
B58 | 2998cc | 82mm | 94.6mm | 2er/3er/4er |
S55 | 2979cc | 84mm | 89.6mm | F80 M3/F82 M4 |
N55 | 2979cc | 84mm | 89.6mm | 2er/3er/4er |
S63 V8 | 4395cc | 89mm | 88.3mm | M5/M6/X5 M/X6 M |
N63 V8 | 4395cc | 89mm | 88.3mm | 5er/6er |
Why is BMW increasing the bore and reducing the stroke in the S58? Well, it may be because they intend to rev it out a bit as the press release states a forged crank and redline of 7200 rpm.
Piston speed at 7200 rpm with 90mm stroke: 4251.96 FPM
Piston speed at 7200 rpm with 94.6mm stroke: 4469.29 FPM
It is still an undersquare design but they did reduce stroke by almost a full 5mm. BMW is reducing stress at higher RPM a bit.
To make up for the lost displacement from reducing the stroke, they increased the bore by 2mm. Is this a good thing? Traditionally in BMW M language it means thin cylinder walls. It is too early to know for sure but based on the photos of the block it certainly looks like BMW left enough material for it to take some punishment.
BMW also lowers the compression ratio for the S58 to 9.3:1 from the 11.0:1 in the B58. That is quite the drop meaning expect big boost up top. Response down low will not be quite as good but this is supposed to be an M motor that revs for power, right?
BMW's dynograph for the Competition version is interesting showing peak power at 6000 rpm which holds to redline but teh the torque curve also drops at 6000 rpm:

What other changes?
- 350 bar fuel pressure
- Revised intake
- New oil pan
- New oil cooler
- Revised intercooler
- 3D printed cylinder head
BMW touches on the new head:

BMW could do the same here although it is unlikely due to the X3M/X4M and G80 M3 sharing all wheel drive and the same transmission. The wild card is the G80 M3 pure.
The 8-speed automatic limits BMW to 7200 rpm despite peak power said to come at a 7300 rpm redline. The 'Pure' edition of the M3 will have a manual transmission so it is entirely possible we will see a higher revving S58 variant in it. That would be a nice nod to classic M fans but do not get your hopes up.
Regardless, the S58 is not just a B58 with bigger turbos and more boost that revs a bit higher. BMW actually made some significant changes.

























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