X3M Competition S58 — stage 1 tune results and daily drivability review

about 2 months ago· 2 posts

Just tuned my 2024 X3M Competition with a BM3 stage 1 map on 98 octane. The S58 engine responds incredibly well to tuning. Stock numbers: 510hp / 600Nm After stage 1: approximately 570hp / 700Nm (estimated from butt dyno and acceleration times) The difference is most noticeable in the midrange — 3000-5500rpm pulls significantly harder. The turbo spool feels quicker and the power delivery is more linear. 0-100 went from 4.1 seconds to what feels like mid 3s. Daily drivability is completely unaffected. In comfort mode the car drives exactly the same as stock. The tune only changes behavior when you get on the throttle. Fuel consumption is identical in normal driving. The S58 is essentially a development of the S55 with a closed-deck block, stronger internals, and a more efficient turbo setup. It responds to tuning even better than the S55 did. Stage 2 with a catless downpipe should push well past 600hp. Anyone else running a tuned X3M or X4M? What tune are you using?

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Replies (2)

Sandra

about 1 month ago#1

Running a tuned X3M Competition as well. I went with MHD stage 1+ on 98 octane and the results are similar to yours. The S58 is a beast of an engine — the closed deck block and forged crank mean the bottom end can handle significantly more power than stock. For stage 2, the catless downpipe makes a huge difference on the S58. The stock cats are very restrictive and removing them frees up a lot of exhaust flow. Expect another 30-40hp on top of stage 1. VRSF and Eventuri both make quality downpipes for the S58. One thing to watch — the S58 runs very hot under sustained load. An upgraded intercooler is worth considering if you do track days or spirited driving in warm weather. The stock intercooler heat soaks quickly.

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Stefan

about 1 month ago#2

The S58 at stage 2 with a catless downpipe and upgraded intercooler is making 620-650hp on some dyno sheets I have seen. That is supercar territory from a compact SUV. The xDrive system handles it well but you will want to upgrade the rear diff fluid to something with higher thermal capacity if you track it. For warranty concerns — any ECU tune will void your powertrain warranty if BMW detects it. BM3 has a feature to flash back to stock before dealer visits, but BMW can sometimes detect that the ECU has been modified even after reflashing. Just something to be aware of.

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