Platform Guides
BMW B58 Tuning Guide: M340i, M240i & GR Supra
· 1 min read · PTEB Tuning
The B58 3.0-litre turbo six powers the M340i, M240i, 540i, X3 M40i, Z4 M40i — and Toyota's GR Supra. It's one of the most tune-friendly engines on the road.
Why the B58 responds so well
The B58 has a strong closed-deck block, a single twin-scroll turbo and efficient cooling. BMW calibrates it conservatively from the factory, so a custom tune adds significant mid-range torque on standard hardware.
Stage 1 and Stage 2
Stage 1 is software only and transforms how the car pulls in the mid-range. Stage 2 typically adds a downpipe and an upgraded intercooler to keep intake temperatures under control on longer runs and hot Australian days.
Flex fuel takes the B58 further again, because E85's cooling effect and knock resistance let the calibration run more timing and boost.
Don't forget the ZF8
The ZF 8-speed automatic is strong, but its factory torque limits and shift logic are set for a stock engine. A TCU calibration raises those limits and speeds up shifts so the gearbox works with the tune, not against it.