GSC Power Division 2091-12 Super Alloy Exhaust Valves STD for Toyota/BMW B58/S58

Vehicle Fitment

• 2020 Toyota GR Supra (A90, B58B30M1, 3.0L Turbocharged I6, RWD)
• 2021-2026 Toyota GR Supra (A91, B58B30O1, 3.0L Turbocharged I6, RWD)
• 2016-2026 BMW 340i (F30, B58B30M0, 3.0L Turbocharged I6, RWD/xDrive)
• 2019-2022 BMW X5 xDrive40i (G05, B58B30M1, 3.0L Turbocharged I6, AWD)
• 2020-2022 BMW X5 sDrive40i (G05, B58B30M1, 3.0L Turbocharged I6, RWD)
• 2020-2022 BMW X6 xDrive40i (G06, B58B30M1, 3.0L Turbocharged I6, AWD)
• 2020-2022 BMW X6 sDrive40i (G06, B58B30M1, 3.0L Turbocharged I6, RWD)
• 2019-2022 BMW X7 xDrive40i (G07, B58B30M1, 3.0L Turbocharged I6, AWD)
• 2021-2026 BMW M3 (G80/G81, S58B30T0, 3.0L Twin-Turbo I6, RWD/xDrive)
• 2021-2026 BMW M4 (G82/G83, S58B30T0, 3.0L Twin-Turbo I6, RWD/xDrive)
• 2023-2026 BMW M2 (G87, S58B30T0, 3.0L Twin-Turbo I6, RWD)

Fitment Notes

• Fits the Toyota B58B30M1/B58B30O1 and BMW B58B30M0/B58B30M1 naturally turbocharged inline-6 platforms, as well as the BMW S58B30T0 high-performance twin-turbo inline-6 found in the M3, M4, and M2
• Standard (STD) 28.5mm head diameter - confirms heads have not been previously machined for oversized seats before ordering
• Sold as a set of 12 - one complete engine set for the inline-6 (2 exhaust valves per cylinder x 6 cylinders)
• Super Alloy material is specifically engineered for high-horsepower, high-EGT builds; for builds with less aggressive modifications, the standard stainless version may also be available separately

Features

• Exotic Super Alloy construction rated to sustain exhaust gas temperatures up to 2000°F - purpose-built for high-horsepower, high-boost B58 and S58 applications where standard valves are prone to heat-related failure
• Chrome polished valve stems provide a smooth, durable finish that reduces friction and oil retention against the valve guide, delivering extended service life and improved lubricity - especially when paired with GSC Manganese Bronze valve guides
• Swirl polished valve heads optimize exhaust gas flow across the valve face, supporting combustion efficiency and peak power output in both stock-turbo and upgraded-turbo configurations
• Back-cut head design reduces overall valve mass, enabling higher RPM capability, increased boost pressure tolerance, and compatibility with aggressive camshaft profiles without raising valve spring seat pressures
• Maximized under-head dish removes additional mass while preserving full structural integrity under sustained high-temperature and high-pressure conditions
• Precision-adjusted valve tip lengths minimize tipping requirements during installation, maintaining correct valvetrain geometry and reducing setup time when dialing in valve lash
• Engineered keeper groove geometry balances intake and exhaust spring pressures across the valvetrain, reducing reliance on valve spring shims and optimizing performance from GSC spring and retainer kits
• Valve tips hardened or stellite-tipped to within 5 Rockwell C of the rocker or tappet contact surface, minimizing tip wear over the full service life of the valve
• Less face distortion under extreme conditions than competing tested designs, ensuring superior sealing and consistent performance throughout the life of the valve
• Designed, machined, and flow tested in-house on CNC machining centers using advanced 3D FEA and real-world flow simulation software validated in the specific B58/S58 application

Specifications

• Position: Exhaust (set of 12 - complete engine set for inline-6)
• Valve Head Diameter: 28.5mm (STD / Standard Size)
• Valve Stem Diameter: 6.0mm
• Overall Valve Length: 100.1mm
• Material: Super Alloy (exotic high-temperature alloy, 2000°F rated)
• Stem Finish: Chrome polished
• Head Finish: Swirl polished with back cut; maximized under-head dish
• Application Engines: Toyota B58B30M1/B58B30O1 (3.0L Turbocharged DOHC I6); BMW B58B30M0/B58B30M1 (3.0L Turbocharged DOHC I6); BMW S58B30T0 (3.0L Twin-Turbo DOHC I6)
• Quantity per Set: 12

Included Components

• 12x GSC Power Division Super Alloy Chrome Polished STD Exhaust Valves (28.5mm head, 6.0mm stem, 100.1mm length)

Product Description

The GSC Power Division 2091-12 is a complete set of twelve standard-size (28.5mm) Super Alloy exhaust valves engineered for the Toyota B58 and BMW B58/S58 turbocharged inline-6 engine family. On the Toyota side this covers the 2020 GR Supra A90 (B58B30M1) and the 2021-2026 GR Supra A91 (B58B30O1). On the BMW side it covers the 2016-2026 340i (F30, B58B30M0), the 2019-2022 X5/X6/X7 40i variants (B58B30M1), and the full S58-powered lineup: the 2021-2026 M3 (G80/G81), M4 (G82/G83), and 2023-2026 M2 (G87). All of these share the same exhaust valve geometry, making the 2091-12 a single verified set for the entire B58/S58 platform. Built from GSC's exotic Super Alloy rated to 2000°F, these valves are engineered for high-horsepower, high-EGT builds where standard stainless valves cannot reliably survive sustained thermal load.

The B58 and S58 are among the most frequently modified engines in the current performance market, with a large and active tuning community pushing boost pressure, fueling, and power output well beyond factory levels. The GSC 2091-12 directly addresses the exhaust valve durability concerns that emerge in these builds by using a Super Alloy material that resists both heat distortion and oxidation at temperatures that standard stainless alloys cannot tolerate. The chrome polished stems reduce guide wear and oil accumulation for smoother valve motion, while the swirl polished and back-cut heads improve exhaust flow and reduce valve mass - supporting higher RPM capability and aggressive cam compatibility without increasing spring seat pressures. GSC's engineered keeper groove geometry and precision tip lengths further ensure correct valvetrain balance and easier installation on the B58/S58's closely spaced 24-valve head layout.

Sold as a complete set of 12 for a full engine rebuild on a standard (uncut) head, the GSC 2091-12 pairs directly with the matching STD intake valves (GSC2092-12), Manganese Bronze exhaust valve guides (GSC3131-12), and Viton exhaust valve stem seals (GSC1089) for a complete performance valvetrain rebuild. This is the top-tier exhaust valve option in GSC's B58/S58 lineup and is the correct choice for any serious high-output build - from heavily modified GR Supra builds running port-injected E85 to S58-powered M3/M4 competition builds pushing 600+ horsepower.