B58 High Performance Valve Seats

5150 MoldStar 90 High Performance Valve Seat Set – BMW & Toyota B58

The 5150 MoldStar 90 Valve Seat Kit is designed for high horsepower BMW and Toyota B58 cylinder heads operating under extreme boost, cylinder pressure, exhaust temperature, and RPM.

Each complete kit includes 12 intake and 12 exhaust valve seats manufactured from MoldStar 90, a premium beryllium-free copper alloy selected for its combination of excellent thermal conductivity, strength, wear resistance, and high-temperature performance.

Why Replace the Factory Valve Seats?

On a factory B58, the OEM valve seats are designed around factory power, RPM, temperature, emissions, and durability requirements. Once the engine is pushed into serious racing territory, the demands placed on the valve and seat increase dramatically.

The valve seat does much more than provide a surface for the valve to close against. It is responsible for maintaining the seal of the combustion chamber while also providing an important path for transferring heat out of the valve and into the cylinder head.

This becomes especially important on high-boost racing engines where exhaust gas temperature and cylinder pressure are significantly increased.

Why MoldStar 90?

Heat management is one of the biggest advantages.

Every time the valve closes against the seat, heat is transferred from the valve into the seat and then into the surrounding cylinder head. MoldStar 90's copper-based construction provides excellent thermal conductivity, helping remove heat from the valve more efficiently.

Controlling valve temperature becomes increasingly important in applications involving:

High boost and cylinder pressure
High exhaust gas temperatures
Large turbochargers
Extended high-RPM operation
Drag and roll racing
Road and circuit racing
Upgraded camshafts and valve springs
Oversized performance valves
Fully CNC-ported racing cylinder heads
Improved Valve Sealing

At extreme cylinder pressures, maintaining a precise valve-to-seat seal is critical. A compromised valve job can result in lost compression, reduced combustion efficiency, excessive valve temperature, and eventually valve or seat damage.

Properly machined MoldStar 90 seats provide an excellent foundation for a precision performance valve job and help maintain consistent sealing under demanding operating conditions.

Better Heat Transfer = Better Valve Protection

The exhaust valve is one of the most thermally stressed components in a turbocharged engine. A significant amount of its heat is transferred through the valve face when it contacts the valve seat.

Improving this heat-transfer path can help control valve temperatures and is particularly beneficial on B58 engines experiencing sustained high EGT and increased boost.

This is why we consider the valve seat an important component when building a complete competition B58 cylinder head, rather than focusing only on larger valves, stronger springs, and aggressive camshafts.

Designed for Serious B58 Builds

We recommend MoldStar 90 valve seats when building B58 cylinder heads for applications where power, boost, RPM, and operating temperature have moved substantially beyond factory levels.

They are also an excellent choice when installing oversized valves or replacing damaged factory valve seats, allowing the machine shop to establish the correct seat geometry specifically for the new valve and intended application.

Kit Includes
12 x Intake Valve Seats
12 x Exhaust Valve Seats

Beryllium-Free Copper Alloy
Excellent Thermal Conductivity
High Strength and Wear Resistance
Designed for High-Boost & High-RPM Applications
Ideal for Oversized Performance Valves
Excellent Foundation for Precision Multi-Angle Valve Jobs
Designed for BMW & Toyota B58 Cylinder Heads
Professional Machining Required

MoldStar 90 valve seats require professional cylinder-head machining and installation. Correct interference fit, seat depth, concentricity, valve-seat width, and final valve-job geometry are critical.

For maximum-effort B58 racing engines, we recommend combining MoldStar 90 seats with upgraded valves, performance valve guides, springs and retainers, performance camshafts, and a professionally CNC-machined cylinder head.

When you're pushing extreme boost and power, keeping the valves cool and the combustion chamber properly sealed becomes critical. MoldStar 90 seats give the B58 cylinder head the thermal management and valve-seat foundation needed for serious racing applications.

BMW B58 Gen 1 Applications:

1 Series

2016-2019     F20/F21     M140i

2 Series

2016-2019     F22/F23     M240i

3 Series

2015-2019     F30/F31     340i / 340i xDrive
2016-2019     F34     340i GT / 340i GT xDrive

4 Series

2016-2020     F32/F33/F36     440i / 440i xDrive

5 Series

2016-2019     G30/G31     540i / 540i xDrive

6 Series

2017-2019     G32     640i GT / 640i GT xDrive

7 Series

2015-2019     G11/G12     740i / 740i xDrive

X3 Series

2017-2019     G01     X3 M40i

X4 Series

2018-2019     G02     X4 M40i

BMW B58 Gen 2 Applications:

3 Series

2019-Present     G20/G21     M340i / M340i xDrive

4 Series

2020-Present     G22/G23/G26     M440i / M440i xDrive

Z Series

2019-Present     G29     Z4 M40i

5 Series

2020-Present     G30/G31 LCI     540i / 540i xDrive

6 Series

2020-Present     G32 LCI     640i GT / GT 640i xDrive 

7 Series

2019-Present     G11/G12 LCI     740i / 740i xDrive

X3 Series

2020-Present     G01     X3 M40i

X4 Series

2020-Present     G02     X4 M40i

X5 Series

2018-Present     G05     X5 xDrive40i

X6 Series

2019-Present     G06     X6 xDrive40i

X7 Series

2018-Present     G07     X7 xDrive40i

ALPINA B58 Gen 2 Applications:

B3 Series

2020-Present     G20/G21     B3

B4 Series

2022-Present     G22     B4

B5 Series

2020-Present     G30     B5

XB7 Series

2020-Present     G07     XB7

Toyota B58 Gen 2 Applications:

A90 / A91 Supra

2020-Present     GR Supra 3.0    
2020-Present     GR Supra 3.0 Premium    
2021-Present     GR Supra 3.0 A91 Edition