Mahle MS BMW S65 B40 4.0L 92.50mm x 27.3mm CH 12.2cc 372g 12.3CR Pistons (Set of 8)

If you're rebuilding the heart of your BMW S65 B40 4.0L engine, selecting the right pistons is critical for performance and reliability. These Mahle MS series pistons are forged from 4032 aluminum, a material known for its strength and resistance to thermal expansion, making them a solid choice for high-performance applications where precision is key. Each piston measures 92.50mm in bore diameter and features a 27.3mm compression height, designed to work with the engine's specific stroke and rod length for optimal valve timing and piston-to-head clearance.

The 12.2cc dish volume contributes to a 12.3:1 compression ratio, which is an updated figure that can help extract more power from your engine, especially when paired with appropriate tuning. Weighing in at 372 grams each, these pistons are well-balanced for smooth operation. Mahle's reputation for well-built engine components means you can trust these pistons to handle the demands of a performance-oriented S65 engine, whether for track use or spirited street driving. They are designed to fit right into the S65 block, simplifying the rebuild process.

This set includes eight pistons, enough for a complete engine rebuild. Please note that these pistons are not CARB approved and cannot be shipped to California. It's always recommended to consult with your engine builder or a qualified mechanic to ensure these pistons meet the specific requirements of your build and to follow proper installation procedures.