What is the compression ratio with these pistons?

These Mahle MS pistons feature a 12.2cc dish volume, which results in a 12.2:1 compression ratio when installed with the appropriate crankshaft and connecting rod for the BMW S65 B40 4.0L engine.

What materials are these pistons made from?

The pistons are constructed from 4032 aluminum alloy. This material is chosen for its strength and resistance to thermal expansion, making it suitable for high-performance engine applications.

Are these pistons compatible with all BMW S65 engines?

These pistons are specifically listed for the S65 B40 4.0L engine variant. It is important to confirm compatibility with your specific engine code and build specifications before purchase.

Mahle Forged Pistons S65 B40 4.0L 92.00mm Set of 8

Name: Mahle MS BMW S65 B40 4.0L 92.00mm x 27.3mm CH 12.2cc 366g 12.2CR Pistons (Set of 8)
Brand: Mahle
SKU: mahle-mahle-ms-bmw-s65-b40-4-0l-92-00mm-x-27-3mm-ch-12-2cc-366g-12-2cr-pistons-s-t14-211340
Price: 1426.16 USD
Availability: BackOrder

Mahle MS BMW S65 B40 4.0L 92.00mm x 27.3mm CH 12.2cc 366g 12.2CR Pistons (Set of 8)

$1426.16

On Backorder

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

Mahle MS forged pistons for BMW S65 B40 4.0L engines. Set of 8.

Key Features

Fits BMW S65 B40 4.0L engines.
Set includes 8 forged pistons.
Piston bore is 92.00mm.
Compression height is 27.3mm.
Features a 12.2cc dish volume for a 12.2:1 compression ratio.
Constructed from durable 4032 aluminum alloy.

These pistons are specifically designed for the BMW S65 B40 4.0L engine. Please verify fitment with your specific vehicle application.

⚠️ CA WARNING: This product can expose you to chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm. Learn more

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Product Details

If you're rebuilding the heart of your BMW S65 B40 4.0L engine, a solid set of pistons is crucial for performance and reliability. Mahle's MS series pistons are a well-built choice for this high-performance V8, designed to handle the demands of a refreshed or upgraded engine. These pistons are specifically sized for the S65 B40, with a 92.00mm bore and a 27.3mm compression height, ensuring they fit right into your engine build.

Crafted from 4032 aluminum alloy, these pistons offer a good balance of strength and lighter weight compared to cast alternatives. This alloy is known for its durability and resistance to thermal expansion, which is important for maintaining consistent performance under load. The set includes eight pistons, each weighing 366g, and features a 12.2cc dish volume, resulting in a 12.2:1 compression ratio when paired with the correct components. This compression ratio is ideal for maximizing power output from the 4.0L V8, especially when using premium fuel.

When undertaking an engine rebuild of this caliber, it's important to ensure all components are properly matched. These pistons are designed to work with a 75.2mm stroke crankshaft and a 140.7mm connecting rod, using a 21mm pin. Remember that these pistons are not CARB approved and cannot be shipped to California. Always refer to the manufacturer's installation instructions for precise details on assembly and break-in procedures to get the most out of your Mahle pistons.