What material are these Mahle pistons made from?

These Mahle MS pistons are forged from a 4032 aluminum alloy. This material is chosen for its strength and favorable thermal expansion characteristics, making it well-suited for high-performance engine applications.

What is the compression ratio of these pistons?

These pistons feature a 10.2:1 compression ratio. This is a common and effective ratio for performance-oriented BMW S65 4.0L engines, balancing power output with pump fuel compatibility.

Are these pistons legal for use in California?

No, these pistons are not CARB approved and cannot be shipped to California. Please check local regulations regarding emissions compliance for engine modifications.

Mahle MS BMW S65 4.0L Forged Pistons Set 197843342

Name: Mahle MS BMW S65 B40 4.0L 92.50mm x 27.3mm CH 2.1cc 372g 10.2CR Pistons (Set of 8)
Brand: Mahle
SKU: mahle-mahle-ms-bmw-s65-b40-4-0l-92-50mm-x-27-3mm-ch-2-1cc-372g-10-2cr-pistons-se-t14-211339
Price: 1426.16 USD
Availability: BackOrder

Mahle MS BMW S65 B40 4.0L 92.50mm x 27.3mm CH 2.1cc 372g 10.2CR 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 BMW S65 B40 4.0L 92.50mm x 27.3mm CH 2.1cc 372g 10.2CR Pistons (Set of 8)

Key Features

Set of 8 Mahle MS forged pistons for BMW S65 4.0L engines.
Forged from 4032 aluminum alloy for strength and thermal stability.
92.50mm bore size with a 10.2:1 compression ratio.
Each piston weighs 372g with a 27.3mm compression height.
Features a 2.1cc dish volume and a 21mm pin diameter.
Designed for a 75.2mm stroke and 140.7mm rod length.

These Mahle pistons are designed for BMW S65 4.0L engines. Please verify compatibility 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

Forged from 4032 aluminum alloy, these Mahle MS pistons are built for high-performance BMW S65 4.0L engines. The 92.50mm bore size and 10.2:1 compression ratio are specifically chosen to optimize power output for this V8 powerplant. Each piston weighs in at 372g, with a 27.3mm compression height and a 2.1cc dish volume, ensuring precise balance and performance within the engine's rotating assembly.

Mahle's expertise in piston design means these are not just replacements, but upgrades designed to handle the demands of performance driving. The 4032 aluminum alloy offers a good balance of strength and thermal expansion properties, making it suitable for engines that see regular hard use. The 21mm pin diameter is standard for many performance applications, and the 75.2mm stroke and 140.7mm rod length are key dimensions for calculating the correct compression height and overall engine geometry.

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. Always refer to your engine builder's specifications and the manufacturer's installation instructions for proper fitment and assembly procedures.