What is a Napier hook on a piston ring?

A Napier hook is a specific design feature on the second piston ring. It's shaped to provide a more positive seal against the cylinder wall, especially during the piston's downstroke, helping to prevent blow-by.

Why is this a bulk pack of 48?

This bulk pack is intended for engine builders or shops that work on multiple engines. It provides a convenient way to have multiple sets of these specific rings on hand for various projects.

What does 'Not CARB approved' mean?

This means the product does not meet the emissions standards set by the California Air Resources Board (CARB). As a result, it cannot be legally sold or shipped to California.

Mahle OE Piston Rings 3021373B - Steel Napier 2nd Ring

Name: Mahle Rings Perf Steel Napier 2nd Ring 3.942in x 1.0MM .136in RW Plain Ring Set (48 Qty Bulk Pack)
Brand: Mahle OE
SKU: mahle-oe-mahle-rings-perf-steel-napier-2nd-ring-3-942in-x-1-0mm-136in-rw-plain-r-t14-47751
Price: 211.87 USD
Availability: BackOrder

Mahle Rings Perf Steel Napier 2nd Ring 3.942in x 1.0MM .136in RW Plain Ring Set (48 Qty Bulk Pack)

$211.87

On Backorder

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

Mahle OE Steel Napier 2nd Ring Set, 3.942in x 1.0MM. This bulk pack is ideal for engine builders needing multiple sets.

Key Features

This is a Mahle OE Steel Napier 2nd Ring Set.
The second ring measures 3.942 inches in bore size, 1.0mm in thickness, and .136 inches in width.
Features a Napier hook design for improved cylinder wall sealing.
Constructed from steel for durability and consistent performance.
Comes as a bulk pack containing 48 individual ring sets.
Not CARB approved; cannot be shipped to California.

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Product Details

The 1.0mm thickness of the second ring in this Mahle OE set is a key design choice for performance engines. This specific ring features a Napier hook, which helps it seal against the cylinder wall more effectively, especially as the piston changes direction. This set comes in a bulk pack of 48, making it a practical choice for shops or builders working on multiple engines or needing spares.

Mahle OE rings are well-built using steel for durability and consistent performance. The 3.942-inch bore size is common in many performance applications, and the .136-inch ring width is standard for this type of performance ring. These rings are designed to work with the piston to maintain a tight seal, preventing combustion gases from escaping into the crankcase and oil from entering the combustion chamber, which is crucial for engine efficiency and power.

Keep in mind that this particular ring set is not CARB approved and cannot be shipped to California. Always refer to your engine's specific service manual for proper installation procedures and ring gap specifications.