What material are these exhaust valves made from?

These Manley Severe Duty exhaust valves are made from XH-428 material. Manley states this material offers significantly higher tensile strength at high temperatures compared to common alternatives.

How durable are these valves compared to others?

Manley reports that these valves have undergone fatigue testing and endured up to 100 million cycles at 40,000 psi and 1400?F. This is presented as a substantial improvement over competitor valves that failed much earlier in testing.

What is the purpose of the swirl-polished under head areas?

The swirl-polished under head areas, along with the fully machined combustion faces, are designed to optimize airflow into the combustion chamber. This can contribute to improved combustion efficiency within the engine.

Specifications

Brand: Manley Performance
Part #: 11595-8
UPC: 807298050904

Manley SBC 1.6 Severe Duty Exhaust Valves (Set of 8)

Name: Manley SBC 1.6 Severe Duty Exhaust Valves (Set of 8)
Brand: Manley Performance
SKU: manley-performance-manley-sbc-1-6-severe-duty-exhaust-valves-set-of-8-t14-4359563
Price: 332.75 USD
Availability: BackOrder

$332.75

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Manley SBC 1.6" Severe Duty Exhaust Valves (Set of 8). Built from XH-428 material for extreme durability in high-temp gasoline engines.

Key Features

Set of 8 Manley SBC Severe Duty exhaust valves.
Constructed from XH-428 material, offering high tensile strength at elevated temperatures.
Chrome stems and hard tips enhance durability and longevity.
Swirl-polished under head areas and fully machined combustion faces improve airflow.
Tested to endure up to 100 million cycles under high stress and temperature conditions.
Designed for high-temperature gasoline engines.

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About this part

Product Details

Manley Performance is well-known for making strong internal engine components. These Severe Duty? exhaust valves are a prime example, built for demanding gasoline engines that run hot. They are designed to handle the intense stress that valves experience, especially when they bounce on the seat, which can multiply the applied stress significantly.

These valves are constructed from XH-428 material, which Manley states has nearly double the ultimate tensile strength at 1500?F compared to competing EV-8 materials. They've been put through rigorous fatigue tests, enduring up to 100 million cycles at 40,000 psi and 1400?F, which is a notable improvement over competitor parts that failed much sooner. The valves also feature chrome stems and hard tips for added durability, along with swirl-polished under-head areas and fully machined faces to help optimize airflow and combustion efficiency.

This set includes eight exhaust valves, making them suitable for most V8 engine builds. If you're rebuilding a high-performance or racing engine, these valves are built to withstand extreme conditions and offer a long service life.