What material are these exhaust valves made from?

These Manley Pro Flo exhaust valves are constructed from XH-428 material. This material is chosen for its exceptional strength at high temperatures, offering nearly double the tensile strength at 1500°F compared to common EV-8 materials.

What is the benefit of the swirl-polished under-head area?

The swirl-polished under-head areas, along with fully machined combustion faces, are designed to improve airflow into the cylinder. This can contribute to better combustion efficiency and overall engine performance.

Are these valves suitable for everyday street use or just racing?

While designed for severe duty and racing, their robust construction and high-temperature material make them a durable choice for high-performance street applications as well. They are built to withstand significant stress and heat cycles.

Specifications

Brand: Manley Performance
Part #: 11680-8
UPC: 807298051482

Manley Chevy LS-1 Small Block 2.055 Pro Flo Severe Duty Exhaust Valves (Set of 8)

Name: Manley Chevy LS-1 Small Block 2.055 Pro Flo Severe Duty Exhaust Valves (Set of 8)
Brand: Manley Performance
SKU: manley-performance-manley-chevy-ls-1-small-block-2-055-pro-flo-severe-duty-exhau-t14-4337395
Price: 349.40 USD
Availability: BackOrder

$349.40

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Manley Pro Flo Severe Duty exhaust valves for Chevy LS-1 Small Block engines. Made from XH-428 material for high-temp performance.

Key Features

Fits Chevy LS-1 Small Block engines.
Exhaust valves are made from XH-428 material, offering superior high-temperature tensile strength.
Each valve has a 2.055-inch head diameter and a .3133-inch stem diameter.
Features chrome stems and hard tips for added durability.
Swirl polished under-head areas and fully machined combustion faces improve airflow.
Tested to endure up to 100 million cycles at 40,000 psi and 1400°F.

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About this part

Product Details

Manley's Pro Flo Severe Duty exhaust valves are built from XH-428 material, a choice that offers nearly double the ultimate tensile strength at 1500°F compared to competing EV-8 materials. These valves are specifically designed for high-temperature gasoline engines, ensuring they can handle the demanding conditions found in performance applications. Each valve features a 2.055-inch head diameter and a .3133-inch stem diameter, with an overall length of 4.874 inches.

The construction includes chrome stems and hard tips, which add to their durability and longevity. For improved airflow and combustion efficiency, the under-head areas are swirl polished, and the combustion faces are fully machined. Rigorous fatigue testing shows these valves can endure up to 100 million cycles at 40,000 psi and 1400°F, significantly outperforming competitors that fail much sooner. This makes them a solid option for anyone rebuilding or upgrading their LS-1 small block Chevy engine.