Manley Performance Severe Duty Exhaust Valves – Set of 8 | Multiple Fitments (11661-8) Manley Performance

Severe Duty / Pro Flo Stainless Steel Exhaust Valves – Set of 8 by Manley Performance

The Severe Duty® series of valves is the Manley signature in the performance and racing industry. Exhaust material XH-428 and intake material NK-844 is offered by no competitor in the world. And no pair of materials show such clear dominance over all others. Ultimate tensile strength of XH-428 at 1500°F is nearly double the competitors’ EV-8. At 1000°F the Manley NK-844 displays more than four times the ultimate tensile of the competition’s best intake material.

In addition to the vastly superior strength and fatigue characteristics of Manley NK-844, our exclusive intake material exhibits an uncanny ability to resist chordal fractures. In an excellent sealing combustion chamber, the intake valve is actually deformed by the fuel explosion and pushed up into the port. The effect of this continuous deformation on competitors’ material eventually is a chordal fracture propagating from the circumference of the valve and quickly becoming a missing pie-shaped piece. Manley NK-844 is the absolute best choice of material to combat disastrous chordal fractures.

Further proof of the superiority of the Manley Severe Duty® valves is evident in our comprehensive fatigue tests. In normal operation where valve float is non-existent, a valve will experience 20,000 to 25,000 lbs of applied stress. However, when valves bounce on the seat the stress immediately soars to 40,000 to 60,000 lbs. Manley exhaust valves (at 40,000 psi and 1400°F) ran to 100,000,000 (one hundred million) cycles while competitors’ offerings failed at 100,000 cycles. That’s 1000 times better fatigue life.

Features

• Head Diameter : 1.590
• Stem Diameter : .3136
• Installed Height : Stock
• O/A Length : 4.923
• Tip Length : .160
• Underhead Angle/Radius : 25° x 7/16”
• Margin : .070
• Seat Width : .115
• Top of Head : 18° Dish
• Wgt/Grams : 94
• XH-428 Stainless Exhaust Material
• Chrome Stems and Hard Tips
• Swirl Polished and Fully Machined
• O.E. Style Radius Keeper Grooves

Benefits

• Intakes are “Pro Flo” for Improved Flows
• The absolute best choice of material to combat disastrous chordal fractures

Please Note: The image provided is generic and may not be an accurate representation of the product you will receive

Applications

• 2008 – 2013 Chevrolet Corvette
• 2010 – 2015 Chevrolet Camaro SS
• 2009 Pontiac G8 GXP
• 2014 – 2017 Chevrolet SS

What’s In The Box?

• 8 – Exhaust Valves

Warranty

• Manley products, due to their intended use, are sold without warranty.