Pro Flo / Severe Duty 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 : 1.560
- Stem Diameter : .3136
- Installed Height : Stock
- O/A Length : 5.208
- Tip Length : .160
- Underhead Angle/Radius : 25° x 7/16”
- Margin : .065
- Seat Width : .110
- Top of Head : 18° Dish
- Wgt/Grams : 93
- Chrome Stems and Hard Tips
- Swirl Polished and Fully Machined
- O.E. Style Radius Keeper Grooves
Benefits
- Improved Flow with “Pro Flo” Underhead
- Best choice of material to combat disastrous
chordal fractures
- 1000 times better fatigue life than competitors
Please Note: The image provided is generic and may not be an accurate representation of the product you will receive
