Supertech manufactures racing valves in many different materials like Stainless Steel Alloys,
Nimonic, Inconel, Titanium, etc. There are different alloys, heat treatments, and coatings used
for different applications. For most of the alloys Supertech follows the specifications under
SAE standard J775.
STAINLESS STEEL ALLOYS
Made as a one piece forged valve for higher strength and reliability. Supertech uses mostly EV8 (21-4N)
for intake and exhaust valves. Other hard metal alloys may be welded to harden certain areas like the tips,
or seat mating surfaces.
BLACK NITIRIDE COATING
This coating is a hardening treatement that even though it is not widely used as chrome, has several benefits and
is becoming very popular in European and Japanese applications. The microhardness is higher than the stainless steel
base material, keeping good ductility beneath the hard nitrided layer (microharness is 800HV minimum).
Surface finish is smoother than with chromed stems, having less friction between the stem and the valve guide.
The valve seat surface is harder with the nitrided layer, lasting longer with lead free fuels, alcohols, nitro or other
"explosive" mixes. This mataches with any kind of seat material (nodular iron seats, steel powder metals seats, hard
aluminum-copper seats, or beryllium copper seats). Engines reaching higher RPMs take full advantage of these features.
The higher the engine speed, the bigger the power loss due to internal engine friction. The black nitride layer reduces
this power loss due to it's lower friction characteristics. In the worst situations, even with valve to piston contact,
the Black Nitride layer willnot flake or brake because it is ahdered to the base material at a microscopic level.