Supertech +1mm oversized valves are made from one piece forged stainless steel. Intake valves in +1mm o/s are made in SAE EV8 (UNS S63008) and +1mm o/s exhaust valves are made from Inconel 575.

Inconel 575 is a Nickel based alloy material used for exhaust valves in engines that reach very high temperatures and its use is growing with the application of turbos and superchargers. These valves are hollow and filled with Sodium. This will ensure cooling of the valve by removing heat from the head of the valve to the stem, providing better temperature distribution, and lowering head temperature.

Supertech Performance apply's different heat treatments to this material to obtain different hardness and ductility in accordance to application and budget (Street Performance or Heavy Duty Racing).

Features

• The microhardness is higher than the stainless steel base material, keeping good ductility beneath the hard nitrided layer (microhardness is 800HV minimum)
• Surface finish is smoother than with chromed stems, having less friction between stem and guide.
• Valve seat surface is harder with the nitrided layer, lasting longer with lead free fuels, alcohols, nitro or other "explosive" mixes. Matches any kind of seats (nodular iron seats, steel powder metal seats, hard aluminum-copper seats or beryllium copper seats).
• Higher rpm's engines take full advantage of all previous 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 less valve-guide friction.
• The nitrided layer is adhered to the base material at a microscopic level, so does not"flake" or brake when the valves bend due to impacts with the pistons.
• The Black Nitride applies to the whole valve while the chrome coating is only applied to the stem.
• 8 x 35mm (+1) black nitride intake valves
  Standard is 34mm
• 8 x 31.5mm  (+1) Iconel exhaust valves
  Standard is 30.5mm

Sold as a 16pc set (8 intake / 8 exhaust valves)