MAP 4G63 High Performance Valves (DSM / Evo)PART#
These valves feature an undercut stem in the head area. In addition to reducing the valve weight (which provides benefits in opening rate and RPM limits), the radius of the head is such that it significantly improves air/fuel flow. They enjoy great success when used with stock heads, as well as modified versions. Fully swirl polished. Chromed stems and Stellite tips.
Benefits of Black Nitride Coating
Black nitride coating is a hardening treatment that even though it is not as widely used the chrome coating, it has several benefits and is becoming more popular for use in the European and Japanese applications.
- The micro hardness is higher than the stainless steel base material, keeping good ductility beneath the hard nitrated layer (micro hardness is 800hv minimum)
- Surface finish is smoother than with chromed valve stems, having less friction between the stem and guide.
- Valve seat surface is harder with the nitrated layer, lasting longer with lead free fuels, alcohols, nitro or other "explosive" mixes. Mathes any kind of seats (nodular iron seats, steel powder metal seats, hard aluminum-copper seats or beryllium copper seats).
- Higher RPM 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 nitrated layer is adhered to the base material at microscopic level, so it will 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.
- All valves are swirl polished, have stem undercut, a hardened tip, and more.
*Includes 8 intake valves and 8 exhaust valves (1 complete set)