Supertech Valves +1mm oversized D-series valves are made in 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).

Available for the following D-series engines:

• 88-91 Civic/CRX 1.5liter D15Bx
• 88-91 Civic/CRX Si 1.6liter D16A6
• 92-95 Civic SOHC VTEC D16Z6
• 96-00 Civic SOHC non-VTEC D16Y7
• 96-00 Civic SOHC VTEC D16Y8

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