Supertech Mazda Miata 1.8L Black Nitrided Exhaust Valve - +1mm Oversize - Set of 8

Supertech MAEVN-1206-8 – +1 mm Oversize Black-Nitrided Exhaust Valve Set (Mazda BP 1.8 L)

Supertech’s MAEVN-1206-8 kit supplies eight +1 mm oversize exhaust valves for the 1.8 L Mazda BP engine found in the MX-5/Miata (1994-2005) and Ford Escort GT. Each valve is forged from 23-8 N stainless steel and finished with a Black Nitride coating, improving heat resistance, reducing stem-to-guide friction, and boosting exhaust-flow capacity.

Key Features

• +1 mm head diameter (29 mm) – larger curtain area increases exhaust flow, supporting higher power at elevated RPM.

• Black Nitride surface (~52 HRC) reduces wear and lowers friction for better guide life and valve stability.

• One-piece forged stainless construction delivers superior fatigue strength and crack resistance under extreme temperatures.

• Single-groove keeper is compatible with most Supertech and OEM spring/retainer sets.

• Direct fit after minor seat enlargement—ideal for ported heads or builds targeting higher exhaust throughput.

Technical Specifications