DESCRIPTION
SSupertech exhaust valve set for the NC MX5. Fits 2.0L as well as 2.3L and 2.5L MZR/Duratec engines.
Price is for a set of 8 exhaust valves, enough to replace all the exhaust valves in one engine.
Head Diameter Options: Choice of 30.0mm (standard) or 31.0mm (+1mm).
Material Options: 31mm valves can be had in either stainless steel with black nitride coating, or inconel. The 30mm valves are only available in stainless/nitride.
Inconel can handle a couple hundred degrees more than the stainless/nitride valve, so we recommend inconel for engines running boost, and/or any high performance engine that is on pump gas.
Note the 30mm stainless/nitride valves can be had in either in flat or dished shape. For the 31mm size, the stainless/nitride option has a flat face, and the inconel valves are dished. This is because a flat face valve increases compression ratio by a very tiny amount, which may be desireable for an all-out naturally aspirated engine build, but for a turbo - which usually when an inconel exhaust valve is recommended - there's no need for that insignificant compression bump as the boost is doing all the job of making power.
* Single groove
* Length: 104.70mm (standard)
* Stem Diameter: 5.48mm
If you're replacing your valves, we recommend also replacing the valve seals and guides at the same time. Supertech makes both of those too, available separately on our site.