While finishing installing my supertech double springs today (with the head still on), I noticed that neither my intake, nor exhaust valves are magnetic, which would suggest to me that they're stainless.

Does anyone know what the OEM valves are made of in a BP6D? I've no reason to think these valves should be anything other than OEM, but I didn't buy the engine new from Mazda....

 

I don't know the alloy, but I too discovered that the NB valves aren't magnetic.

 

I have no idea.

But doesn't the added chrome, and silicon, (maybe nickel too?) content in the valve that makes it hard make it non magnetic?

 

BP05 valves from the NA8 are magnetic. NB BP4W/BP6D valves from the VVT heads aren't. Dunno why. They are the same physical shape (at least the 4W exhaust valves are same as 05 exhaust valves), but have different part #'s. Alloy change from ? to ? Would appear to be the only difference.