What's the limit of standard zetec valves? I see the focus rs has sodium filled exhaust valves, does anyone know why this is? I'm currently building a zetec turbo and was aiming for 300-320bhp so would standard 2.0 black top valves be ok?

Thanks Billy

 

They would be fine at that power yes, sodium filled dissipate heat better but the standard ones will be fine, you will need to change the springs though.