Originally Posted by
Mirek
I'm sorry, my English is probably not good enough, but I don't know what You mean by valveflow.
Anyway I don't know the exact WRC rules.
AFAIK the problem with S2000 valves was that they had to be made of steel, i.e. they were heavy. With such high engine speed the valve springs had to cope with very high valve inertia. For me it is an example of a wrong idea how to make things cheaper.
Dim: That's exactly what I though - if the higher top speed as the only clear benefit is worth the effort to make the engine reliable at so high rpm. Maybe they simply set the limiter to lower value than what is allowed by the rules.