I don't know for sure. But, gut instinct, I doubt this makes any
significant contribution to cooling. Sounds more like a DPO bodge to get
rid of the PCV valve, no more. For any effective air cooling there would
need to be a continuous stream of cool air entering the valve cover, which
would then require a separate outlet for the warmed air to come out again.
With this vent pipe, the only flow along it will be a (hopefully slow)
passage of blowby gases coming out of the valve cover.
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