Vented Rocket cover

[Weq]

hi all, i've seen on some hi-powered apps they have a vented rocket cover (don't bother about talking about the PCV i know how that works)

See this is the your problem. You DONT know ANYTHING about the PVC system is u think this isnt related.

Positive Crankcase Ventilation.

The head is connected to the crank case (bottom end) via many oil passages. as pressure builds, it builds in the topend of the motor. These ports are useful in hi-po setups. Or setups were ring-gaps/piston to wall are kept a little larger, increasing pressure inside the motor. These help evacuate the increased gas volume, quickly and efficently.

On a stock motor with good compression, its just a little bling. A normal catch-can setup will have the same effect.