Hi, highest 'suck' or negative pressure is on overrun& idle, at this condition crankcase fumes etc are drawn or sucked through the pcv valve and put back in downstream of the throttle. At WOT the pressure upstream and downstream of the throttle are (virtually ambient pressure) identical and therefore the fumes then take the easier path of exiting the rocker cover at the other end and are put back in upstream of the throttle. The higher positive pressure you get at WOT with more blowby past the rings helps compensate for the lack of neg pressure in the inlet tract, ensuring some flow still occurs. For upgrades use the GTT OCC on the PCV circuit . You can also put a small breather filter on the hose from the other end of the rocker cover if you wish. Remember to use a stepped bung to block the hole in the inlet hose aswell.
Best Regards Roland GTT
