pcv question Options

[wannabegst]

garner was talking about drilling out his pcv valve and i was just wondering what would be the benefits in doing that?

[natedogg]

It allows more crank case pressure to be relieved while the engine is under boost. Normal operation forces the pcv valve to shut when positive pressure is seen at the intake manifold. This means the only route for crankcase pressure to leave is out the breather. The old 'take the breather hose out of the intake pipe and put a filter on it' adage actually works against us here. Though this practice saves the intake pipes from any oil spit up from the valve cover, it hurts us under boost, since the turbo is pulling air from the intake pipe and actually sucking away our unwanted crankcase pressure. I suggest drilling out the pcv and routing it and the breather hose to a filterless (filters clog) hose that drains near the tranny. Make sure the hose is pointing down so any excess valve cover oil will drain rather than clog the line. This allows maximum ventilation under boost or vacuum without having a breather hose to your intake pipe.

If you really want to get crazy with it you could use an automotive grade 12v vaccuum pump controlled by a hobbs pressure switch to suck out the crank case pressure under boost in a similar way to the stock breather hose configuration.