Technically, when you install a catch-can, you're modifying the PCV system to filter out the oil mist/vapour from the top of the head. As the name suggests, the "Positive Crankcase Ventilation" system is there to relieve pressure differences between the head and the inlet manifold. If you don't make sure the system is installed correctly, you'll end up creating too much back-pressure in the head, and that's when you start to see oil seeping through the rocker-cover gaskets.Dras wrote:A pcv valve does not hurt performance, there is no good reason why you would want to get rid of it.mattman wrote:no you dont pcv valve goes in the bin but this depends on how you set up the catch alsoDras wrote:That is just crap. You use a catch can together with a pcv valve.mattman wrote:pcv valve you dont need it lol get a catch can a lot better for the motor.
The pcv valve will stop excess oil being sucked out of the heads while the engine is idling (as this is when the vacuum is greatest). Having a catch can just means that the oil will be caught in the catch can rather than burnt by the motor but with no pcv, oil will still be sucked out of the heads for no good reason.
Removing the pcv valve will only result in having to top up the oil more frequently in your motor.
There are benefits from keeping the crankcase at a vacuum but this requires a vacuum pump, a dry sump setup, catch cans that will recycle caught oil and some serious effort to make sure that the motor doesn't suffer from oil starvation. Simply replacing the pcv valve with a catch can is just silly.
Removing the pcv valve is illegal. It is considered an emissions control device and therefore cannot be modified without having the car engineered.
I run 2 custom built catch cans and a pcv in my setup, I have put considerable research into understanding how the whole system works but if you are still convinced that removing the pcv valve is the way to go, please enlighten us as to why you think it is better to run an FTO without a pcv valve and what we can hope to gain without one. Some punctuation and correct grammar would also be nice.
The way your PCV gets set-up depends on whether you're boosted or whether you're just trying to make the engine cleaner. It is quite easy to plumb a return line and oil check valve back into the sump, filtering the oil vapour out of the PCV, that would otherwise go to the intake air, and replacing it in the sump (where it belongs).
Engines with higher compression ratios will find that there will be a lot of "blow-by" caused by excessive crank-case pressure as the combustion gasses escape past the piston rings and into the rest of the motor. This is also dependant on how well your motor has been run-in, as that will determine how much gas can escape past the rings. In my case, the PCV coupled with the EGR system creates a nice, thick sludge that coats the internals of the inlet manifold. You guys won't need to worry about this too much, as my EGR system is inherently dirtier due to the excess carbon created when burning diesel. Unless your vehicle is running rich, there's no reason to remove the PCV, or even to vent it really.
