run valve cover vent to catch can rather than PCV valve?

[tehdrizzle]

I've been seeing alot of debate on whether to run the PCV valve or if you can just simply run the vent to a catch can or a filter. Currently my car is setup so a tube goes straight from the vent on the back of my valve cover to a catch can with no PCV valve or anything connected to the valve cover at all. Is this okay, or should I set it up so I actually use a PCV valve?

[puppet]

If you don't need to pass any kind of inspections (.gov) I'd leave it just like you have it .. but you have to vent the catch can (as large a hole as practical).

IMO, it's simple and works the best.

[supercrackerbox]

If you don't need to pass any kind of inspections (.gov) I'd leave it just like you have it .. but you have to vent the catch can (as large a hole as practical).

IMO, it's simple and works the best.

Forgive a foolish question, but what's the purpose of the vent? Doesn't the can need vacuum to operate?

[puppet]

Couple ways to look at venting a block. Vent it to atmosphere or pull it out with intake vac or exhaust pulse. In either case, the can catches the gasses and oil mist.

I personally don't like cycling that back into the engine from a performance stand point. So for me, an intake vacuum draw is not my cup of tea. He'd also have to route a line to the turbo inlet for "on boost" vac draw in addition to his PVC hook-up. .. or just vent his can if he didn't want to soil up the turbo.

The other option, using exhaust pulse, involves welding a tube into the down pipe and adding in a check valve. Works really well in higher rpm ranges when exhaust velocity is high ... and the exhaust system is free and clear of mufflers/CATs. Moderate success, as far as vac draw, if off boost with other obstructions in place.

Venting to atmosphere is pretty fool proof and gets the job done, provided the lines used as an exit from the block and/or VC are large enough (when using a catch can) and the exit to atmosphere from the catch can is too. The puke tank will "work" either way.

[turbovanman²]

You need to vent the catch can or the air has nowhere to go, so you'll end up with oil leaks and blowing seals. As puppet said, you can vent to the exhaust but then you can have blue smoke at certain times or if you have lots of blowby. If you just vent it, put a filter on it if its under the hood, it will stink and you will smell it,