realblag

You don't need the vacuum. The only reason factory does it this way is for emissions. Allowing the case pressure to vent itself to atmosphere through a catch can works just fine.

Slowcrash_101

I'll just say that you don't gain anything by venting vs using the system as it was intended whatsoever. If it ain't broke don't fix it.

SouthDakotaS2K

Positive pressure in the crankcase can lead to significant issues if not corrected. If you have enough pressure to push out the dipstick you also have enough pressure to push out a rear main seal, a valve cover gasket or even force oil out the fresh air inlet. The idea of an aftermarket catch can or open breather system is to vent excess pressure created by an engine that is creating an excess of positive pressure that exceeds the capability of the stock system. This is most commonly found on forced induction engines where the cylinder pressure is abnormally high, but can also be found on high compression and also worn out engines. The factory system is generally good with a fresh air inlet in the front of the valve cover that allows filtered air from the intake tube to enter the valve cover, and a PCV system which allows the vapor to be removed from the engine under certain load conditions. If the pressure spikes during acceleration for example the pressurized crank case vapor can back-flow from the valve cover to the intake tube via the unrestricted hose in the front of the valve cover. Once the pressure is normalized the flow can reverse to the PCV to cycle out crankcase vapor keeping the engine cleaner and more dry inside. A race style vent kit does not circulate the vapor like the stock system and subsequently the oil must be changed more frequently.

SouthDakotaS2K

I should also mention that on some applications like the s2000 that have a tendency to use a bit of oil through the vent system a oil separator box can be used to help filter out the pesky oil droplets that lead to the annoying engine smoke. I have also seen guys run the race breather kits with a secondary air injection pump in the system to help circulate the crank case.

davidc1

Confused....You say leave it connected, presumably so the manifold provides the vacuum, but they you say hook up and catch can and let it drain into the sump...meaning it's not connected to the intake manifold, correct?

vtec9

For me, the pressure leaked out the spark plug tube seals, and made the chicken cluck noise. I did not have enough pressure to pop out the dipstick, but I've since restored the system to stock.

AP1Driver

There is no harm in removing the PCV system entirely as long as the VC is vented properly. Those "vapors" build up a nasty oil residue on the TB butterfly, in the intake manifold, and on top of the pistons. You will also experience reduced oil consumption as there is oil is no longer being sucked into the manifold from the PCV. I've been running this setup for 60k+ miles and have had zero issues.

Slowcrash_101

What I meant is that the ideal system is still connected to the intake. The difference is that the hoses from the breather and pcv go to a catch can, then hoses from the catch can go into the intake manifold.

Ideally again, this system would work as it was designed, and would give you a way to accumulate the oil that comes out the breather and PCV. Sort of like version 1 here http://robrobinette.com/S2000CatchCan.htm

The only difference is that the breather would also run through this system, and you would have a way for the accumulated oil to return to the sump, but that requires engineering.

SpitfireS

As far as I understand the main reason for a PCV valve (= a check valve = 1-way valve) is to make sure no pressure is going from the intake manifold into the crank case.
The intake is a source of vacuum (under certain conditions - as mentioned) to help to remove pressure build-up from the crank case.


What is the benefit of sealing the intake from any other flow into it than coming from the air filter?
Power?

Slowcrash_101

We're talking in the order of a fraction of a horsepower, so if you would rather make 203.46 to the wheels as opposed to 203.45 by all means.