Once we broke up in the IRC room for the night, I figured that I owed it to myself to see if there really was any truth in the matter of the breather filters. Bruce had pointed me to one of the most elite sites on the net when it comes to engine flow and dynamics, www.theoldone.com. ENDYN (Energy Dynamics) is a site that's comprised of several top-notch import engine builders in the world and is even sponsored by a person that's from Taiwan. Needless to say, the information submitted to me was 100% on the money.
Here's how the intake system works. First of all, the only way that the case will get fresh air is if you put it in there. This is why the stock setup has the line that runs from the valve cover to the intake tube which sits directly in front of the throttle body. By removing this and replacing the line which starts at the valve cover with a Breather Filter, you basically knock off the importaince of the air flow into the case. Unlike popular belief, the case doesn't suck in its own air while running. The reason this is dangerous is because of the PCV valve system. While the engine is running, dangerous and extremely hot gases build up inside the valve cover and they have to be extracted; this is the sole job of the PCV valve.
T.O.O. on the subject of
crank case ventalation. Here you'll read about the way a system should and should not be
setup. Inside the link you'll read a few times on what they basically call a "slashed
hose". Below is an awesome pic that's been hand drawn on a sheet of paper and scaned into a .jpg format for people like you and I to view.
T.O.O. claims that he knows people that have actually had to re-build an engine due to the case breather filter. Under serious conditions such as a Supercharged/Turbo/NOS setup, and mathmatically speaking, the valve cover is likely to blow off the head! The case has to have a positive pressure coming in from the intake tube, and will exhale with a negative pressure while releasing the gases and build up from under the cover. Positive intake pressure can't be obtained with the case breather filters. Always remember that the car/engine will last only as long as you take care of it. Just as you change your oil in order to lubricate and prolong engine life, I firmly believe that this mod will also help to extend engine life. Do cars run w/o this intake mod? Of corse they do. Is it going to make or break your engines performance? The only true answer is, only time will tell.
The newer designed intake system will increase the head ventalation systems efficiency. Fact of the matter is, this is a great little trick that should be common knowledge to everyone. If you perform this work, I'd like to hear from you and see what your impressions are from the mod. I'm willing to post a response to this article if you'll take the time to send in a follow-up.