Exhaust slashcut PCV System

[Noddle]

Hi,

 

I've been doing some research into this, and I'm after some information on the piece that fits into the exhaust stream, mostly what shape the end is and how far it fits into the exhaust tube and the angle it's attached.

 

I assume it would be best to have it 6 inches or so down from the O2 sensor, and use a catch can with it.

 

Also,with the catch can, should it have it's own breather, so it doesn't create to much vacuum on the engine, see pic1 and 2,

 

something I'm not sure about, should the system allow clean air into the valve cover, and suck it out the engine block vent (to create a passage for circulation), or suck it from both ends (creating a vacuum in the engine).

 

Nigel

[burninator]

I've heard of old school drag racers doing this. I've never tried it myself but I'm very interested in it. The theory is you can make more power by creating some vacuum in the crank case. It will reduce windage and parasitic drag on the crank. And you'll also get some benefit from not getting oily dirty air sucked into your engine.

 

I can offer the following advice from what I've read:

 

I don't think the angle of the cut is super important but I'd do about a 30 degree cut. 6" from your O2 sensor is probly good, if the fumes from the crank case get to the sensor it may ruin the sensor and will likely give you incorrect readings. Do you have a cat? The exhaust needs to flow pretty fast to create any kind of a venturi effect.

 

The catch can would be good if you want to keep the oil from burning once it hits your exhaust but I don't think you'd want a breather on it or you won't get any vacuum.

 

Whether or not you should let air into the valve cover is a little more tricky, you may need a way to control the flow of air into the crank case so it would be good if you could hook up a breather with some kind of a valve that would let you adjust it. Ideally you should shoot for about 13 inHg of vacuum. You should get a vacuum gauge so you know if your pulling vacuum and how much.

 

I was a little hesitant to post anything because I haven't tried it myself, so keep researching. It has been done before, but I dunno if it's worth the trouble or not.

 

Good luck if you decide to try it. Post back and let us know if it works well or not.