Yes, but you will most likely ingest oil which you want to avoid. There will be plenty of crankcase pressure under boost to force air out so you don't need to worry about trying to suck it out.

If you hook up a vented can to behind the TB that will be a huge air leak.

 

You can route from the valve cover directly to the exhaust to pull vacuum

 

Would it be a air leak even pre rotors? Like the line goes in the blower snout pre rotors which should pull vacuum which in turn would pull the positive crankcase pressure? It's better to pull vacuum on the PCV vs let it vent on its own right? Like better sealing rings etc....


I've seen this on older vehicles but doubt it would make a difference or do anything on a boosted application.

 

Everything behind the TB is in vacuum at part throttle.

Yea it would pull vacuum on the crankcase, but without a catch can (and even with) you risk pulling oil vapors into the engine. This is a big problem on LS engines in general. For high power builds I always recommend just using a vented catch can or breather tank. Ring sealing is not an issue at part throttle as there is not much cylinder pressure.

 

The below diagram is how I intended to set mine up in order to pull vacuum during part throttle and allow plenty of venting under boost. I ended up just using the vented can after the last time I pulled the compressor off and found the intercooler coated in oil.



IMO other than a variable speed vacuum pump there is no way to pull crankcase vacuum under moderate boost without pulling too much at idle/part throttle.

 

I'm not putting you on blast and please read the following as constructive criticism, not as a negative slaying. What you typed above in red makes absolutely no sense. You make two assumptions:

First you site "old vehicles" as if the year model makes a difference. Physics is physics.

Second, why would a boosted application make it worse? If anything, it could (not necessarily "would") actually make it better. Think about this for a second, the principle works off of exhaust speed to develop a depression in the breather line.....when was the last time an N/A motor had more exhaust speed than a blower motor? Also, the idea of using the exhaust speed to develop the depression works on one simple principle and that is "pressure differential and the venturi effect". Anytime the pressure differential rises, you have more flow. So with the additional pressure in the crankcase specifically as a result of being supercharged......this principle actually responds in a postive way....not negative. This assumes you have the correct check valve in place and the tube in the header facing the correct direction. I'll already correct the come back of the argument that the pressure in the header on a blown deal is very high and could actually pressurize the crank case......check valve and proper tube angle prevents this and creates a venturi effect in the breather line. Due note that the use of a full exhaust system can hinder the effectiveness of this as pressure will back up, but that is what the check valve is for. To the guys with long, restrictive, chambered exhaust systems.....well then, this method may not be right for you.

I'm speaking in terms of a blower deal only now:

I'm of the personal opinion that there is some merit to using the inlet of the blower to create the depression is likely more efficient than exhaust speed. The down fall to this is stated above and that is oil consumption. If the breather lines are hooked directly to the blower inlet, it will likely suck some oil and I DO NOT condone that at all, as sucking oil into the intake can cause detonation issues. However, with the use of a good oil separator and baffled tank (unvented) it just might work pretty good.

I'm a big blower guy and love my prochargers. I actually don't practice any of what I'm preaching above though as I just run big vent lines to vented tanks, so maybe this post shouldn't have been typed, but I'm not deleting now.

Flame on!

 

I was making the assumption that crankcase pressure would be higher on boosted applications and the exhaust vacuum wouldn't be enough to make a difference vs NA. No butt hurt taken. I was trying to think of a way to incorporate a vacuum pump into the front drive and I just don't have the space so I thought the SC could act like one. Maybe using a check valve and adjustable vacuum relief valve so vacuum doesn't exceed 12" or so.

 

Don't think you'll need a vacuum relief of any kind unless you are using a bad *** dry sump pump or a belt driven pump. I'm not sure it would even be possible to pull too much vacuum using the exhaust or the inlet of the blower.

On something that makes a lot of boost (maybe 20 or more is a guess), I could see the ideas we've mentioned above easly overrun if you hurt the motor......and that would cause a bad mess. Like if you burned a piston or something...........it'd blow a ton of oil out the exhaust or into the inlet. That's the primary reason I just run big lines and big tank vented. Matter of fact, if you look at most race cars, the boost guys typically never run a vacuum pump (omit the dry sump guys here) as the vacuum pump alone would get overwhelmed in a hurt motor scenario.

I associate vacuum pumps with the n/a guys doing everything they can to pick up power here and there. They aren't nearly as likely to hurt the motor in a way that would cause issue. These guys are after better oil control and less windage to pick up 10-15 or maybe even slightly more horsepower using vacuum in the crankcase. For the boost guys, we can just add a pound of boost for the extra power and not worry about over complicating ****.

There have been several times I've noticed guys who run the lines to the headers and are efi (capable of logging ****). I almost always pm them or try to ask them if they have data logged proof that the exhaust method works. I've never been satisfied with good answers though.

 

Thoughts on these head gaskets?

ICS Titan Head Gaskets for LS-LSX: S19166 | SCE Gaskets

 

They look really nice!