Crankcase ventilation with a Supercharger. What should I do?

[BlackFox5.0]

First. I don't like the idea of putting any hoses from the valve cover or pcv in front of the blower for vacuum because I don't want oil all inside my supercharger, and up into the bypass.

I was told I should take the vacuum line off the PCV valve, and to cap the line from the TB to the valve cover, which I already did.

Why should I touch the PCV? It's a one way valve, so when I make boost, air is not able to go in and pressureize the crankcase, right?

I was told I should definately run a breather, I told a friend of mine who recomended that I use one and showed me a breather that screws in where the oil cap is, so I told him I heard a breather would let in unmetered air into the engine, and he said how? and that it would not.

So what do I do about the whole pcv system, and should I have a breather?

 

[Mustang5L5]

I was told I should definately run a breather, I told a friend of mine who recomended that I use one and showed me a breather that screws in where the oil cap is, so I told him I heard a breather would let in unmetered air into the engine, and he said how? and that it would not.

I dunno if i said this when i talked to you, but when they say unmetered air into the engine, they mean into the throttle body and intake and not inside the actual engine itself. If you run a breather you cannot still run the tube going from the VC to the TB because air will be drawn in or blown out the breather under boost. WHen you cap the line, the air goes inside the engine. Now all the air going through the MAF is going into the engine.

The same goes for the PCV. Now the air going through the PCV is drawn through the breather and into the intake eventually. Unmetered air. So neew to put a breather there too.

 

[BlackFox5.0]

Ok, I see how unmetered ir can enter a n/a engine. I thought it would suck in air from within the crankcase somehow, lol I didn't really put that much thought into it.

So on a n/a car the crankcase is vented by vacuum, and on a s/c car the crankcase is vented by a breather, right?

What do I do about my PCV valve? A friend told me I should gut the PCV or something and leave it in there I read another post about someone plugging the hole, but then having only one breather won't really help with venting...

 

[BlackFox5.0]

ttt

 

[Rick 91GT]

Leave the PCV valve functional as it was stock you need it, if you have a A-Trim kit it comes with with a hose with a inline filter that goes to the filter box from the valve cover, or cap off the nipple at the TB and valve cover and run a open element on the valve cover.

 

[BlackFox5.0]

If I leave the PCV as it is, and put a breather, then I should suck in unmetered air from the breather through the PCV right?

I don't have the stock vortech airbox, I have a power pipe, which I don't want to drill and put the PCV or the line from the valve cover like I have seen a few people do, into the inlet of the supercharger. My engine likes to suck oil from the valve cover into the TB, which I don't want all inside the blower and tubing...

 

[Michael Yount]

If the pcv is left hooked up, and the throttle body/valve cover lines are capped, then you will pull in unmetered air whenever you have a vacuum in the intake. Not sure how much of a problem that is however. I'd try that first - cap t/b and valve cover nipples; leave pcv hooked up (will it withstand your boost pressure? Some have mentioned using Thunderbird SC pcv for that reason); put a breather on the valve cover. If you don't want the mess that a valve cover breather often makes (oil mist over engine), then you could run the valve cover vent to a plastic catch can (speed shops sell 'em) and then run the other catch can line to the inlet piping of the supercharger. THe catch can should catch any excess oil keeping it out of the inlet piping. Definitely don't do away with the pcv without venting the crankcase - crankcase pressure will blow oil past seals. Lastly, you said "Ok, I see how unmetered ir can enter a n/a engine. I thought it would suck in air from within the crankcase somehow, lol I didn't really put that much thought into it." That's exactly how the unmetered air enters. Normally that make up air would be provided by the little hose that runs from the throttle body to the valve cover - after it's been metered by the maf. But when you block those nipples off to keep from pressurizing the crankcase with boosted air, you eliminate a metered source of make up air for the engine.

 

[Ranchero5.0]

Blackfox, you have some blowby. Leave the PCV hooked up and do like Micheal says with the bottle and a hose if it's too bad. When I first got my '93 I was blowing a quart of oil out the breather every 150 miles. I ended up routing a line from the valve cover to a windsheild washer bottle from my '69 stang. I drilled the top and put my stock PVC into it and it worked pretty good as an oil / air seperator. Knew the bottle was full when oil started streaking up between the fender and hood. Sucked, but it was a 75 mile trip to work each way each day and I had to deal with it for two months until I could redo the bottom end. Found two pistons with cracked and blown out lands and three intact oil rings. The rest were broken up from running 87 octane with a blower on '93 hyper psitons...

Jamie

 

[BlackFox5.0]

I hear a lot about using a Turbocoupe PCV, i have no idea how it's used though. I don't think I have any blow by right now. I'm only putting out 6 psi.