Obviously I cannot just leave my PCV connected to manifold vacuum, which will shortly become boost.

Should I run a check valve? Or do people somehow replumb it to the intake side of the turbos? I'm not even running filters for the dyno so I don't really have a good place with any suction to speak of...

Can I just leave the crankcase vented to the atmosphere or will the blowby from a boosted engine be too much? I think this motor already suffered from a bit of blowby (though it checks out OK).

 

The PCV essentially is a check valve, though not 100% air tight. But it is good enough to just leave it as is. Check to see if air will go thru to the crankcase side.

Ideally, you want a normal PCV setup on one valve cover running to the IM, and a breather from the other valve cover with hose running to the intake pipe of the turbo (with a catch can in that hose if possible). That is how they do it on factory turbo cars (minus the catch can).

That way, the crankcase will be vented whether you're in vacuum or boost.

Al

 

Thanks! I used to have a 1990 Eagle Talon TSi AWD myself. Not knowing any better, I'd just pull the wastegate line off. Can't believe it survived so many times!

 

Some pcv valves are better than others as well. The turbo 2300 Ford has a decent one iirc, or some use a check valve from a 90's Honda brake booster. If you hook your vent line to your turbo inlet, just make sure to check it for oil residue... It's not uncommon to pull oil, and thats where the catch can comes into play. Many eliminate the pcv on a turbo setup, and just vent the crankcase.

 

most oem ford pcv valves from the 80's 90's work good as a check valve as long as they are the plastic bodied ones. all of the ones you get at the parts houses do not act as a check valve. some engines do not even have a valve at all, like the ls engines their pcv valve is built into the valve cover and is just an orfice.

but in any case something like this works well.
ht tps://www.amazon.com/Farmunion-Return-Petrol-Diesel-Aluminium/dp/B01FSSH7Y0/ref=sr_1_3?s=automotive&ie=UTF8&qid=1488632888&sr=1-3&keywords=check+valve

 

Steel PCV are generally better.. As said a one way valve from JDM brake booster hose does the extra safety check..

 

This alleged brake booster valve needs to come from a factory turbo car, to be sure it will act like a check valve.

I have looked at several brake booster valves in those "HELP" packages at the parts stores, and air will go thru them in both directions.

Al

 

If air goes both ways, then how can they be a check valve?... lol. I've personally had good luck with the Honda check, and a pcv from a 2300 Ford turbo.... but they were oem, not the cheap junk from the parts stores nowadays.

 

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I run a small K&N filter in each valve cover. It hasn't been a problem on any of the 8 turbo cars I've built.

 

It's all about preference as long as it's vented well enough. I've been running catch cans, but there are many good ways of making it work.

 

All I know is a brake booster valve from a 1993-98 Supra Turbo is a true check valve. Can't say what brake booster valves from N/A cars are, as some I have checked will allow air to go thru both ways.

Al

 

I believe you, but if they're not check valves I surely wouldn't want them on my brake booster..... even n/a are designed to run a check as to allow the driver some "reserve" power brakes if the engine vacuum goes away (engine stall or whatever). I'll admit its been awhile since i've looked, but I don't recall ever seeing a vacuum power assist without a check in the system somewhere. That being said, i'm not saying that all will seal against several psi of boost.