PCV solution for turbo m52 swap?

[haaken675]

Hey everyone, trying to wrap up some of the loose ends, and the catch can/pcv solution is next on the list. The big question is, am I better off just routing the valve cover breather directly to a catch can, or should do this but also use the turbo inlet to draw vacuum into the system. This is essentially what the catch can setup on my n54 does (with a proper PCV valve of course). I'm just not sure if i might draw too much vacuum this way.

What is everyone's best suggestions for this scenario? The car is being built for track use so it will be seeing a lot of high RPM under boost.

Thanks!

[moatilliatta]

Mann Hummel makes a nice catch can that catches about everything if you can package it.

Have you though of pulling an venturi into the exhaust?

[haaken675]

Their catch can looks nice, but I still want to better understand the vacuum issue. I'm still unsure if by using the turbo inlet on my car if I will be pulling to much vacuum under boost. The n54 in m 335i is setup this way, but thats also how the moto was designed.

And there is ZERO chance i route this though exhaust, lol. My exhaust is tight enough as is.

[moatilliatta]

Really the amount of vacuum will be determined by how restrictive your air filter is, many cars run a vacuum from the intake side with only the oil vapor management being the biggest effect for years and many of applications.

[the_eskimo_wonder]

There's no real chance you could pull "too much" vacuum through your pre-turbo intake unless your air filter was drastically undersized. Pulling some vacuum on your crankcase improves ring seal and increases horsepower. But in order to hit that level of vacuum you would likely need to implement a mechanical vacuum pump like the big power drag racers use.

This is mostly conjecture as I don't believe I've ever seen back to back dyno numbers with a vent to atmosphere catch can vs pre-turbo inlet catch can but I think if you were really maximizing that ring seal effect, there would be no need for mechanical vacuum pumps.

[Northern]

Mann Hummel makes a nice catch can that catches about everything if you can package it.

Have you though of pulling an venturi into the exhaust?

I ran a Mann Provent 200 for a few months. The way it's built internally is more or less like a larger obd2 CCV, except there's a filter for some reason, but it doesn't filter the air going to the vacuum source

[haaken675]

There's no real chance you could pull "too much" vacuum through your pre-turbo intake unless your air filter was drastically undersized. Pulling some vacuum on your crankcase improves ring seal and increases horsepower. But in order to hit that level of vacuum you would likely need to implement a mechanical vacuum pump like the big power drag racers use.

This is mostly conjecture as I don't believe I've ever seen back to back dyno numbers with a vent to atmosphere catch can vs pre-turbo inlet catch can but I think if you were really maximizing that ring seal effect, there would be no need for mechanical vacuum pumps.

That was my thought, but what do I know, I'm just a layman lol... It is also my understanding that pulling some crankcase vacuum is a good thing for seating the rings and thats primarily why i want to do it right vs just a hose to a vented catch can.

[atmh]

As for the vacuum question: the stock pcv system is attached to the intake plenum, which at idle is pulling a much higher vacuum than the turbo inlet ought to be, also that's at idle so less blow-by, presumably.

A turbo car that draws more vacuum at higher load/rpm seems to be a naturally better setup (an NA car will never pull much more than atmospheric at WOT), and it's how I currently have my car setup. But, having said that, I'm reading this thread precisely because I'm looking for some verification that my system is reasonable, so, take it with a grain of salt.

I don't think pcv systems are wildly complicated, and you could probably just copy what the n54 has and call it a day. That's pretty much the direction I'm leaning. I guess the kicker is that you really want the pcv valve, which I'm pretty sure is integrated into the valve cover on that motor, which makes it pretty hard to just pull and slap on an m20 or m50.