I've seen many setups with big HP and still running the PCV to the intake manifold

Just vent to atmosphere, or if you still want to pull vacuum, then run it thru a baffled catch can and then to the turbo inlet (between air filter and turbo) - That'll pull some vacuum under boost and the catch can should hopefully trap all the gunk.

 

So does this mean turbo back pressure has nothing at all to do with crankcase pressure?

 

I dont think it will effect your tune. Although, you wont be pulling anymore oil fumes into the intake and burning it anymore so it may effect the normal out of boost driveability but I doubt it. Check with your tuner and see what he says.

 

Thats a tricky question to answer.

I would say typically no. If you are referring to turbine back pressure, that is going to limit your overall whp I'd think.

While the more "power" you make, the greater your crankcase pressure could be, assuming you don't have the proper gear in place to keep it balanced.

However, if you had a poorly setup system, i.e. your turbine housing was to small for your setup, downpipe to restrictive, and even the wrong cams, you could start to see reversion in the cylinder which could cause excessive crankcase pressure as well.

So I guess it's a yes/no answer, lol.

If you have EXCESSIVE pressure, I'd check the cylinders themselves for leakdown first. If that passes, then look into proper venting.

 

Ideally, I prefer to keep a PCV system on the car- pulling vacuum at idle and decel on the crank case can help a lot with turbos smoking under those two conditions.

I would vent the breather port to atmosphere, and add one or two additional vents on the valve cover depending on your setup. That should allow sufficient venting under WOT conditions when the PCV is closed.

 

What exactly are you referring to?
Do you mean "backpressure" on the turbine (header/turbo/downpipe/exhaust) or do you mean "backpressure" on the compressor (turbo/charge pipes/intercooler/intake manifold)?

As stated by Siadam, the more boost you run, the more potential for the crankcase to become pressurized. Cylinder pressure leaks through the pistons into the crankcase and pistons have to work against the crankcase pressure as they go through the stroke cycles, decreasing power output. That's why venting the crankcase to atmosphere or pulling vacuum is desirable in boosted engines.

If you meant backpressure on the turbine, then that's another matter. I believe that would be resistance to exhaust flow. If it takes a certain amount of pressure to exhaust a certain amount of gases from the engine, then that's "backpressure" and it also reduces the amount of power the engine can make.