Return or just let out

[mmt 15]

Hi Guys, 

I’m venting a turbo engine. It already has a PCV system comming from the crank case. Original system vents into the intake. 
 

I want to cap the intake port and vent into a catch can breather with a filter on top. 
 

HOWEVER I have been recommended to run a hose from the catch can top back into the intake - track car only. 
 

what is your take do I run the return Line or just vent through the filter? 
 

thanks. 
 

 

[Richie-Van-GTi 71 2 Cars]

Vent it, if it gets messy then pipe it back in.

[petert 586]

The last thing you want is dirty crankcase vapours back into the inlet, if you can avoid it. Just vent to a catch can but keep in mind turbo engines have a lot more blow-by than NA. So you may need to up the sizing etc.

[mmt 15]

Thanks guys. That was also my thinking. 

the suction from the inlet should draw oil vapour to the catch tank without pulling it all the way back into the inlet? 

[petert 586]

The inlet shouldn't be connected to the catch tank at all. Vapours will get pushed into the catch tank without any help from the inlet. It would be different if it were a street registered vehicle. At the race track, nobody cares about emissions. Oil vapours hurt hp.

[mmt 15]

1 hour ago, petert said:

The inlet shouldn't be connected to the catch tank at all. Vapours will get pushed into the catch tank without any help from the inlet. It would be different if it were a street registered vehicle. At the race track, nobody cares about emissions. Oil vapours hurt hp.

Breather it is. Thanks. 
 

additional question: would a one Way valve be a good idea between catch can and engine? Only letting Air into the can and not into the engine. 

[petert 586]

Air (crankcase fumes) is only going into the catch can. It's never moving in reverse, so unnecessary. If scavenging with the exhaust to create vacuum, a one-way valve is added in case of back fire on a NA engine.

Edited April 29 by petert

[mmt 15]

Thanks Peter.