1996 850 boost pressure into crankcase/ one way valve.

[tardcart]

I don't think bigger hoses would help, the constriction is the PTC. and I see Volvo carefully insulated the hoses to keep them hot so
its good to keep the stock ones. a catch can would be a point of condensation since cold, and probably should be under the intake which is not convenient, to limit long cold hoses. but I don't see the benefit to collecting instead of burning off the moisture and vapor. unless
you are racing and are required to. So that leaves finding more vacuum like a reservoir or providing a high pressure shunt around the PTC only when needed. (all the time under boost really) plus a back check vacuum valve to keep the boost out of the circuit. The crankcase pressure is high pressure low volume so would not throw off the maf considering the air flow of 2.3 liters at 5000 rpm.

[Sommerfeldt]

I don't think bigger hoses would help, the constriction is the PTC. and I see Volvo carefully insulated the hoses to keep them hot so
its good to keep the stock ones. a catch can would be a point of condensation since cold, and probably should be under the intake which is not convenient, to limit long cold hoses. but I don't see the benefit to collecting instead of burning off the moisture and vapor. unless
you are racing and are required to. So that leaves finding more vacuum like a reservoir or providing a high pressure shunt around the PTC only when needed. (all the time under boost really) plus a back check vacuum valve to keep the boost out of the circuit. The crankcase pressure is high pressure low volume so would not throw off the maf considering the air flow of 2.3 liters at 5000 rpm.

The whole point of a catch can IS to be a point of condensation, so keeping it warm would negate quite a bit of its function. The crankcase doesn't just puff out air, you know - there is a lot of things in there that will hurt both your power numbers and your engine, building up deposits of carbon and polluting the intake air, wearing on the turbo and clogging intercooler space.

Considering the relatively free flowing passages, the crank case both should not and would not be a high pressure environment - that's what the PCV system is there to prevent. The Volvo system is always open, so more free flow and larger hoses can do nothing to hurt it.

Not sure what you mean by considering the airflow is 2.3 liters at 5000 rpm - if you're running boost, the engine is effectively larger by a factor of the boost pressure, the engine will move that air very quickly. Also, air mass is measured in kilograms. Take a look at the MAF limits for these engines, and be aware that they can max the MAF capacity.

- S