SPOHN'S Journal II Track Demon Reborn

Red__Zed

With FI it's probably smarter to eliminate it than to leave it. You're looking at a very different engine ecosystem with boost.

Sh0velMan

I don't see how.

Every factory FI car I've owned had it, worked fine. Difference all of those systems are draw-through rather than blow-through.

As Syno has pointed out, the valve closes so as not to allow pressure into the crankcase. Under boost, no evacuation occurs, this is normal. Off boost, the system works as previously. We're talking about 8-9 PSI at most on the stock bottom end, so the boost pressure isn't likely to destroy the PCV valve.

I can see how you'd pretty much have to run breather filters though, otherwise the inlet ends up being on the cold pipe (and thus pressurized) since we run blow-through FI on these cars. I can tell you from testing that the car will adjust the idle air bypass to adjust for what is essentially a vacuum leak if you run the PCV vacuum without having it plumbed to the intake tube.

With proper tuning, it could probably be made to work fine, so that's my suggestion:

Breather on inlet, outlet to manifold, drivability tuning to account for the more or less static rate of flow through the PCV system off boost. Static meaning the orifice is always the same size, so you can adjust for it easily. You'll get the good evacuation without the risk of boost pressure causing issues in the crankcase. Win/win.

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