The V8 Owners Forum -

I know there have been recent posts regarding Crankcase breather options but I have a specific question. Just got my 4.3 running with a Rotrex, intercooled, MS3 without AFM and have just vented the rocker breather via a filter in the Bay.
Fumes at Idle make my eyes water and since this is a road car I thought for simplicity I could connect the breather directly to my 32mm recirculation pipe which returns to the intake of the blower.
It doesn't appear to have sent oil out of the filter so far (about 80mls of testing, approx 12psi boost) so I assume that not too much oil would find its way back into the system however I guess the recirculation pipe at some point is pressurized slightly when idling or coming off the throttle?
Would this be a problem, wasn't intending to have a flame trap or catch can though if possible?

So those oily fumes that makes your eyes water in cabin... wont find their way to much into the system.....

Id say throw your intentions overboard... flame trap ( always ) and catch can routed in the PCV system.

O.K better order some bits
Is the flametrap more important on a boosted engine,didn't have one before?

After searching flametrap I see the rocker cover did have one fitted as standard so just need the catch tank. Options seem to start at 0.5l to 2L capacity, space is tight so prefer the smaller but typically in normal driving how long until this would need emptying?
Don't have a return to the sump

Well you don't want to drain it into the sump as it has moisture in it.
The bigger the catch can the more space it has to condensate leaving less contaminated air routed back into the intake.

Some catch cans have a sight tube others don't.
As the oil vapour condenses to the bottom of the catch can you just have to check it once in a while. In normal situations you don't have to worry much about it. Just don't wait till its full.

Just route the catch can between your flame trap ( valve cover) and PCV system ( intake somewhere ) so its a closed system.

The issue with a boosted engine is more blow by on the pistonrings and while under boost oily fumes can cause detonation as it lowers the octane of the fuel mixture.

A good working PCV system saves you from those eye watering fumes and will save horsepower as it lowers bottom end pressure below the pistons.

Thanks, I'll try and make some space!

As long as it's not illegal over here, I'd recommend something like this:

http://www.summitracing.com/int/parts/sum-120108

Keeps the vapours out of your intake and also pulls a vacuum on your crankcase.