MY94BlueWRX

Right guys...

Need some advice on a track car, we have recently set up a Catch Tank (2ltr baffled type, designed myself and had fabricated - see below image) It is vented to atmos and does NOT drain back to the sump, it has both rocker breathers and the crankcase breather routed to it.

We were at Oulton Park yesterday, and after the morning session plus one afternoon outing we had managed to blow out 1ltr of oil!! Now we have done 3 track days prior to this one without the catch tank, and we have never lost this amount of oil ever...

So I can only assume that we have badly designed/installed the catch tank, therefor it's created a pressure buildup/bottleneck...? or that we are getting oil surge round the fast bends (all of them!!) and the crankcase breather is sucking up oil, but why didn't it do this with the original PCV system...?

The outlet breather from the tank is a 19mm ID pipe sleeving down to a 12mm ID pipe 6 inches after the tank, as this was all the pipe I had available at the time, would this cause a problem...?

Cheers in advance.
Kim.

MY94BlueWRX

OK then,

After a bit of thinking and head scratching... the original system wouldn't have lost any oil as the PCV valve would have been closed under boost conditions, this doesn't mean that oil wasn't being blown out of the breather, just that it had nowhere to go as the PCV valve was shut so it naturally drained back into the crankcase.

So a reasonable conclusion would be to drain the catch tank back into the sump, giving the oil a route back into the engine... and/or fit a baffled sump to try and minimise oil surge/blow by.

Does this sound about right...?