This crankcase breather is a valve, don’t let the filter fool you, it isn’t sucking anything in. The breather kit has a ball inside it with an O-ring, and it opens to pressure and closes to vacuum.
The filter is only there, to prevent any oil spraying out in your engine bay if any would manage to make it through the baffle system, which has multiple filters, so you won’t be seeing any oil coming out really.
What is it used for?
There is very high pressure in the cylinders above the pistons when the combustion occurs, and increasing engine power also increases these pressures, and some of that pressure, manages to leak past the piston rings, which pressurizes the crankcase.
This breather kit is meant to release those built-up pressures.
There is something you need to be aware of.
You are letting the air out in the engine bay, which is very close to your cowl filters, so you are going to smell fuel and oil vapor on WOT.
I have also noticed that I was making slightly less boost, with the same wgdc.
You can’t forget, that the N54 head has small holes in the intake ports, which go straight to your valve cover, so when you are in boost, you are also pressurizing the crankcase through those ports.
By letting out the pressure from the crankcase, you are also letting a small amount of the boost out. From what I have noticed, I lost around 0.5 psi at around 5500 RPM, where I was targetting 20 psi.
The only solution to this is plugging the head ports, which you can find guides to all over the internet.
I would only really recommend this breather kit if you have the head ports plugged.
