Cam cover breather modification.
I did some modifications to the cam cover breather channeling on the hot side of the cover based on some theories from mt.net and ms.net. I bored out the “slurpee” channel between the inner and outher chambers with a 10mm drill bit as shown on the pictures for better flow. The rest of the breather setup is stock complete with the MSM catch can and oil return on the cold side of the block except I vent the pipe that used to go to the pre turbo intake pipe to atmo. I was expecting some oil mess but I havent seen a single drop of oil after the modification. I will do one last modification by connecting the catch can to the exhaust like the Yanks do on the V8’s. This will create a lot of vacume if done right but hopefully not enough to suck oil back up the oil return. Time will show.
Some pics.
Stock valve cover. The covers over the breather channels need to be removed with x screws and carefully pryed of without bending them as they are glued into place with silicone.
The path of flow is into the middle chamber trough the box looking thing and out to the other chanbers.
Here is the hot side chamber with the “slurpee” hole between them
This hole will be submerged in oil and act as a vapor lock for incoming air trough the intake. The hole is about 5 mm. and goes from the top of the inner chamber to the bottom of the outer chamber.
The cover has a little sump to make the vapor lock work:
For some reason I did not take any pics of the modified hole but just picture ramming a 10mm drill trough the orginal.
I did not touch the cold side chamber as the vapor path is very free flowing stock. Only some walls to make the vapor shed some oil before going trough the one way valve into the IM.
As a side note I have only tested this on an N/A engine since my Rotrex has not been put to work yet. I’m confident that enlarging the hole to the hot side chamber is necessary to vent pressure under WOT. Especially when boosted.
Update 2012.04.21: I did a full trackday with a C38 Rotrex @ 1.2 bar yesterday without a trace of oil out of the vent. This mod really works. Evacuator in the exhaust not needed.
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