When you drill and tap into the valve cover your creating more area for crank pressure to escape through.

The Buschur recirculating catch can is just a catch can. It still has only 2 ports that the same valve cover ports run vacuum lines from.


The best thing to do for power is to run your car without a valve cover. But we cant do that for obvious reasons. So thats why people drill and tap more pcv ports.

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tscomp- try Earl's fuel flapper/check valves. They are $$ but they hold pressure. The other downside is they work better when installed with the flapper hinge up - which means the unit should be parallel to the ground. Might be a fitment issue....

why doesn't anyone vent crank case pressure off the block for high power applications?
Venting off the head means the air needs to come up the oil return galleries, meaning the oil has more trouble returning to the sump?
How about 3x -8AN fittings drilled and tapped into the back of the block (under the intake manifold) that then goes to a sump/chamber then to a catch can?

Thats also a great idea. But more time consuming and difficult to do. You cant really tap into it unless your gonna remove and take apart the block and clean it off etc.... But if your having the block removed and built I totally agree with you.

If you have a built block that cost over 3k i dont know if you would want to take a risk of Fn something up... even a shop{pcfreak}

haha yeah, i meant while it's apart for a rebuild. :)
noone would dare try that with the block in situ!
the only risk i could see with doing it is possible block weakening and a place for it to start to crank. It's thin walled anyways...

I personally would rather find another way than that.. glad Tcomp is testing some ways so when my crankcase pressure rises i have some ideas to run off of..

Buschurs has three, a very large one also at the dipstick. It also acts as the drain back to the block when the crankcase is not pressurized.
Don

https://www.evolutionm.net/forums/ve...ml#post8853606

my first setup will consist of 1 5/8 off the existing side valve cover port going to a sealed can then that can will take another 5/8 or equiv to the air intake. Im going to try the sealed route first, because as is i get no oil in my air intake with no catch can period, so i doubt ill get oil with one.

plus the sealed can will assist in ring seal, and keep vacuum good. turbo does an extremely amazing job at sucking vapors and crankcase pressure out, so im trying this route first.

of course ill update once i get everything all setup and let you guys know how it goes. The can im having made from Saikou Michi is pretty top notch and has all the coalescent filtering and mesh and anything else you can think of to stop oil from getting past it.. far more advanced then moroso cans or most cans on the market. This is what i found after researching into this stuff for the past week.

So i will update once i get everything setup and ready to go. Im having the cans welded or custom modified to utilize a muse anodized black mini battery tray, so it will be a very clean install ( i hope).

Very good thread, tscompusa.

I'm having similar issues (although I am pushing oil and burning it in the turbo). The stock barb on the X valve cover is approx 6AN and that is sounding like a restriction from what I've read here. I bet it'll be a pain to drill that barb off to put another fitting there as well.

My next step is to get a fitting on my intake since I was trying to vta from a sealed can through the small 6AN barb on it. Oops.

Why not just vent to atmosphere as many have done for years?

Not sure what setup you're referring to since quite a few things have been discussed in this thread. If you're using the stock system then disconnecting the intake connection makes it work worse than stock. The combination of the small 5/16" outlet and doing away with the intake suction is a bad combo.

I'm jealous of you 8/9 guys...there are a lot of options for solving this. My X valve cover is shaped such that welding on larger fittings is going to be a pain and the stock outlet is not easily upgraded to 3/8ths like the 8/9 valve cover. {thumbdwn}

That's your best bet. Most people that have dipstick blowing out and crankcase issues are simply because they don't route back to the intake where the vacuum helps in relieving pressure.

Of course there are other reasons, but I think they have all been discussed already (leaky PCV, piston-wall clearance on built motors, etc).

The ports on the stock valve cover is way too small. Much larger lines need to be used. Even -6AN or -8AN is too small IMO. I installed two -10AN lines on mine. Since both ports are in the stock location, it baffles well and doesn't fill up my catch can too quickly. I'd take some pictures if I can ever find my digital camera. If you run a fitting on the non-stock locations it won't be baffled and you will have oil come out.

Before I went with the -10AN lines in the VC, I tried Hals vented oil cap on my last dyno. I gained 10hp! Put the stock oil cap back on and I lost 10hp which means the stock sized VC nipples can't vent enough.

I am running about 630whp uncorrected so stock power they may be okay.

The vented oil cap works great but lots of oil comes out and you need a catch can like Buschurs that drains back into the oil pan if you run it but with a larger -10 fitting. I welded another tube on my dip stick tube and I was considering running another catch can that just drains back for the vented oil cap only. Before I do all that, I was going to dyno with and without Hal's oil cap to see if it makes any difference with the new -10AN lines in the VC.