Crankcase Vent Tank
In 2009 the One Lap VR-4 struggled with crank case pressure and oil control. We were using the stock 3/8″ fitting off the valve cover feeding to a .75 quart catch can. The stock PCV system was retained with a new PCV valve. We found that after a 4 minute hot lapping session the catch can would fill and blow oil out of the filter all over the engine bay. That meant that we not only risked getting DQ’d for leaking oil but we were at serious risk of a fire. Hot oil has this uncanny way of bursting into flames when you least expect it.
At the top of our to do list for 2010 was to design and build a better system. We took a lot of advice from the NABR and Galant VR-4 guys and this is what we came up with. Its basically a welded aluminum tank with two 8 AN feed lines from the valve cover. It has a 12 AN port which will connect to the pre-turbo intake pipe to provide a source of vacuum to the tank. The really cool feature is a 6 AN drain port on the bottom which will allow the oil to flow back out of the tank and back into the block via the rear balance shaft inspection hole. We can do this because we have removed the balance shafts from the motor. Finally, the tank measures 3.75 quarts in volume so we should have lots of capacity and no hot oil flying around under the hood.
I started with section of 4″ extruded aluminum tube that I had left over from building intake manifolds. The plan is to mount the tank along side the fuse box that sits in front of the passenger side wheel well along the fender. That will give a strait shot from the valve cover and should be close enough to the intake to make connecting it a snap. To cut the stock I am using a table saw with carbide blade. Sounds dangerous but the blade is designed to cut metal and except for the flying bits of aluminum its no worse then cutting wood.
Instead of weld AN fittings I am using the cheapest hose ends I can find and then modifying them to fit. The real head scratcher for me was how to design the inside of the tank. What I did was to kind of box off the two 8 AN inlets so they would blow against a wall. That way the oil could just run off the wall into the sump. I also boxed off the 12 AN vacuum port so even if oil was flying around inside the tank there would be no way for it to get to it. Finally I decided to wedge some scotch-brite pads between the vacuum box and the tank. I am hoping that the surface area of the pads will allow oil vapor to condense and drain out before it gets to the intake pipe. Honestly, I just don’t know how its going to work until its on the car and we are half-way across the Nation.
On the valve cover I used the existing vent port. I knocked the stock steel tube by clamping it with a vice grip and then whacking the vice grips with a hammer until it came out. I then drilled out the hole to 5/8″ (8 AN) and welded it all up. The second port was mounted right next to it but I was forced to install it at a slight angle to allow it to clear the thermostat housing. To get the stock baffle out I drilled out the little nubs and pulled it out. I made an attempt to reinstall it but my welding skills aren’t that great and I just ended up blowing holes in the thin aluminum baffle. So I made my own out of some 1/8″ sheet. I traced the outline using the old baffle and then welded two tabs to keep oil form getting in from the top. Its not pretty but it covers to ports and thats all I needed it to do.
Its not totally finished yet. I still have to make the lines, install the tank under the hood, and make the connection to the BS inspection port. I will update this when its all in and tested.
…as promised I have some updated photos which show the tank installed. I wanted it to fit tighter to the fuse box but the two wire looms would not move enough to let it fit. So it sits an inch or so closer to the valve cover then I wanted but I still think it fits well. For now, I’ve also decided to cap off the PCV system. I may or may not bring it back depending how the tank works without it.
Hi there, just doing some research for my Yokohama site. Amazing the amount of information on the web. Wasn’t what I was looking for, but good site. Have a good day.