Project AE86: Better Venting

Last track event, I was having serious blow by issues. People were telling me the piston rings might not have been seated in correctly or my head wasn’t sealed correctly. The motor felt strong and fine, but after 3 laps my oil catch can would fill up to the top. No smoke from the exhaust either. I would only get this issue at the track. Street driving, I had no oil in the catch can.


I did a compression test just to make sure it wasn’t something too serious. I got 190 psi on all 4 cylinders! That means my motor is healthy. My motor is creating a lot of crankcase pressure and oil surges. The cause is ventilation issue with the constant high RPM and high g forces at the track.


The 4age came stock with two valve covers. One valve cover wasn’t vented. The other valve cover came with a small 1/4″ fitting that I connected to the catch can, then vented to the atmosphere. This setup wasn’t doing enough to relieve pressure at the track. I had to make the crankcase breathe better and decrease pressure. I did this by adding a 1/2″ barb fitting on each valve cover.


I had my friend Danh come by to weld my barb fittings. The problem was welding aluminum. Apparently, its more difficult to weld aluminum and the welder we had wasn’t equipped for such a task. It wasn’t getting hot enough to melt the aluminum to form a bond.


Danh pointed me to a shop called Prospeed Autosport. They welded my barb fittings, and did a good job too. Kinda expensive, but I can see why. With aluminum you need argon gas and a aluminum welder, which isn’t cheap. Welding aluminum is a lot more trickier then steel.


I went up a significant size from stock. I figured a bigger diameter will help the crankcase breathing and pressure. Its kinda like breathing from a straw. Larger the straw, the easier to breathe and less pressure.


The previous oil catch can was too small. I upgraded to a Cusco oil catch can. The Cusco version has increased capacity, and a visible dipstick. I also routed bigger hoses to the catch can.


Another thing that can be causing increased crankcase pressure at the track are the stock windage tray and eBay baffle pan. The eBay trap doors and stock windage tray isn’t doing a good job with oil surges. I recently bought the MRP racing baffle pan. The part is well baffled with, and has a built in windage tray that is better then he stock unit. eBay parts not cutting and I talked about it in my previous post.


If I didn’t track the car I wouldn’t have to address the issues. Street driving isn’t as stressful on the motor, like it is at the track. Hopefully next track day I’ll have better results and really push the car without filling up the catch can and improve crankcase ventilation.

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