S2000 Oil Catch Can
By Rob Robinette
The AP1 S2000 has a habit of spitting big blue oil clouds while on the track in extended right hand corners. An oil catch can will solve the problem and keep you from scaring the crap out of people behind you in fast sweepers. The S2000 valve cover has a baffle (see pic below) that traps oil near the PCV (positive crankcase ventilation) valve. The PCV valve allows the intake to suck blow-by gasses out of the valve cover. It also seems the higher the oil level on the dipstick the more likely you'll burn oil through the PCV valve.
When the throttle butterfly closes during a high RPM shift (or throttle feather) a great amount of vacuum is created in the manifold. This vacuum sucks air from the valve cover's front large vent into the valve cover. This air along with blow-by gasses and oil are sucked across the valve cover baffle, out the PCV valve and into the manifold. The engine burns the oil and produces blue smoke. By placing a catch can in the PCV valve hose you can trap oil and keep it out of the intake.
AP1 Valve Cover Baffle Showing Location of PCV Valve and Front Vent Line
There are two vacuum lines that can be tapped for a catch can. The most common is the PCV valve line. This line is the cause of most "blue smoke" problems. The other location is the large line that runs from the front of the valve cover to the intake. If you're not concerned about keeping emissions legal the best solution is to cap the PCV valve and put a catch can in the large hose. This is what I did to my S2000 race car. The PCV valve uses 5/16 inch inside diameter hose and the large front vacuum line is 1/2 inch inside diameter. I sourced the vacuum hose and caps at Autozone.
A very simple solution to on-track oil smoke is to simply clamp the PCV valve line shut using a large clamp style paper clip while running on track. Unclip the line before the drive home.
For my emissions legal catch can I sourced most of it from Home Depot. It consists of a small (too small, see Update 3 below) compressed air water separator (air tool section of the store), two 90 degree elbows with 3/8 inch hose barbs on one end and male 1/4inch NPT thread on the other (plumbing section), and some plastic hose.
Update: The plastic hose pictured ended up collapsing under vacuum so I upgraded to two 18 inch long pieces of 5/16 inch fuel injection hose sourced from any auto parts store.
Update2: A collapsing PCV valve line is actually a good thing. Under normal driving conditions the hose does not collapse and the PCV valve works as intended but during high RPM shifts when vacuum through the line is very high the lines collapse and keep oil from being sucked through the line. It's a poor man's "active" PVC valve system.
Update 3: The catch can pictured was too small and oil was simply blowing right through the tank. I have seen the next size up air/water separation tank installed in the same location and it works well. Matt would catch about a 1/4 of a quart every track session or two.
Small Catch Can in PCV Valve Line
I used 5/16 inch hose but you can just pop out the PCV valve and take it to the auto parts and hardware store so you can get the right size hose and 90 degree elbows. The elbows are 3/8 inch barbed on one end for the hose, and 1/4 inch NPT thread on the other. The water separator has a valve on the bottom to empty the trapped oil. You can unscrew the glass part of the separator and drain it back into the engine. The length of hose and mounting position are not critical but if you have a shock tower bar mounting it there works well. I have seen catch cans mounted on the stock air box too, but you'll need about 21 inch long lines to make that work. If you remove the cruise control actuator a catch can will fit there too.
Racing Catch Can V2.0 (not emissions legal)
PCV Valve Line Removed, Catch Can in Large Vent Line
This is my current setup. I completely removed the PCV Valve vacuum hose and capped both ends. I connected a Greddy catch can to the valve cover's large (1/2 inch inside diameter) front vent line. I placed a breather filter on the catch can's outlet and capped the input on the intake. I could have run a line from the catch can to the input on the intake (before the throttle butterfly) but a breather filter keeps things simpler.