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So, after the track day at Autoclub with my ram air NACA duct, I ran into an issue. This picture shows the typical amount of oil caught in my Saikou Michi oil catch cans during a typical oil change interval with no track time. After the day at Autoclub, the rear can was roughly 2/3rd full! This had to be a result of the ram air duct.So what happened? If you’ll recall from my dual oil catch can setup, the front can goes in the middle of the hose attached in front of the throttle body and the front open vent on the valve cover. Now imagine this, I’m coming off the banking somewhere in the 120mph range and then slowing down for the tight 90 degree left into the infield section. The throttle plate is shut while the car is doing 120mph and the engine is at very high rpms. So now my ram air setup is pushing positive pressure in front of the throttle body and there is massive vacuum in the intake manifold. Well, that positive pressure air has a flow path through the hose on the front oil catch can going into the front vent of the valve cover. Keep in mind there is now massive vacuum in the intake manifold, so the PCV valve is wide open. The second oil catch can is on the PCV line, so my theory is that positive pressure air was pumping through the valve cover and out the PCV valve pushing a lot of oil with it. Good thing for the Saikou Michi oil catch can! Also, recall that I was only seeing about half the theoretical pressure gain from my ram air NACA duct. What was the possible cause? Again, that hose going from before the throttle body to the valve cover was probably allowing my positive pressure air to just flow into the valve cover instead of the intake manifold.
To address the issue, I made a plug for the front hose for whenever I have my track hood installed with my ram air duct. I just got a hose barb union fitting from Home Depot, stuffed it with blue shop towel, and wrapped both ends with electrical tape.
Here is the plug installed ahead of the oil catch can.
For cars like my 2005 AP2 S2000 that still have a good old fashioned throttle cable, remember to tighten it up once in a while as it stretches over time. If you look closely, you can see I tightened up the cable by about 2 screw threads.
To get video of the testing, I used the new Replay XD Prime X. It has many new very useful features over the previous XD 1080 that I had been using on my car, bicycle, and motorcycle. One of the new bits is this angled mount that snaps into the curved base. There are three bases with one being flat and the other two slightly curved (lateral and longitudinal directions) to better attached to curved surfaces like the central storage cover on the S2000.
Another new feature I really like are the graduated marks on the camera body making alignment a snap. For any type of activity where wind noise will be encountered (basically everything but a strict indoor setting), I use the windbreaker sticker over the mic hole.
