Question for those GS 300 engine swap enthusiast. Has anyone installed a Oil Catch Can Kit With Top Filter?
Trying to determine if this is needed if so what brand have you installed?

 

When you say top filter, are you referring to a filter on the catch-can itself? If so I assume it's more of an open loop system you're thinking about where vacuum is not utilized in the crankcase?

I too have been thinking about a catch can solution (or not) for my future as I'm going single and don't intend to use the MAF. Therefore I wasn't going to have any intake piping ahead of the turbo. But after reading an hour+ worth of threads on catch-can's, I'm kind of on the fence. I think they make sense and the science seems pretty sound. But at the same time, I'm wondering if a little open air filter with small reservoir would be adequate on the turbo/exhaust side valve cover. Essentially the crankcase would have vacuum whenever the car was near idle / low throttle but not when under load / boost in that scenario.

 

I chose to run a catch can with my setup. One without a filter on top. That would be for venting to atmosphere. This makes an oily mess and smells bad. I plumbed the lines out of the two cam covers to the inlet of the catch can, and the outlet from the can to the inlet pipe before the turbo (between the filter and turbo). This way under normal conditions, the gasses can make their way out (although not under vacuum) but under boost can still vent, which is important, because obviously under boost there are more gasses being shoved into the crankcase (pressure) and on a stock system it has no where to go because of the PCV check valve. This would blow out seals. By plumbing in before the turbo, you get the suction from the turbo when you go into boost to actually help suck the crankcase vapors through the can and into the intake where it gets burned and keep the crankcase safe from creating to much pressure.

Ideally the basic vacuum assisted setup like OEM is Ideal. But under boost, this system doesn't work at all. The lesser of the two evils is to ditch the vacuum assist and allow it to vent naturally through the can and into the intake so as not to be a polluting a-hole, and to have the best possible pressure relief under boost from the suction of the turbo.

 

So I'm far from an expert of PCV systems, so I'm just trying to solidify my understanding a bit. You say that under boost the vacuum assisted system doesn't work at all. I'm curious about the differences between the GTE and GE PCV system. I wouldn't think they would be very different, although with the turbo, the vacuum provided on the exhaust side should be greater than is available on a non-boosted solution. With that said, I'm curious about why you state that under boost the system doesn't work? Under boost vacuum is given by the turbo-side of the closed system, and when at idle and near-idle conditions, a vacuum is maintained in the intake manifold, which would be the vacuum for non-boosted intervals. And in your scenario, why did you decide to not utilize the vacuum source of the intake manifold as I assume it was in stock form? If I understand correctly, you routed the left (intake) side over to your catch can.

 

I don't know how the GTE works, but on the GE engine vacuum (negative pressure) sucks the vapors into the intake through the pcv valve. Under boost there is positive pressure meaning that it would force the valve closed rendering the system unable to work. And if the valve wasn't there, it would force boost pressure into the crank case (bad thing). So the best option I found was to take both the left and right pcv hoses T'd together and going to the catch can. From there to the inlet before the turbo. So the crank case has the turbo pulling the vapors out. There might be other ways, but this is how most do it and it does a good job of not allowing oil and pollutants out into the engine bay and atmosphere.

 

So just curious - did you route the intake side hose over to the catch can to avoid oil in your intake?

Because during intake vacuum you will be missing out on vacuum in the crankcase without this connection maintained.

 

I think I see what you're saying. If you still want to run engine vacuum under normal conditions then yes, you will need to retain the drivers side pcv outlet/valve and run a separate can for just that side. Then on the passengers side you will want another can between the pcv port and turbo inlet. So under normal running conditions, it will pass through like normal, but under boost it will close the valve from the intake and crank case gasses will have to be sucked from the turbo side. However this still doesn't work like oem. Because the oem setup has free flow from the air intake tube all the way through the engine and into the intake. When under boost, the valve would close meaning there isn't "free flow" just what can make its way out. This isn't too big a deal as people vent to atmosphere with no suction help commonly. But I'm against that. So my way was just to run both pcv holes to a T and to the can, and from the can to the turbo inlet. At least all the gasses that do emit will be burned up and the turbo suction does help to pull gasses out of the engine. Not as good as engine vacuum, but I think its alright.

 

Here, I found this link. Good quick read to help understand why I did it the way I did. The key here is that there is basically vacuum occurring just before the turbo, as the article states, because of the spinning of the impeller. Therefore I didn't see the need for two catch cans, or anything too special. The best we can do really is just allow the turbo to create an area of low pressure to suck the gasses through, and to have those gases go through a can before going to the turbo inlet.

https://www.knowyourparts.com/techni...d-applictions/

 

Consider too, the engine makes vacuum at idle and low amounts of load. This is when the blow-by is at a minimum and least amount of crankcase pressure is created (in a normal healthy running engine). So the need to retain the vacuum source isn't that big of a priority in my opinion. It's under boost that the blow-by will be substantially greater and engine vacuum will not help this out in any way. That is why it's up to the turbo to suck the gasses out. Luckily, the more boost, the more it pulls. So the protection from crankcase pressures goes up along with the speed of the turbo impeller.

 

I follow and in general am in agreement with your approach. I was just curious about your thinking behind your design. I'm pretty sure I want to have vacuum on both sides, if I can. I've run for thousands of miles without a catch can on the intake manifold side of the head, yet the oil in the intercooler indicates a catch can would be helpful. I might see if I can work one in there. I'm 95% sure I'm going to find a spot for one on the turbo / exhaust side. Just need to work out my plumbing and placement options.

 

I'm not sure I understand the exhaust side idea you've mentioned. If anything the exhaust side creates pressure too. Like back pressure in an exhaust system. It would push back. I mean possibly somewhere down the exhaust you might find a way for a siphon effect running past a line plumbed in. But I don't think it would work well. Besides, if you use a good catch can, there should be no way for oil to enter the intake and get into your intercooler. If you are getting oil in there and you are using a catch can, you probably have some leakage from inside the turbo. As I've mentioned on my setup, both lines go into the catch can, then to the turbo inlet. No oil can get past the can.

 

I'm probably creating that confusion. I'm referring to the exhaust side of the valve cover, not actually running the vent to the exhaust system. Which is to say - ideally I'd like to have a vacuum source on that side - which is most feasible with a draw from the intake ahead of the turbo as you have done - with a catch can in between. I have heard of people utilizing the exhaust as a vacuum source. But that seems environmentally irresponsible, in addition to being more difficult and dangerous to do.