Hey all,

A few weeks ago I was able to get the GTT vacuum side Oil Catch can installed. As some of you may know, the N14 has problems with intake valve carbon buildup due to the direct injected nature of the engine. One of the biggest contributors to this issue is the crankcase ventilation system which draws gasses and oil vapor from the valve cover into the intake manifold to be processed through the engine. Since the N14 still uses a traditional throttle body to meter air into the engine the crankcase ventilation system uses the vacuum that is present in the manifold to draw gases from the valve cover. In the N18 the throttle body system was replaced* by the Valvetronic system which meters air via the intake valves directly. This does away with the vacuum in the intake manifold and, therefore, the vacuum circuit of the crankcase ventilation system. Anyway, on my N14 I wanted to try and prevent this carbon buildup by installing a catch can on the vacuum CV circuit. After some searching I found that there was really only one company producing a bespoke solution for this, GTT in the UK. While their solution is rather pricey they did an excellent job in the design. The can and the fittings are very well made, no re-purposed heater hose here.
*The N18 still has a throttle body but it is only used on startup and warmup. Once warmed up the throttle body opens fully and Valvetronic takes over.

Btw, I know many folks have opted to simply plug the vacuum circuit and rely on the boost side vent only. I personally did not like this option as it changes the fundamental design philosophy of the CV system. While it may not cause any issues, I do not know enough to say that with certainty.

So without further ado, here are some photos of the install. I chose to purchase the additional kit to allow me to mount the can in a different location than where GTT calls for. You can see I placed it where most folks put their boost circuit CC's. I had to fabricate a custom mounting bracket but it wasn't a big deal. You can also see I used a zip-tie to secure the fitting on the valve cover. This is likely not needed but, if you can't tell, I tend to overdo it.



And here is what the can collected in only ~200 miles. I will need to be sure to empty this bad boy pretty often. I will likely do this every time I get gas. btw, this stuff STINKS!!

 

Anyone built their own oil catch can ?

Seems like an awful lot of money for a simple oil catch can. I guess $150 to $350 is cool for those...well, you know.
I see no reason a simple can could not be fashioned from PVC pipe (black !), a divider wall, a coupla caps and fittings. Maybe a batch of steel wool. Either a screw on bottom (if possible) or a pet-**** for draining. Or...use a clear tube body so you could keep an eye on the cans fluid level.

I know from past racing that much of the collected fluid will be water, or better, contaminated...water/oil. So there is no way I'd want the "captured fluid" to drain back into the oil pan like some of the catch can/fluid separators do. That's just dumb to me.

Anyone into doing it...yourself ?

Mike

 

While I agree the GTT catch can is on the more expensive side, in my opinion that cost is mostly justified. You have to consider the design factors for this installation specifically.

Almost all of the other OCC's I have seen are installed on the boost side of the PCV system. This is the port on the L/H (drivers in the US) side of the valve cover. The design considerations for this side of the circuit are very simple and easy to produce a cheap solution for. That circuit will never see pressures above or below ambient pressure since it is plumbed into the intake upstream of the turbo charger compressor wheel. In addition, that circuit is only in use when the pressure in the intake manifold is above ambient (i.e. you are on boost) and the vacuum circuit is not flowing. Since this is normally a small percentage of the time the engine is running it will not see a lot of flow. In addition, since this plumbs into the intake tract so far upstream the entire intake system acts as a large "catch can" which would prevent most of the entrained oil mist from reaching the intake valves. The downside of this is it will crap up the intake tract (specifically the intercooler). Not ideal but would still prevent much of the carbon buildup issue.

The design considerations for the vacuum circuit are much more complex by comparison. This circuit will see the full gamut of pressures from full vacuum to full boost pressure. It also cannot leak as that would result in both a vacuum leak and the associated idle issues along with a boost leak and the associated power loss. That necessitates a much more stringent design for everything added to the circuit including the port adapters, tubing, and the can itself. This is where the GTT unit really impresses me. It was clear to me that GTT spent the time to fully understand the requirements for this and develop a plug and play solution that works well and maintains the integrity of the circuit. The port adapters are custom CNC machined with integral o-rings for sealing and separate retaining pawls on the outside to engage and lock into the ports on both the manifold and valve cover. For the tubing they selected a stiff vinyl that will not collapse under vacuum nor burst under full boost pressure. It is also impervious to the oil/fuel/crud that is running through the circuit. The normal solution of heater hose is not designed for these conditions and risks premature failure in the form of collapse under vacuum, splitting under boost, or oil soak and softening with age. Finally the can itself. While there isn't much here that would be majorly innovative they did a very good job in building it. It is 100% sealed for leaks and the fittings for the tubing are designed to lock in place yet be simple enough to remove to drain the can. The can has a screw in dipstick with o-ring on the top you can use to check the level of fluid inside the can. It also has a screw in plug with o-ring on the bottom for draining. It took me all of 2 minutes to unhook the tubes, remove the can from the mount, drain it, and reinstall. Pretty simple.

And because I am sure someone will accuse me of it, I have absolutely no affiliation with GTT and paid 100% full price for this kit. I am an engineer by trade and training and can appreciate good design is all.

 

It looks like you are catching about the same amount I’m getting from other side. Curiosity here are you seeing any oil in your intake tube are turbo inlet?

 

I haven't taken those off to inspect so I don't know. Like I said, I just wanted to address the issue with the PCV dumping directly into the intake manifold and this did precisely that. I would expect the intake tract has a fair amount of oil residue it in from the ~75,000 miles on the engine at this time. I am not inclined to take it all apart and clean it out though.

 

honestly it’s just one or if you are like me 2 band clamps and boom that tube comes off of turbo and air box, this is meant to be easy has to come off for oil filter change. Its really a curiosity, you and I have friendly gone back and forth in other threads. I’m sure your going to document everything,so as a non engineer that loves to tinker, im following for my own good since I’m blocked on this side.

 

Well I am about 800 miles from my next oil change which I plan to perform myself so I will have opportunity to check out the intake tube then. Again though, I am really not concerned about oil in the intake and intercooler for myself. If I was I would probably have installed a second catch can on the boost circuit. I might even do that at some point in the future if I feel like it.

If I find a lot of sludge or concerning buildup in the intake, I will note it.

 

when I swapped my intercooler out there was oil in it, it was dirty oil, not anything like what I have been catching. Next oil change while on rack, I’m going to pull intercooler tubes and double check and make sure.

 

Geeze...it's just an oil (and actually more of a water) separator. Pretty far from rocket science..!
I've been looking at the different designs the past few days. It seems many aren't that good of a design...in my mind anyway, and over priced. Some are reasonable, and mildly over priced, some are...closer to rocket science in design, but for what they do...are WAY over priced.

I recently got my "first"...cell phone, or more aptly called, a pocket computer. I was in paying my bill today and noticed protective covers for...$60 and $70, for a freaken piece of rubber..! This fits the same bill as above. A $12 item for $60..! AND...people actually bend over and buy this stuff..! And the funny thing is, these people that buy the outrageously over priced piece of rubber for their pocket computer, HAVE DAMAGE INSURANCE..! So they are paying twice to cover damages that THEY may cause.
By the way, yes, I did buy a protective cover...it cost me $10 on sale, and no, I don't have damage insurance.

I did see one air / oil-water separator that did have some good design thought into it. But along with that...seemed way...over-kill for what it's supposed to do.

Yea, I'll work up an idea or two and build one myself. Won't be as cool as the $450 version, but...it will do the job.

Mike

 

Wow. You are entitled to your opinion but do you need to be so condescending about how other people choose to spend their money or what they assign value to?

I wish you the best of luck in designing your own solution.

 

Well said sir I’m willing to bet we will see post from him in the upcoming months asking for help with his adventures, not that he should seeing how there’s so much info already on these topics Im following you for my own good and curiosity, I’m a techie.