Turbo BS Thread

@mZiggy, somewhere in these posts, some knowledgeable guys posted a link to a great and thorough document about crank case ventilation. This thing straitened me out, with viable options and understanding. Not sure how to do a link, but just google ShopHemi CCV Bible and CCV Bible, Arington motors comes up. Highly recommended read, though their catch can is RICH.

 

@mZiggy This looks like it is piped to the 'dirty' air side of the air filter? If true, I think you want to move that line ASAP, or make sure it has its own air filter. This is the vent line (as opposed to the PCV line). Under all driving conditions that are non-boost (and likely at mild boost), this line is delivering fresh air into the engine crankcase (as Make-up air for the PVC venting that is typically generating vacuum). This NEEDS TO BE CLEAN AIR! Dirty air in here will not have any immediate symptom, but allowing any dirt/dust into the crankcase has definite impact to longevity.

If I am seeing this right, then the next question is where to move this line to. Since you have a Catch-Can on this line, I would put it on the intake pipe after the MAF sensor. Under high boost (or as the engine gets older/more blow-by), air flow in this line changes direction and will be exhaling crankcase pressure. You do not want that oil to contaminate the MAF. Probably what your installer was thinking when they installed it on the dirty air side, letting the air filter remove any remaining oil vapor. Of course you could leave it where it is, and add an air filter to it somehow. I remember many 1970's cars where it vented similar, but had a simple, oil saturated filter fabric over it, within the air filter housing. Like this:

Anyhow, seems to me that:
1) NEVER want dirty air into the crankcase
2) Prefer to not let any oil vapor flow thru your MAF (very sensitive)
3) Is slight advantage to have this line under slight vacuum, after all, if we could keep our crankcase under vacuum all the time, we would. Being on clean air side of air filter has a slight vacuum.
4) Prefer to not feed any oil vapor into the turbo or inter-cooler, But having a catch-can in this line eliminates the vast majority of this concern.

Note that if your Catch-can has a flow direction, you would want the dirty line connected to the crankcase. Even though the airflow will be reversed (into the engine) most of the time (on this line), the CC serves no purpose until the flow reverses under boost, and this is when you want it to remove oil from the airflow, before it enters the intake tract.

Many options, lots to consider, but this makes the most sense to me.

 

As much as I agree that it shouldn't be pre-maf, I've spent so many months fixing so many things from that shop that I honestly don't want to do anything more if I can get away with it, unless necessary.

I'm assuming Mat was able to tune around the extra air being returned pre-maf and I'm assuming/hoping that there's not much contaminates to foul anything up. It's breather side as well, so idk if it's even bringing any contaminates that direction anyway?

I ordered a JLT catch can for that spot on the driver side.

I honestly didn't fully understand what torspd was talking about in his recommendation. If I understood correctly, he's talking about removing the possibility of air/crummy oil following that pcv route at all, but then if I do that idk what the point of having an occ there is.

And at this point, if there's still any hope of Mat honoring his warranty on this kit, I'd like to hold onto that by trying to keep the kit and anything accessory installed as he requests. Honestly there's probably zero way he honors the warranty, his excuses are frequently (to anyone with the kit), "well it doesn't do that on my truck, you must have done something wrong" lol but still...

If I'm understanding my other option correctly for driver side, I can just run the occ in-line post-check valve on that pcv line.

 

You'd have to call me. Much easier to explain by talking.

Let me see if I can find a picture of my setup.

 

Slightly different, since older.

Driver side valve cover, and passenger valve cover both are routed in the catch can.
The hose that used to go from the intake tube ,post MAF is no more.
The black hose on the top of the can, which goes down, is where the breather would be. I just have it elongated to vent by the frame.


This circled port used to be where the PCV hose , from the valve cover to the upper plenum, was attached. That can be capped, or used a a vac/boost reference source.

The top hose on the intake plenum, has a check valve. To not allow boost into my brake booster.



No vacuum hoses on my engine connect the crank case to the intake manifold.

 

The crank case vents, as compressed gasses seep past the rings, then out through the large hoses into the catch can.

 

@Torspd So your crankcase is never under vacuum, but vented pretty well to minimize crankcase pressure while under heavy load/boost. Do you have any oil seepage at gaskets or seals?

I do see how your method (never having crankcase under vacuum) eliminates need for a filter on your vent. It can only breath in when the engine shuts off, as the air in the crankcase cools and shrinks. Not enough volume or velocity to carry dirt.

So your catch-can serves the sole purpose of helping protect the environment.

I am not entirely sold, but I will be studying some more.

 

I have no oil seepage, as no boost pressure enters the crank case, in opposition to boost pressure passing the rings.

I had that long ago, in my early days. Thus learned that thus was the easiest way to prevent that.

The can had a filter up top. Occasionally the vapors would get into the cab. The long hose down prevents that.


Another method, which has been discussed in thus thread before, is to use the exhaust as a vacuum source for the crank case.

Filter>driver valve cover>passenger valve cover>catch can> angled fitting into exhaust. (Better for a single turbo setup on the Tacomas. Could be adapted for twins.) The venturi effect would always keep that style of setup under vacuum.

 

@Torspd OK, Got it. No hose connecting intake to Crankcase = no way for boost pressure to enter crankcase, except past the rings (which is always happening, more so when boosted). I do agree that the check valve is unreliable after passing messy crankcase air, so while failing must be considered. This issue is remedied by your system.

Been reading for months, and yes I just recently ordered the exhaust venturi part. But, I have concern for if this fitting will sometimes see back pressure? That would then defeat the vacuum advantage AND require a check valve in this line, plus separating left and right again, and going back to having one vent go from opp side valve cover to clean air just after the MAF. This line can relieve blow-by pressure at times when the exhaust stops producing vacuum.

This conversation has brought me closer to your system; without regard to emissions, your is simple, solves much of the concerns, and above all is a Fail-Safe. All others either have more downside, or rely on check valves. Unless I discover that the exhaust venturi is always sucking. Though I am not fully decided, yet.

BTW Thanks to all that contribute here, my understanding of turbo related systems is largely due to the people on these posts!! Great sound-board.

 

Regardless, I'd already ordered the JLT catch can before you'd replied with your initial response regarding your capped off solution @Torspd

I really do appreciate all the help however. Invaluable.

It arrived about an hour ago, just installed it.

 

What I find most irritating however is that yet again I'm fixing something that should've been completed and super simple to do by the 1st shop that did the install.

It's a fucking oil catch can. That's it. However easy it was for me to throw that in there....Jesus fuck, your self proclaimed "turbo guy", your performance vehicle tech for the shop couldn't fucking do that? Lol smh...ugh.

 

Someone wiser, once enlightened me to the flow patters of N/A versus F/, in the engine. Then it all became clear.

 

I had a much better understanding of F/I flow pattern 6 or 7 years ago when I last had a boosted car. Turbo from factory though. But still. Managed to forget everything in the time since.

 

This hose, as is, will need a check valve in it. To prevent positive pressure from going into the crank case. Or cap the nipple on the intake side. Letting that hose dangle.

 

That hose has a check valve already. That's the valve I'd been referring to in the past. That spot with the electrical tape is where it's at.

 

The back pressure you speak of, would mean that your turbo's exhaust is too restrictive, and/or your angled fitting is placed for a bad priority of flow.

Another method for a catch can would be this.

Filter>valve cover in>other valve cover out> catch can>hose or tube pre-turbo.

That method will also allow the oil vapors to be combusted and gone through the catalytic converter (should you have one). However. It can also lead to oil build up on your impeller, intercooler, and TB, if the hose sizes and can design are not good enough.

 

Ok. Gotcha.

 

I am considering: a tap right after MAF >catch can>valve cover (typically airflow in to motor), then other valve cover>catch-can>Tee > Ck-valve to intake manifold (typically vacuum); Other line off Tee>ck-valve > filter in dirty air side of airbox (typically no flow, is under intake vacuum, Ck-valve closed by vacuum, but allowed to exhale while under heavy boost or if the intake ck-valve leaks boost)

More complicated, but what I like is:
- Provides vacuum on crankcase under normal driving (non boost)
- Under vacuum, air into the Crankcase is metered (sucking in after MAF)
- If Manifold Ck-valve leaks, leaked boost will vent to air-box, not just pressurize crankcase
- if Manifold Ck-valve leaks often, I will see the oily evidence each oil-change when i inspect the air filter, indicating to service the Ck-Valves.
- When in High Boost, both lines flow out (is why both lines get catch cans)
- Does a good job of minimizing how much oil enters pre-turbo. Dirty Oily air feed pre-turbo is limited to only while under boost, and is only half the volume, with the other half venting to the airbox.
- The venting into the airbox gets its own filter, plus on occasion of boost, Oil laiden air gets filtered by the regular air filter too; this should ensure the MAF never sees oil.
- Even under boost, there is a slight vacuum at one valve cover, due to connection after MAF (slight pressure drop across the air filter)
- This system fails safe, no way for crankcase to get boosted.
- This system burns everything that gets past the catch-cans, except possibly some oil collecting in the bottom of the air box.
- Most crankcase venting enters intake post turbo and intercooler (except while under boost).

 

yes, maybe. I am going with URD y-pipe and back. But Summit Racing got my attention on the exhaust venturi, with stating that it does not work on systems with a muffler. This got me wondering if under the various throttle conditions, this thing might sometimes be blowing? Also, with considering where to put it in the exhaust. Pre-turbo seems dumb, Pre-cat is feeding oil to the cat, and unburned gas, often without oxygen to burn it, seems troublesome to the cat. Post Cat is probably safer, but anything that gets past the catch-can just collects in the exhaust until it gets hot enough to vaporize it, but not likely burning it. Leaves room for improvement.

There is good reason why factory autos have so many hoses under the hood. Seems to me that your system is good and simple, or go full blown complicated, but fail-safe.

 

How much did they charge you for that harness? Are you going to keep the stock ECU around for some function or completely standalone?