[Lepsss]

Can someone tell me if I can use a mishimoto catch can for a supercharged application? I know I would have to remount the cc in a new spot with some new tubing but would it still do the job correctly?

[Lepsss]

Hey do u know if I’m able to use my mishimoto catch can that I’ve been using NA with a supercharger application? I know I’d have to remount it and probably use new tubing but would it still work correctly?

[protovack]

its all a fine balance between performance, fuel economy, and emissions. The engineers are forced to design a PCV system that tries to satisfy everyone and as a result some sacrifices are made. This the price we pay for GDI engines that get incredible fuel economy and have incredible performance available as well. Most people could drive their GDI engine for its entire service life and never notice the 10% drop in power and throttle response due to coking. Enthusiasts have several options, either use an oil separator, or pop off your intake manifold every 20-30k and clean the ports and valves. For me personally, I think it is more annoying to worry about filling up and emptying a catch can. I'd rather just drive my car and not worry about it. Someday, I'll go to my local mechanic and pay him a few hundred bucks to clean everything out. It's a quick and easy job and doesn't require ordering any parts. And it pales in comparison to the kind of maintenance that used to be routine on older engines. Think about it. An engine that will go 150-200k miles without much more than a valve/intake cleaning every once in a while. That amazing. And the funny thing is, even with a catch can, you still get some coking and so eventually even catch-canned engines would benefit from a cleaning. So sure, use a catch can if you want. It's one solution to the problem. I just get irritated when people insist its the best, or only solution.

[dmcmahan60]

Well said Protovack and thanks.

[DIYguy]

I second that thought.

As I have posted before (and got an immediate rebuttal from the Elite guy) the intake on my LGX V6 is bone dry.
I checked it literally just last week when I put a new throttle body on it.
Still dry and clean at 46k miles.
And the intake valves were only very slightly coked when I had the manifold off earlier this year while indexing my spark plugs.
So there is nothing to "catch" coming from its crankcase ventilation system and no particular cause for concern, at least in my case.
I expect I may have to do a walnut shell blast at around 100k miles, and will do it myself. No big deal.

The counter argument offered to the factory LGX air/oil separator doing such a good job was that all of that stuff must therefore be returning to inside the engine.
Fair enough. No argument.
But for that and other reasons I change my oil and filter at 3500-4000 miles or at 50% on the oil reminder whichever comes first, not at 13,000+ miles as was shown in the earlier posting. Cheap insurance IHMO.
To me, stretching the oil changes out to whatever the reminder optimistically reports is false economy anyway if one plans to keep their vehicle a long time.

Regardless, adding in a system such as was shown in a prior post is out of the question because I reside in California.
It would not pass the technical inspection during a smog test (I have had vehicles fail tech inspection for much less).
Even if I plugged up the hole that I'd have to drill in the manifold it would be a risk depending upon how anal the inspection tech wanted to be.

So my solution (just one of many possible of course) is more conservative oil change intervals for all of our vehicles.
FWIW.

P.S. I have had catch cans on older vehicles and they definitely did work.
But on the LGX I honestly feel no pressing need.

[cellsafemode]

Same, in California... Very little residue in my can, never any in the clean side can (I have two).

My stuff is just in line, so it is simple to take out if needed for emissions testing.

[95 imp]

Originally Posted by DIYguy

I second that thought.

As I have posted before (and got an immediate rebuttal from the Elite guy) the intake on my LGX V6 is bone dry.
I checked it literally just last week when I put a new throttle body on it.
Still dry and clean at 46k miles.

Do you drive conservatively? FI, juiced, and motors that are at full throttle, or short trips w/o fully warming the motor, will have more blow-by and more to "catch".

Originally Posted by DIYguy

And the intake valves were only very slightly coked when I had the manifold off earlier this year while indexing my spark plugs.
So there is nothing to "catch" coming from its crankcase ventilation system and no particular cause for concern, at least in my case.
I expect I may have to do a walnut shell blast at around 100k miles, and will do it myself. No big deal.

Try this stuff:

https://www.crcindustries.com/produc...-oz-05319.html

Originally Posted by DIYguy

But for that and other reasons I change my oil and filter at 3500-4000 miles or at 50% on the oil reminder whichever comes first, not at 13,000+ miles as was shown in the earlier posting. Cheap insurance IHMO.

So my solution (just one of many possible of course) is more conservative oil change intervals for all of our vehicles.
FWIW.

Actually, I'd argue that it will make the coking problem worse. Why? New oil has a wide range of molecules. For the sake of argument, let say light, medium, and heavy.

When it's in your car, you are actually "refining" it. The heat boils off the lighter molecules, then more medium ones. If you leave it in long enough, the oil gets thick and "tar" like.

Now am I saying never change your oil? Of course not.

What I am saying is the engineers have millions of dollars to study oil in cars and write algorithms to tell you the life of the oil. Back in the old days, we didn't have this technology, nor the sophisticated cars/oils and it HAD to be changed more often.

You're introducing new oil every oil change and could be worsening the coke problem by going thru that "refining" process more.

The oil is getting "broke in" and then you drain it for fresh oil and start burning off the light stuff again.

And, yes I know, synthetics are "more stable" than conventional oils.

Won't argue that fact.

I will argue that "more" isn't 100% and it still occurs.

[Elite Engineering]

To add more detail into the LGX engine's PCV system, the LGX has no Positive Crankcase Ventalation/evacuation system. GM to reduce the rate and severity of the intake valve coking deleted the "positive" function and uses a "passive" system that lets pressure build and vent into the main intake tube. There is NO connection to the intake manifold. Fresh air enters both valve covers, and the foul vapors are pushed by pressure out the rear of the valley cover. So the engine life is sacrificed by leaving much of the combustion by-products in the crankcase increasing engine wear and premature damage. The goal is to get these past the warranty period before coking symptoms appear.


Here are pictures to show you:


Here are the PCV valves that are located at the front of each valve cover:





Air enters here IF suction is pulled and enters both valve covers. These only flow in, so as most of the time the engine is running, since no IM vacuum is used, there is pressure in the crankcase and that will build and vent out the passive foul side hard line as shown here:






So, very little oil is actually entering, and coking severity has been reduced to 50% plus of what the LLT and LFX did, but an oil analysis will show the oil condition. Here is one with our system installed with over 13,000 miles as we convert it not only back to a "positive" evac system, but also to full time evacuation so were flushing and removing most of the combustion by-products before they have a chance to mix with the oil:






This is totally different than the LT based engines which still have a "Positive" system.

[cellsafemode]

the leap of logic being made above is that the combustion byproducts being left in the oil are causing damage vs adding vacuum to suck the vapors constantly vs the passive setup or any vacuum caused by the intake.

Improving oil quality over average by doing that is not in question, it's if it matters or is it unnecessary overkill. What would be needed is the LGX (not another motor) showing below average oil tests with the stock setup at factory recommended oil change intervals, and then using the same intervals and same oil and filter as in the stock test, in relatively the same environment showing average or better than average oil quality (with the catch can).

Simultaneously, comparing the intake/exhaust valves for buildup. Since one of the concerns I'd have with adding vacuum is that you are pulling significantly more oil vapor in and if the can catches say 95% of all oil vapor ...and the stock setup barely sends any ...that's 5% of close to nothing getting into the throttle body. But a vacuum setup bringing a lot more oil vapor for the can to catch, will let 5% of that thru and that can be many times more oil getting into the intake. A compromise that may be worse than the benefit provided if we're not even sure that the stock "contaminated" oil is actually detrimental or if it's OCD.


edit: That above test setup would convince me that the addition of vacuum to the catch can configuration, and indeed, catch cans in general for this motor, is objectively beneficial. Showing tests of other engines that dont use the same pcv and oil separator and combustion system will not. Showing improvements to oil with no reference that the stock test results are harmful will not. Showing pictures of intake valves in other engines will not. Until then, I consider them to be an overkill mod. Akin to buying the best oil and filters and changing them before needed. With the caveat to the concern mentioned above about adding vacuum increasing the oil that makes it past the catch can since the catch can will never catch 100% and whatever it misses is going to be increased if the vacuum increases the oil vapor it's getting as input.

[DIYguy]

I agree with cellsafemode.
I don't want to do anything that could add any amount of oil mist to the intake (and I will look into the CRC product, thanks 95 imp).
Plus, for better or worse, I live in the fabulous PRC, so modifying the intake manifold or the crankcase vent system is beyond any question of legality to start with.

As for the argument that changing the oil more frequently could be in any way harmful, sorry, not buying it.
My dad worked for an oil company and was one of the people who helped develop the pin wear test protocol for engine oil that became part of the SAE test standards.
He knew quite well what he was doing (PhD actually) and taught me a lot about engine oil and the mechanisms by which it wears out.
Oil deteriorates as it is used, period.
Even in things like air compressors which have no combustion byproducts to deal with it wears out from shear forces, and so do additives.
So you are simply not refining it by using it.

And of course Elite chimed in.
I am emphatically NOT disparaging their product or discouraging you from buying a setup if you are so inclined.
However-
By their own words- "very little oil is actually entering, and coking severity has been reduced to 50% plus of what the LLT and LFX did, but an oil analysis will show the oil condition."
Yes, I don't want ANY of that stuff going through my intake and especially not into the catalytic converters because it will harm them...!!
Find another way to deal with it.
I totally agree that on engines that have PCV systems a catch can is only a benefit.
Assuming it is done right of course, which Elite's definitely appear to be.
So again I am not arguing against their product or anything like them in that situation.
For the LGX however, change your oil....!!
And 13,000 miles on an oil change? Really? Seriously?

BTW, I do drive conservatively.
I do not "track" my car, never have, never will.
My typical trip is to start it up, drive 38 miles, shut it off, repeat.
I completely understand that if someone is on the throttle all the time and drives short trips it will gum things up faster.
But I will repeat that letting it go to what the manufacturer's oil minder says as a change interval is borderline foolish.
And of course their own oil reminder will reduce the interval based upon that sort of usage.
Remember please that just like the much-reviled AFM system, they programmed that to meet some EPA/treehugger goal of minimizing oil changes.
Do you buy into that?
With your engine and your wallet?

[95 imp]

Originally Posted by DIYguy

He knew quite well what he was doing (PhD actually) and taught me a lot about engine oil and the mechanisms by which it wears out.
Oil deteriorates as it is used, period.
Even in things like air compressors which have no combustion byproducts to deal with it wears out from shear forces, and so do additives.
So you are simply not refining it by using it.

Not going to argue that fact at all. Oil does wear out. My contention was the lighter fractions causing the coking issue as heat boils them off.

Originally Posted by DIYguy

….they programmed that to meet some EPA/treehugger goal of minimizing oil changes.
Do you buy into that?
With your engine and your wallet?

Valid point.

[DIYguy]

I believe that we are actually on the same page.

I fully take your point regarding the lighter volatiles.
That is in fact one of the reasons to use the newer oils that are specifically formulated for GDI engines (and are labeled as such).
They are formulated to prevent things like that from happening by minimizing the volatiles in the first place (among other things).
It is also a good reason to change your own oil so you know precisely what is being put into your engine (my dad changed his own oil until he was into his 80's and so will I).

Oh and don't forget that unlike the pre-cat days, you really shouldn't be using oil or additives that have loads of ZDDP or similar compounds in it.
For example- https://www.liveabout.com/debunking-...-legend-726162
There is a reason why "modern car" oils are different and need to be.

Look it another way, if the lighter components are a smaller (or more likely minuscule) fraction of the modern oil that you should be using, what there is of it is likely to pass the valves (relatively) harmlessly until it is basically gone.

And yet another way- how much oil does your engine consume between changes?
Mine uses as close as I can measure- none.
Sure, it must use use some to lubricate the valve guides and crank seals.
But I sure can't measure it.
Teaspoons maybe?
The simple fact that my intake manifold is bone dry (and I literally mean close to white glove clean) means that there can't be much at all passing through it to get to the valves.
Most likely the little bit that is coming down past the valve seals is what is causing the very minor coking of the intake valves that I have observed.
Naturally no catch can will stop that from happening.

Change your oil........

[Aragorn]

No track time or drag racing here, but I dump a couple ounces every thousand or so miles.

[DIYguy]

That is actually quite good.

My last commuter car drank, leaked, spewed or otherwise disappeared about a quart every 1300-1500 miles, and that was after a comprehensive, careful overhaul with top shelf parts.
It was even worse before that.
And the pistons, cylinders and plugs ran quite clean despite it all.
It was just the nature of the beast, sadly (a known issue with that particular model).
The intake manifold was filthy dirty and slimy all the time and the intake valves were always coked.
The back side of the throttle plate was always a mess despite being cleaned periodically.
It poisoned the catalytic converters after about 100k miles as a direct result.
So it became one of my first catch can fittings (and it worked wonders).
Trust me, I am not against catch cans.
They just need to be fitted with some regard to where or if they are actually needed.

I do have a bit of practical experience in regards to potential damage, so I am very, very respectful of what goes into the crankcase and fuel tank of my Camaro.