Hmm, not how in worked in my 2014 Z51. Still trying to see how the pressures work and where clean filtered air is coming from. There must be a next flow of air into the crackcase!

The oil/air scavenge pump creates a slight negative pressure in the crackcase. That negative pressure was pulling in clean filtered air from the air intake tube in my 2014 Z51.

Now your saying that not clean air is coming in into the crackcase from the two valve covers from the oil tank. However that is where the air that the scavenge pump is pumping from the Crackcase. Would appear that is a circulation on the same air pump engine blowby.

Would appear that is much less burped air going into the air intake tube through that hose. I'll have to go through some air mass flow balances when I get home and can use a spreadsheet! Guess it could work under certain conditions, i.e. crusing and idle. Have to see how that works at WOT and with air flowing through the PCV system.

In a racing dry sump with large air pumps producing significant vacuum in the crackcase don't believe it would. But there they don't worry about PCV systems!

 

pcv is powered by vacuum at the intake manifold nothing more.

i have personal experience and ownership of several of these

racing dry sump and what we have is not the same, also not the same as a mechanical external vac pump

 

Agree, the PCV at cruising is powered by the engine vacuum. It is sucking crankcase air and blowby into the intake manifold.

The dry sump scavange pump is sucking oil with lots of air into the dry sump tank. The "makeup air" for those flows in my 2014 was coming from the air intake tube though a hose after the air filter to the crackcase. The burped air from the crackcase was going from a hose on top of the dry sump tank that was at a slightly higher pressure to the air intake tube.

It appears to me that is the existing "green labeled line" shown in the LT4 diagram. It can't flow clean filtered atmospheric air from the engine air intake tube to a slightly higher pressure in the dry sump tank.

The green line shown in the LT4 as PCV replacement air, I thought was the "burped air return" as it was in the 2014 Z51. If not, where does the air being sucked out of the crackcase with the oil go? The dry sump tank is at slight positive pressure from that crackcase air being pumped and therefor would think air would flow from the tank to the air intake tube not in the other direction.

Also there is a line going to the bottom back of the engine. Can't tell where it goes or if it "supplying air" from wherever.

I plan on installing a simple two hose "catch can" as I had in my 2014 Z51. It just replaces the short PCV hose from PCV valve to intake manifold. That line still exists on the Grand Sport. Would be simple to add the "can." I don't track so mostly crusing with short occationally bursts of WOT and was collecting ~1 oz of oil/1000 miles. Better collected and dumped than baking on the back of the intake valves, IMO.

Still not convinced the "make up air" for the Grand Sport can come from the engine air intake tube at atmospheric pressure (green labeled line) when the tank is at a slight pressure from crackcase air continually supplied by the oil/air scavange pump. And IF that "green labeled line" is in fact the PCV air "make up" line, where is the line that must "burp air" from the crackcase oil/air scavange pump go?

PCV air is being consumed by the engine and needs a net addition of air from other than the same source from where it is being consumed. The same with the air from the crackcase that passes through the oil/air scavange pump. That air has to be ingested since it contains some oil vapor. That "make up air" was clearly defined in the 2014 Z51 as a second hose barb and line from the engine air intake tube to the crackcase. It no longer exits as such. These flows are still not clear to me so am hesitant to install the simple two line "catch can" until they are.

 

I understand the catch can may not be needed; but the question is will it do any harm?
I have a 2 line Elite from my 2014 Base (no dry sump) that I removed when I sold it - any reason not to install it on my 2018 GS?

 

I took mine from another car and installed it on the GS as you can see in the photo I posted. Who can we trust to tell us if it causes harm or not? I don't think it will harm.

 

I agree it "should not" cause any harm. However that is my opinion. Some are rightly concerned that if they have an engine problem it could effect the warranty. In fact Tadge in a post said it could. IMO it could if installed improperly, oil was not dumped and allowed to fill the can, a check valve was installed improperly etc.

I will install the simple two hose Elite Can that I removed from my 2014 Z51, as a replacement for the short PCV hose that takes crackcase blowby and "stuff" through a PCV valve to the intake manifold. That hose has no check valve and I will not add one that could increase air flow restriction- it's not needed. The Elite Can has very little flow restriction so I believe I could successful argue my position that properly drained it could cause no harm.

However to support that position need to understand all the OEM flows as I did in my 2014 Z51 install. Do not understand those yet for the Grand Sport!

 

JerryU i understand your thought process

but the matter of the fact is that c6 dry sump campaigned successfully without the line you speak of, and it apparently was of such little success or even negative impact on early c7 that it was revised back to c6 type configuration on current model c7 dry sump

i think the hang up is that you are speaking of the air inside the foamy oil to have been created internally and need to be dealt with, when it was already in the system. the system held air and oil, and now it is holding 'oily air' taking the same volume.

something like taking a jug of milk and shaking it up, now the milk is foamy but there was no change in pressure, no burping required.

as long as the oil tank is connected into the system then any pressure fluctuations are shared across the system as a whole. and the end result is the same as non-dry sump scenarios, either being:
:crankcase is in overall vacuum and drawing air in from the cold air tube as first measured by the maf sensor
:crankcase is in overall pressure and purging crank fumes into the cold air tube to be emissions compliant

i also get the sense of the 'drinking of the kool-aid' gm dispenses whenever there is a pcv or dry sump problem. the dry sump 'burping' term in my humble opinion to be a manufactured description based on an inherent design compromise of having this emissions system on a high performance engine. gm will try to shift focus like this any time a customer has a complaint

 

^^^
Sounds like my basic assumption was incorrect; that the line remaining from the engine air intake tube was performing the same function as in my 2014 Z51, of transferring "burped air" from the dry sump tank! As you note, it is actually for providing the fresh, clean air entering the "system" to make up primarily for air that flows from the crackcase through the PCV valve to the intake manifold and in that is ingested by the engine.

Replacing the short PCV hose with lines to and from a catch can should not negatively affect the OEM designed flows.

I'll assume the oil/air scavange pump does not create sufficient air pressure in the catch can such that atmospheric pressure air from the engine intake tube will still flow into the dry sump tank to replace the PCV flow in the "system."

THANKS.

 

This issue has been over thought for a long time. You do not need it. However, if it makes you happy, go for it.

 

disagree. the 'need' is in the eye of the beholder, so some actually do need it and some do not.

most cars operating on public road do not have catch cans.

most also do not have long tube headers and window tint.

all PCV systems have some amount of oil consumption. if you want to reduce what you have, then you are in the market for a catch can.

 

Do you by chance sell catch cans? If so, enough said.

 

yes i sell catch cans and said some do not need them.

i also do not sell headers or tint and say some do need them.

so do you lobby against all modifications, only ones you don't understand, or is it specific to me?

oh wait is it because 'you read about it on the internet' lol thats my favorite one.

relax a little you might just learn something

 

Enough said. Have a nice day.

 

1032 miles since my oil change. Thanks to this piece of crap catch can, all this beautiful oil that was designed to lubricate my intake and coke up my DI engine now sits on the bottom of this can. Sad.

 

Hmm, I don't sell catch cans, am not affiliated with a company who does and have an old can I bought from someone other than David that I will install on my new Grand Sport!

Frankly I don't care if you or anyone else ever adds one! I did the research months before I received my September 2013 built C7 Z51 about high performance cars with DI. Even cars like Ferrari, Porsche and BMW with smaller 4 intake valves per cylinder are concerned about the baking of PCV "stuff" on the back side of their intake valves. The larger intake valves in a Vette run hot since they mostly cool from conduction though the valve seat. The physics at GM is no different than other manufactures! With no gasoline washing the backs of the valves there will be baked on PCV oil. It's referred to as "coking." Suggest you look it up.

Even before DI, gasoline had additives to clean PCV oil from the backs of valves because straight gas was not enough of a solvent. You can add all the extra solvents to gas you'd like, always use Top Tier etc but with DI only air and PCV "stuff" passes over the intake valve backs!

In my 2014 C7 Z51 that I did not track and WOT was used only occationally in short bursts, I collected about 1 oz of oil every 1000 miles for 3 1/2 years. I dumped it out every few thousand miles into the container where I put the oil when I do my own changes. It goes to a recycle center. Better there than baking on my intake valves!

I chuckle about folks with OCD who worry how to shut their car door without finger prints! That is not me, but I do cringe thinking about baked on crud on the backs of my Vette intake valves. Perhaps because I saw those nice clean shinny valves in the 8.2 Liter engine when I assembled it for my Street Rod. I also know that it's 850 Holley double pumper is washing those intake valves when I drive. Even Tadge just said some "coking" can be tolerated, IMO that is like saying so can fingerprints on a door!

There are two engines that I am aware of that are currently using port injection along with DI engine, Toyota and the new 3.6 Liter 567 hp engine in the new Ford GT. They operate the port injection periodically, which will clean that PCV "stuff," as it did in C6 and prior Vettes before it can bake on. Perhaps the new one in the mid engine Vette will do the same! Until then I'll install a catch can to provide some help!

 

I have a UPR dry sump can and a 2017 Grand Sport so I'm dealing with the new routing of the hoses and I don't have that factory hose that comes off the intake to the valve cover. What or how would you suggest I install the can? I see the hose that comes off the front timing cover that goes to the intake, should I just block off one of the ports on the can and put in inline on that intake hose? Or buy an aftermarket intake that has that fitting on the intake tube?

 

Hmm, not at home so can't post a pic I took of the ~8 inch long hose in the front driver's side of my Grand Sport engine. It is similar to what I had on my 2014 Z51. It goes from the PCV valve on the left (sitting in the driver's seat) to the port/hose barb that goes to the intake manifold on the right.

You just remove that hose (as I did on my Z51) and connect the two lines (in and out) on the Can! "In" goes to the PCV valve.

If the Can has two outlets and you want to use both (I elect not to so have it blocked) the you must drill a hole in the air intake tube and insert the other line there. Then that line must have a check valve to prevent air from going into the Can from that line. No check valve is needed if just replacing the PCV hose with a two hose can.

 

any closed can with a single in and single out would connect here to catch normal dirty side pcv oil (vacuum side, where most of the flow takes place during normal part throttle driving)
As seen is my Draft can as it comes within my 'mild' system. the breather is to extend hp capacity of the stock system by being able to purge any building pressure before it causes clean side contamination. It seals when the stock pcv system is able to scavenge in vacuum.

 

^^^ MMS best catch can out on the market that does truly work, Plus a guy that knows what he is doing on the making & working of this can. Robert

 

To each their own. If you see the need, that is all that counts for you.
I have had a lot of Vettes and never have used a catch can. I have never had any engine problems. So, for me I do not see the need. The fun of loving a car is moding it however you wish. Good luck with your choices.