Is the Catch Can necessary
Pro
Joined: Apr 2014
Posts: 568
Likes: 109
From: South Carolina
So did we all buy a piece of S/..,//t time-bomb i am confused Hey GM how about chiming in here and put this to Rest
Maybe we should replace the Dextos special oil everybody is getting rid of maybe that's the fix
Maybe we should replace the Dextos special oil everybody is getting rid of maybe that's the fix
Burning Brakes
Joined: Jul 2013
Posts: 1,147
Likes: 107
From: Cherry Hill PRNJ
Only if it screws something up.....I mounted one and was getting about 1/4 tsp per month the way I drive, took it off and sold it. Don't need the clutter and don't believe that chev "forgot it" based on an article written by a GM'ER to mike @ Criswell:
I was the one that contacted someone from the Stingray Consultant team from GM...Here is what he wrote back on this matter.
"The Stingray was evaluated with over one million development miles on 200 captured test fleet cars. There are tens of thousands of direct injection vehicles on the road from General Motors alone. During the evaluation hundreds of engines were literally torn down in to part piles and evaluated. There are hundreds of thousands of LSx family of motors (where part of this catch can hype started) on the roads and the many of these motors are running well past 250,000 miles without a catch can.
The cars have a 100,000 mile powertrain warranty and that includes mechanical failure of the engine. Trust me when I tell you that there are not reams of data (not even pages of data) on cars coming up lame because of oil at the MAF. It just isn't the problem that the "internet" makes it out to be. When you ask a GM Powertrain engineer about a catch can the reply is that the only thing you get is added weight.
In looking at the extra effort and added cost that went in to the Stingray, do you really believe for one second that if a $20.00 part attached to the engine would improve reliability, limit warranty claims and replacement costs, that GM wouldn't have put it on if it was necessary as part of their evaluation?
Every single GM engineer that I have spoken with told me in one form or another that a catch can is predominately a "gimmick" device created by tuners looking to make a few extra bucks on their engine modifications.
As a by-product of the PCV system, excess oil vapor is recycled to prevent it from leaching out in to the environment. It will condense back in to liquid if the temperature and environmental conditions are right. A catch can is an oil separator device. It allows the heavier oil in liquid to condense in the bottom of the can and only pass the air (gases) back. This is basically the same thing that is happening at the front of the MAF where most of the oil can be found.
The theory is that this oil in the intake system will collect on the valves and in the cylinders and cause excess carbon deposits. The catch can will reduce (not eliminate) oil pooling in the MAF.
Where the plan breaks down is that there aren't thousands of cars detonating because of the oil. As I told you on the phone, This isn't new. The engines are designed to deal with a quantity of oil mist presented via the intake.
You asked what I should tell the customer, my answer is I'm not sure because I don't know what his question is. If the question is is this normal? The answer is yes. If the question is should I put a catch can on? The answer is what ever makes you feel better. If the question is do I need a catch can? The answer is a resounding no. If the reply is that they saw it on the internet, apologize politely and tell them virtually every thread about it has started with a vendor selling a product or a consumer that was fooled by the hype and trying to make themselves feel better about their purchase by getting others to agree with them.
If he has concerns about his condition he should take the car to his dealer for evaluation.
Here is my standard response to the dozens of emails I get each year with a link to a thread like you posted (and often, that very same thread).
Simply stated, absolutely not on the catch can. It simply isn’t warranted for any street driven car. We can talk in more detail about it tomorrow and Dan will appreciate it as I’ve all ready had this conversation with him as well. Since the advent of the PCV system, cars have released some oil in places where it wouldn’t normally have gone in a fully sealed system. It ends up in vapor which condenses back in to liquid form in the intake path. As a result of that, the system is designed to ingest and subsequently digest some extra oil. Higher revving produces more oil and repeated higher revving (drag racer, track duty car, etc.) would be in the realm of uses that I might consider adding the can. Daily driving, occasional back road romp or stop light to stop light burst, not so much.
With all of that said, they won’t hurt anything. For those that don’t want to take my word for it, can feel comfortable adding it but it won’t make an appreciable difference in the life of the motor or the efficiency of the system.
If you dig deep enough in to forum information about catch cans, all roads generally lead back to a performance tuner, aftermarket part supplier or fabricator who has a vested interest in selling catch cans." Stingray Consultant
Mike Furman ~
"Be kinder than necessary, for everyone you meet is fighting some kind of battle"
I was the one that contacted someone from the Stingray Consultant team from GM...Here is what he wrote back on this matter.
"The Stingray was evaluated with over one million development miles on 200 captured test fleet cars. There are tens of thousands of direct injection vehicles on the road from General Motors alone. During the evaluation hundreds of engines were literally torn down in to part piles and evaluated. There are hundreds of thousands of LSx family of motors (where part of this catch can hype started) on the roads and the many of these motors are running well past 250,000 miles without a catch can.
The cars have a 100,000 mile powertrain warranty and that includes mechanical failure of the engine. Trust me when I tell you that there are not reams of data (not even pages of data) on cars coming up lame because of oil at the MAF. It just isn't the problem that the "internet" makes it out to be. When you ask a GM Powertrain engineer about a catch can the reply is that the only thing you get is added weight.
In looking at the extra effort and added cost that went in to the Stingray, do you really believe for one second that if a $20.00 part attached to the engine would improve reliability, limit warranty claims and replacement costs, that GM wouldn't have put it on if it was necessary as part of their evaluation?
Every single GM engineer that I have spoken with told me in one form or another that a catch can is predominately a "gimmick" device created by tuners looking to make a few extra bucks on their engine modifications.
As a by-product of the PCV system, excess oil vapor is recycled to prevent it from leaching out in to the environment. It will condense back in to liquid if the temperature and environmental conditions are right. A catch can is an oil separator device. It allows the heavier oil in liquid to condense in the bottom of the can and only pass the air (gases) back. This is basically the same thing that is happening at the front of the MAF where most of the oil can be found.
The theory is that this oil in the intake system will collect on the valves and in the cylinders and cause excess carbon deposits. The catch can will reduce (not eliminate) oil pooling in the MAF.
Where the plan breaks down is that there aren't thousands of cars detonating because of the oil. As I told you on the phone, This isn't new. The engines are designed to deal with a quantity of oil mist presented via the intake.
You asked what I should tell the customer, my answer is I'm not sure because I don't know what his question is. If the question is is this normal? The answer is yes. If the question is should I put a catch can on? The answer is what ever makes you feel better. If the question is do I need a catch can? The answer is a resounding no. If the reply is that they saw it on the internet, apologize politely and tell them virtually every thread about it has started with a vendor selling a product or a consumer that was fooled by the hype and trying to make themselves feel better about their purchase by getting others to agree with them.
If he has concerns about his condition he should take the car to his dealer for evaluation.
Here is my standard response to the dozens of emails I get each year with a link to a thread like you posted (and often, that very same thread).
Simply stated, absolutely not on the catch can. It simply isn’t warranted for any street driven car. We can talk in more detail about it tomorrow and Dan will appreciate it as I’ve all ready had this conversation with him as well. Since the advent of the PCV system, cars have released some oil in places where it wouldn’t normally have gone in a fully sealed system. It ends up in vapor which condenses back in to liquid form in the intake path. As a result of that, the system is designed to ingest and subsequently digest some extra oil. Higher revving produces more oil and repeated higher revving (drag racer, track duty car, etc.) would be in the realm of uses that I might consider adding the can. Daily driving, occasional back road romp or stop light to stop light burst, not so much.
With all of that said, they won’t hurt anything. For those that don’t want to take my word for it, can feel comfortable adding it but it won’t make an appreciable difference in the life of the motor or the efficiency of the system.
If you dig deep enough in to forum information about catch cans, all roads generally lead back to a performance tuner, aftermarket part supplier or fabricator who has a vested interest in selling catch cans." Stingray Consultant
Mike Furman ~
"Be kinder than necessary, for everyone you meet is fighting some kind of battle"
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,050
Likes: 12,417
From: NE South Carolina
[attach]
This is a catch can from a Base C7 with only 300 miles since installed. Please understand that this oil would've ended up on the valves if it wasn't caught in this Catch can causing caking on the valves. Direct injection is really great, but gas won't wash the valves off when oil from the PVC allows oil to enter the intake.
This has been talked about before, but I think it is important to address this situation again. Yes, the catch can is very necessary.
Capt Bob
This is a catch can from a Base C7 with only 300 miles since installed. Please understand that this oil would've ended up on the valves if it wasn't caught in this Catch can causing caking on the valves. Direct injection is really great, but gas won't wash the valves off when oil from the PVC allows oil to enter the intake.
This has been talked about before, but I think it is important to address this situation again. Yes, the catch can is very necessary.
Capt Bob
Not only do I agree but a GM enginner with the credentials to be able to speak to the issue did just that in the December 2014 issue of Hot Rod Magazine! They interviewed this GM Engineer who’s title is Assistant Chief Engineer for Small Block V8’s! This is not just any GM spokesman!Here is what this engineer, John Rydzewski, said, paraphrasing:
" A PCV separator, which is unique to the LT4, was developed to keep oily air from being drawn through the intake, where it could end up collecting on the back of the intake valves. A little bit of oil on a port injected engine can help lubricate valves, but because all C7 V8's are direct injected, there's no fuel washing the back of the intake valve. That means oil in the PCV system can end up sticking to the back of the hot valves impeding airflow and eventually preventing the valves from seating properly!”
The intake valves in a high performance engine operate at high temperatures. Ferrari and Porsche have had DI for more years than GM in high performance engines. Read their forums, there are problems with build-up on the intake valves that effects performance, it’s called “coking.” Ferrari was disussing the use of a fluid purge on the intake at each oil change (sounds expensive.). BMW has a mechanical cleaning method to remove "coking" deposits that was shown in a forum thread (very expensive!) Toyota has one DI engine that also has port injection that is activated from time to time to help clean the intake valves! You may remember the gasoline ads that show the extra additives to stop the build-up of baked on carbon on the intake valves on cars with port injection or carburetors. With DI no gasoline goes past them now! No more help if you “blow it out” with a high RPM blast!
“Coking” is an issue with high performance DI engines. How big an issue in the Corvette, apparently Rydzewski Assistant Chief Engineer for Small Block V8’s thinks it is enough to discuss the issue in in a magazine article!
Is a “Catch Can” the whole solution? Probably not but it is a help.
Why doesn’t GM install one in the Corvette? Because it requires maintenance and most owners don’t even check oil levels as often as recommended is probably one reason.
Time will tell how much of an issue it is and how much performance will suffer. But in the meantime, it can’t hurt and the oil some folks are finding in their catch cans is sure better collecting in the can than in the intake and baking on the back of the valves! The design and media in a quality catch can condenses oil vapor coming from the PCV system and reduces the amount going into the intake.
Last edited by JerryU; Jan 30, 2015 at 07:52 AM.
Racer
Joined: Nov 2013
Posts: 347
Likes: 54
From: Helotes (NW of San Antonio) TX
cheap insurance, for sure.....
$80k car with 5 free dealer oil changes, who by the way can't install the correct dealer recommended oil or the appropriate amount makes a catch can and seperator cheap insurance indeed, for quite a few C7 owners.
it amazes me that someone half way across the country will say that something doesn't occur in my car when I am witnessing it first hand. Hmmmmmmmm.
do whats right for you and your situation and dont just follow the crowd.
it amazes me that someone half way across the country will say that something doesn't occur in my car when I am witnessing it first hand. Hmmmmmmmm.
do whats right for you and your situation and dont just follow the crowd.
Burning Brakes
Joined: Jul 2011
Posts: 841
Likes: 72
From: NC
I'm another one that's on the fence over adding a Catch Can. I like to do a lot of research on a product before I purchase it. Here's a few things I found out...
For grins I contacted my dealerships service department to get their opinion on adding a Catch Can, and whether adding one would negatively impact my warranty. I expected to hear adding a Catch Can is not necessary. This would make perfect sense to me considering dealerships make good money fixing the results ingested oil vapors (clogged Mass Air Flow Sensors, valve deposits, oil in the intake, etc). But to my surprise my Service Manage said, "The LT1 engine already has a Catch Can." Me: Well... uh... okay. Perhaps he meant the Air Box is doubling as a Catch Can? Who knows, but at that point I thought it was wise not to ask additional questions.
Out of respect for my dealership I won't mention names. (And no comment was given on whether a Catch Can would negatively affect my warranty.)
I also contacted a popular TV automotive personality that provides weekly automotive advice and asked his opinion on adding a Catch Can (name and TV show not important). His comments are paraphrased below:
* After monitoring the system for awhile, if there are issues install the Can but keep in mind most pictures you see on the internet of cars with oil deposits in the intake, are cars that have been run hard.
* If one is getting excess blow-by, get it checked at the dealer and log the problem under warranty.
* Adding a Catch Can may cause warranty issues.
* Maintenance of the Catch Can is important. Not emptying the Can periodically could cause a big gulp of oil to be ingested into intake during hard acceleration, possibly causing serious damage (hydro-lock).
The video below really got my attention. It shows what a LT1 can look like if run hard, although what surprised me is this C7 only has 5,500 miles. Note oil deposits are already growing on the Mass Air Flow Sensor, and there are substantial oil deposits in the intake. And if you click on the 2nd link (which pops up) you'll also see deposits on the valve stems. All this from PCV vapors? Or did this engine have too much oil in it to start with? Your guess is as good as mine:
But one general theme that I've read and heard often is, the harder you push the engine (or if you over fill the engine oil), the better chance you'll have of ingesting oil into the intake. And while I don't normally push my C7 hard, I do find it a bit disturbing that if I did, there would be a negative impact. After all... it is a Vette, right?
My biggest issue is whether adding a Catch Can can negatively affect my warranty. I'd be interesting in hearing from anyone who has added a Catch Can and has had any negative warranty issues. Or even received negative comments from their service department over this mod.
For those ready to pounce on my posting, hold up. I'm not trying to convince you one way or the other about the Catch Can. Be it right or wrong, this is just info I've turned up during my research.
In the end, we all roll our own dice and make our own decisions. As for me, as long as it doesn't negatively affect my warranty, I'm leaning towards adding a Catch Can, probably the Elite [Best] system. I see it as cheap insurance and possibly adding to my engines longevity.
For grins I contacted my dealerships service department to get their opinion on adding a Catch Can, and whether adding one would negatively impact my warranty. I expected to hear adding a Catch Can is not necessary. This would make perfect sense to me considering dealerships make good money fixing the results ingested oil vapors (clogged Mass Air Flow Sensors, valve deposits, oil in the intake, etc). But to my surprise my Service Manage said, "The LT1 engine already has a Catch Can." Me: Well... uh... okay. Perhaps he meant the Air Box is doubling as a Catch Can? Who knows, but at that point I thought it was wise not to ask additional questions.
Out of respect for my dealership I won't mention names. (And no comment was given on whether a Catch Can would negatively affect my warranty.) I also contacted a popular TV automotive personality that provides weekly automotive advice and asked his opinion on adding a Catch Can (name and TV show not important). His comments are paraphrased below:
* After monitoring the system for awhile, if there are issues install the Can but keep in mind most pictures you see on the internet of cars with oil deposits in the intake, are cars that have been run hard.
* If one is getting excess blow-by, get it checked at the dealer and log the problem under warranty.
* Adding a Catch Can may cause warranty issues.
* Maintenance of the Catch Can is important. Not emptying the Can periodically could cause a big gulp of oil to be ingested into intake during hard acceleration, possibly causing serious damage (hydro-lock).
The video below really got my attention. It shows what a LT1 can look like if run hard, although what surprised me is this C7 only has 5,500 miles. Note oil deposits are already growing on the Mass Air Flow Sensor, and there are substantial oil deposits in the intake. And if you click on the 2nd link (which pops up) you'll also see deposits on the valve stems. All this from PCV vapors? Or did this engine have too much oil in it to start with? Your guess is as good as mine:
But one general theme that I've read and heard often is, the harder you push the engine (or if you over fill the engine oil), the better chance you'll have of ingesting oil into the intake. And while I don't normally push my C7 hard, I do find it a bit disturbing that if I did, there would be a negative impact. After all... it is a Vette, right?
My biggest issue is whether adding a Catch Can can negatively affect my warranty. I'd be interesting in hearing from anyone who has added a Catch Can and has had any negative warranty issues. Or even received negative comments from their service department over this mod.
For those ready to pounce on my posting, hold up. I'm not trying to convince you one way or the other about the Catch Can. Be it right or wrong, this is just info I've turned up during my research.
In the end, we all roll our own dice and make our own decisions. As for me, as long as it doesn't negatively affect my warranty, I'm leaning towards adding a Catch Can, probably the Elite [Best] system. I see it as cheap insurance and possibly adding to my engines longevity.
Last edited by Rave; Jan 29, 2015 at 10:58 PM.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,050
Likes: 12,417
From: NE South Carolina
Note I am NOT advocating this be done on your road going Vette! In fact if you did it where it is most effective, near the exhaust collector you’d quickly destroy the catalytic converter!
Some of us can remember what was done before PCV systems. The crankcase was vented with a ~1 inch tube that came from the crack case and exited just below the oil pan. As the car moved it pulled out the blow by etc. into the atmosphere. Cars with bad rings would smoke heavily. No one advocates doing that!
Exhaust Scavenging, Simple and Adds HP
Last edited by JerryU; Jan 30, 2015 at 05:27 PM.
Melting Slicks
Joined: Dec 2011
Posts: 2,690
Likes: 116
From: Richmond area Va
OP, Catch can or no catch can, I really don't care, but I don't want oil from the PVC entering the intake and coking my valves. If anyone has a better method I would sure like to know. This is not only a problem with GM, but every direct injection engine. If you think this condition doesn't exist you have the right to ignore it.
you only have to dump oil out of your intake once for it to be too many times.
this new engine has more air flying around in it than any other chevy ive seen (that is running right lol) and with the increase in air comes the oil mist.
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E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,050
Likes: 12,417
From: NE South Carolina
Not only do I agree but a GM enginner with the credentials to be able to speak to the issue did just that in the December 2014 issue of Hot Rod Magazine! They interviewed this GM Engineer who’s title is Assistant Chief Engineer for Small Block V8’s! This is not just any GM spokesman!Here is what this engineer, John Rydzewski, said, paraphrasing:
" A PCV separator, which is unique to the LT4, was developed to keep oily air from being drawn through the intake, where it could end up collecting on the back of the intake valves. A little bit of oil on a port injected engine can help lubricate valves, but because all C7 V8's are direct injected, there's no fuel washing the back of the intake valve. That means oil in the PCV system can end up sticking to the back of the hot valves impeding airflow and eventually preventing the valves from seating properly!”
The intake valves in a high performance engine operate at high temperatures. Ferrari and Porsche have had DI for more years than GM in high performance engines. Read their forums, there are problems with build-up on the intake valves that effects performance, it’s called “coking.” Ferrari was disussing the use of a fluid purge on the intake at each oil change (sounds expensive.). BMW has a mechanical cleaning method to remove "coking" deposits that was shown in a forum thread (very expensive!) Toyota has one DI engine that also has port injection that is activated from time to time to help clean the intake valves! You may remember the gasoline ads that show the extra additives to stop the build-up of baked on carbon on the intake valves on cars with port injection or carburetors. With DI no gasoline goes past them now! No more help if you “blow it out” with a high RPM blast!
“Coking” is an issue with high performance DI engines. How big an issue in the Corvette, apparently Rydzewski Assistant Chief Engineer for Small Block V8’s thinks it is enough to discuss the issue in in a magazine article!
Is a “Catch Can” the whole solution? Probably not but it is a help.
Why doesn’t GM install one in the Corvette? Because it requires maintenance and most owners don’t even check oil levels as often as recommended is probably one reason.
Time will tell how much of an issue it is and how much performance will suffer. But in the meantime, it can’t hurt and the oil some folks are finding in their catch cans is sure better collecting in the can than in the intake and baking on the back of the valves! The design and media in a quality catch can condenses oil vapor coming from the PCV system and reduces the amount going into the intake.
They show why you needed gasoline with cleaning additives to avoid “coking.” That was when you were using a carburetor or port injection like all prior Vettes to the C7! There the gasoline goes over the back of the valves. With DI gas squirts directly into the combustion chamber, it never sees the back of the valves. On a high performance engine the valves run hotter and “coking" is more of an issue!
And it’s not like the old days of “blowing it out” with a high rpm run using a rich mixture and turbulence to clean the valves and intake passages! With DI you’re just blowing more air and oil mist from crankcase fumes past the valves!
Disclaimer: I’m not affiliated with a "can" manufacture or care if you buy one or who’s if you do!!
This was with Port Injection! More cleaning additive was helpful. Note DI has no gasoilne passing over the valves!
This is a Shell ad, again only effective with port injection or a carb!
Last edited by JerryU; Jan 30, 2015 at 06:31 PM.
Burning Brakes
Joined: Jul 2011
Posts: 841
Likes: 72
From: NC
The GM rep's comments are interesting. I have no doubt modern engines can and do regularly go over 200,000 miles. But what might be more interesting to know is, when all these cars are serviced regularly, how much money do all the dealerships make from cleaning throttle bodies and other intake components over the life time of all these engines? My guess is that number is substantial.
For those of us that have been around awhile, remember when the PCV hose used to route from one (or both) of the valve covers and clip on to the air filter housing? And remember the oil stain that developed on the air filter and oil funk that used to collect in the bottom of the air filter housing? Just sayin'...
Roll the dice and take your chances.
For those of us that have been around awhile, remember when the PCV hose used to route from one (or both) of the valve covers and clip on to the air filter housing? And remember the oil stain that developed on the air filter and oil funk that used to collect in the bottom of the air filter housing? Just sayin'...
Roll the dice and take your chances.
Last edited by Rave; Jan 30, 2015 at 06:48 PM.
Racer
Joined: Jul 2014
Posts: 285
Likes: 3
From: Disney World Florida
Well, after reading this post today, it reminded me to check my catch can and see what surprise it could be holding. I have not checked the can since I first installed it back 2K miles ago.
Today, the car has 3K miles on it and I was really surprised at what I found. I do not drive the car hard and I have already made the first oil change back at 1K miles.
It appears that this catch can really helps to remove oil that would otherwise enter into the engine.
Check out the pictures taken today in sunny Florida. Peace be with you.
Today, the car has 3K miles on it and I was really surprised at what I found. I do not drive the car hard and I have already made the first oil change back at 1K miles.
It appears that this catch can really helps to remove oil that would otherwise enter into the engine.
Check out the pictures taken today in sunny Florida. Peace be with you.
Last edited by A Solid Rock; Jan 31, 2015 at 08:28 PM.
Drifting
Joined: Aug 2014
Posts: 1,589
Likes: 191
i just ordered my EE catch can today. Non dry sump. I figured it prob isn't necessary, but for $190 and i only have 114 miles on her (picked her up 12/27 and weather horrible in NE) if i put it on soon she will hopefully never see a drop of oil in the intake... I've spent over $3k in mods since ordering her in september, whats another $200??
Instructor
Joined: Nov 2014
Posts: 187
Likes: 10
From: NJ
Looking into things I can do to improve, modify and enhance my car. I have been reading many posts.
My question on Catch Can's - Is the catch can set-up creating or enhancing the environment that will result in additional oils being removed and collecting in the can.
In layman terms is it creating a vacuum so it pulls more oils to collect.
The 2 extremes, instances where no catch can installed, and there is no oil, and those with it installed showing a collection. Granted over filling will cause issues
Just trying to figure it all out, passing the time, waiting on weather that will allow me to drive.
My question on Catch Can's - Is the catch can set-up creating or enhancing the environment that will result in additional oils being removed and collecting in the can.
In layman terms is it creating a vacuum so it pulls more oils to collect.
The 2 extremes, instances where no catch can installed, and there is no oil, and those with it installed showing a collection. Granted over filling will cause issues
Just trying to figure it all out, passing the time, waiting on weather that will allow me to drive.
Burning Brakes
Joined: Jul 2011
Posts: 841
Likes: 72
From: NC
Is the catch can set-up creating or enhancing the environment that will result in additional oils being removed and collecting in the can.
In layman terms is it creating a vacuum so it pulls more oils to collect.
The 2 extremes, instances where no catch can installed, and there is no oil, and those with it installed showing a collection. Granted over filling will cause issues...
In layman terms is it creating a vacuum so it pulls more oils to collect.
The 2 extremes, instances where no catch can installed, and there is no oil, and those with it installed showing a collection. Granted over filling will cause issues...
So far I haven't seen photo's of any DI engines which have a Catch Can that haven't collected at least some level of oil.
Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
I took delivery of my Catch Can the other day (Elite E2 Best). It doesn't create its own vacuum but rather just maintains the engine's vacuum (passing it through). A collection of (what looks like) stainless steel wool in the top of the can helps to collect and condensate the oil vapors, and the oil drips down and collects in the Can.
So far I haven't seen photo's of any DI engines which have a Catch Can that haven't collected at least some level of oil.
So far I haven't seen photo's of any DI engines which have a Catch Can that haven't collected at least some level of oil.
When I opened the C7 after 1000 miles I got one drop.
When I opened the truck after 1000 miles I got a full measuring cup of water/oil.
Based on what some engine builders are saying, some of the C7 blocks have out of round cylinders when they go to machine them....This will definitely contribute to a full catch can.
Pro
Joined: Feb 2015
Posts: 636
Likes: 60
Not only do I agree but a GM enginner with the credentials to be able to speak to the issue did just that in the December 2014 issue of Hot Rod Magazine! They interviewed this GM Engineer who’s title is Assistant Chief Engineer for Small Block V8’s! This is not just any GM spokesman!Here is what this engineer, John Rydzewski, said, paraphrasing:
" A PCV separator, which is unique to the LT4, was developed to keep oily air from being drawn through the intake, where it could end up collecting on the back of the intake valves. A little bit of oil on a port injected engine can help lubricate valves, but because all C7 V8's are direct injected, there's no fuel washing the back of the intake valve. That means oil in the PCV system can end up sticking to the back of the hot valves impeding airflow and eventually preventing the valves from seating properly!”
The intake valves in a high performance engine operate at high temperatures. Ferrari and Porsche have had DI for more years than GM in high performance engines. Read their forums, there are problems with build-up on the intake valves that effects performance, it’s called “coking.” Ferrari was disussing the use of a fluid purge on the intake at each oil change (sounds expensive.). BMW has a mechanical cleaning method to remove "coking" deposits that was shown in a forum thread (very expensive!) Toyota has one DI engine that also has port injection that is activated from time to time to help clean the intake valves! You may remember the gasoline ads that show the extra additives to stop the build-up of baked on carbon on the intake valves on cars with port injection or carburetors. With DI no gasoline goes past them now! No more help if you “blow it out” with a high RPM blast!
“Coking” is an issue with high performance DI engines. How big an issue in the Corvette, apparently Rydzewski Assistant Chief Engineer for Small Block V8’s thinks it is enough to discuss the issue in in a magazine article!
Is a “Catch Can” the whole solution? Probably not but it is a help.
Why doesn’t GM install one in the Corvette? Because it requires maintenance and most owners don’t even check oil levels as often as recommended is probably one reason.
Time will tell how much of an issue it is and how much performance will suffer. But in the meantime, it can’t hurt and the oil some folks are finding in their catch cans is sure better collecting in the can than in the intake and baking on the back of the valves! The design and media in a quality catch can condenses oil vapor coming from the PCV system and reduces the amount going into the intake.
It's not just high-end performance engines with the issue either. VW's and other DI econoboxes suffer the same fate. Nissan likes to use DI engines. I spent 500 bucks at 15k miles to have them perform the "recommended" cleaning on my wife's car. Her maintenance costs run a lot higher than mine do for my port injected Mustang.
Catch cans will slow down the process, but eventually, you'll still have to do the cleaning. Now putting a catch can on a port injected engine? I really see no point.
I think the biggest issue with manufacturers is a: the cost. and B: asking the owner to get under the hood and empty out a catch can once a month or even once a week.
Direct Injection is still a work in progress for all car manufacturers, IMO.
Last edited by CriticalmassGT; Feb 12, 2015 at 11:14 AM.