MotorWeek - Goss' Garage: Need For Catch Can/Oil Separator on GDI Engines
07-09-2016, 07:22 PM
#1
Le Mans Master
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MotorWeek - Goss' Garage: Need For Catch Can/Oil Separator on GDI Engines
This week's Motor Week episode (S35 E44) Goss' Garage did a segment on the need for Catch Can/Oil Separator on GDI engines. Appears many in the industry are finally coming to grips with carbon build-up on intake valves associated with GDI engines.
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07-09-2016, 10:33 PM
#3
Team Owner
I wish GM would come out with a definitive "yes" or "no" as to whether or not C7 owners should install a catch can.
07-09-2016, 10:34 PM
#4
Drifting
Originally Posted by themonk
I wish GM would come out with a definitive "yes" or "no" as to whether or not C7 owners should install a catch can.
07-09-2016, 10:59 PM
#5
E-Ray, 3LZ, ZER, LIFT
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07-09-2016, 11:11 PM
#6
E-Ray, 3LZ, ZER, LIFT
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Also what would folks do with the 3 or 4 ounces of oil collected? Put it down the drain? Doubt many folks would bring 3 ounces to a recycle center! I put mine in a 12 quart oil collection container I use when I change oil and dump it at the recycle center when I change oil.
Can't see GM can telling folks, yep collecting that oil will reduce deposits on the intake valves that we're all getting with DI engines! That is all but Toyota on one engine that uses DI and periodically port injection that cleans the valves! Someone indicated port injection is actually better at idle!(?)
07-09-2016, 11:52 PM
#7
Team Owner
GM or any manufacturer cannot tell you to add something that requires removing oil from the "can" periodically! Many folks don't even check their oil level when recommended. If you let the can fill up you would cause problems, the PCV system would be blocked!
Also what would folks do with the 3 or 4 ounces of oil collected? Put it down the drain? Doubt many folks would bring 3 ounces to a recycle center! I put mine in a 12 quart oil collection container I use when I change oil and dump it at the recycle center when I change oil.
Can't see GM can telling folks, yep collecting that oil will reduce deposits on the intake valves that we're all getting with DI engines! That is all but Toyota on one engine that uses DI and periodically port injection that cleans the valves! Someone indicated port injection is actually better at idle!(?)
Also what would folks do with the 3 or 4 ounces of oil collected? Put it down the drain? Doubt many folks would bring 3 ounces to a recycle center! I put mine in a 12 quart oil collection container I use when I change oil and dump it at the recycle center when I change oil.
Can't see GM can telling folks, yep collecting that oil will reduce deposits on the intake valves that we're all getting with DI engines! That is all but Toyota on one engine that uses DI and periodically port injection that cleans the valves! Someone indicated port injection is actually better at idle!(?)
07-10-2016, 01:05 AM
#8
Pro
I saw this episode a while back. Decent explanation for the layman. It's clear this is an issue. Even GM folks I spoke with at the Bash a few months ago agreed it's a known issue. This is perhaps why there is a PCV re-route in the new GS (and I'm assuming other dry-sump 2017 C7s).
Still, like the cooling issue on the Z06, however GM addresses it, I doubt they will issue any press releases or otherwise make a big deal of it.
Still, like the cooling issue on the Z06, however GM addresses it, I doubt they will issue any press releases or otherwise make a big deal of it.
07-10-2016, 06:59 AM
#9
Le Mans Master
07-10-2016, 07:24 AM
#10
Melting Slicks
That was a Gen V 1LE (LS3) and last I checked he was lawyering up as its complete ********
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07-10-2016, 07:35 AM
#11
Melting Slicks
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In a recent Ask Tadge, he told us up front that a catch can will void the warranty. I was going to add one but now not sure. I guess you could keep any removed parts and restore the car to original before taking it to a dealer. Unless, of course, your failure required a rollback ride to the dealer in which case you won't have an opportunity to restore the car back to original.
07-10-2016, 08:41 AM
#12
They are not going to want the masses installing aftermarket parts.
07-10-2016, 08:45 AM
#13
07-10-2016, 10:32 AM
#14
E-Ray, 3LZ, ZER, LIFT
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Yep, see a repost I put in below.
Your mixing apples and oranges. The Carmaro has a different PCV system and perhaps a catch can does not work as simply as it does in the C7. Your car do as you wish.
This is Tadges answer as why the C7 doesn't have the Camaro "Catch can," which he says is not a catch can:
"Tadge answered:
To answer the second question first: No, the 2017 Corvette LT1 will not have the Camaro V8 PCV air/oil separator (what the questioner calls a "catch can") added to its oil management system. For those not familiar with the abbreviation PCV, it stands for "positive crankcase ventilation"
Even though the Corvette and Camaro share the LT1, they are very different in execution detail. The LT1 in the Corvette sits lower and very close to the ground to enable an industry-leading low profile hood and good sight lines despite a very low seated position. Having the engine close to the ground is great for keeping the vehicle's center of gravity down, but means the oil pan is relatively shallow. Having little depth in the oil pan means it is very challenging to scavenge oil in high G loading conditions. For this reason we add dry sump lubrication to our high performance models. The Camaro's higher engine position allows for a deeper oil pan and a reliable configuration for picking up oil for delivery to all parts of the engine. Thus the Camaro is able to avoid the cost and mass of the dry sump tank and resulting complexity of the lube system.
The Corvette's dry sump tank looks relatively simple on the outside but the internals are really quite complex. The top third of the tank contains a PCV air/oil separation system. On the Corvette, PCV lines route from the valve covers to the air/oil separator on top of our dry sump tank. Oil from PCV air is separated and returned to the lube system through the oil tank. The PCV separation system on Camaro V8 performs a similar function except oil is returned to the engine oil pan from the PCV separator's drain back tube. The Camaro V8 PCV air/oil separator is more complex than a "catch-can" since it not only separates oil from PCV air it provides a drain back path for this oil to be reused by the lube system. "Catch-can" systems that do not have a drain back path for separated oil run the risk of poor oil pressure performance over time as oil is removed from the lube system.
The bottom line is that both cars use optimized engineering solutions for their lube systems based on vehicle architectural considerations."
In a recent Ask Tadge, he told us up front that a catch can will void the warranty. I was going to add one but now not sure. I guess you could keep any removed parts and restore the car to original before taking it to a dealer. Unless, of course, your failure required a rollback ride to the dealer in which case you won't have an opportunity to restore the car back to original.
Tadge said, see below, "Catch-can" systems that do not have a drain back path for separated oil run the risk of poor oil pressure performance over time as oil is removed from the lube system."
As I mentioned above IF you don't empty the catch can it can fill with oil and then block the PCV crackcase to intake manifold passage. That is one reason GM doesn't "endorse catch cans, IMO. Perhaps he meant if you drain too much oil out of the system with the catch can and don't check the level you'll have low oil pressure! He didn't elaborate. Many folks don't even check their oil level per the manual let alone empty a catch can of oil. It you look at where it is, at least in my Z51, it is just in the PCV line from crackcase to manifold. It catches oil mist and drops, condenses them in stainless ribbon and they fall to the bottom of the tank. No restrictions no blocking IF you empty the oil. the bottom of the tank is about 4 inches from the inlet and outlet lines. It can hold quite a bit of oil before blocking would occur.
If your unsure don't add one. My expedience with GM warranty issues is logic prevails and I would defend what I have added but it will not be needed, IMO.
Tadge said, see below, "Catch-can" systems that do not have a drain back path for separated oil run the risk of poor oil pressure performance over time as oil is removed from the lube system."
As I mentioned above IF you don't empty the catch can it can fill with oil and then block the PCV crackcase to intake manifold passage. That is one reason GM doesn't "endorse catch cans, IMO. Perhaps he meant if you drain too much oil out of the system with the catch can and don't check the level you'll have low oil pressure! He didn't elaborate. Many folks don't even check their oil level per the manual let alone empty a catch can of oil. It you look at where it is, at least in my Z51, it is just in the PCV line from crackcase to manifold. It catches oil mist and drops, condenses them in stainless ribbon and they fall to the bottom of the tank. No restrictions no blocking IF you empty the oil. the bottom of the tank is about 4 inches from the inlet and outlet lines. It can hold quite a bit of oil before blocking would occur.
If your unsure don't add one. My expedience with GM warranty issues is logic prevails and I would defend what I have added but it will not be needed, IMO.
"Tadge answered:
To answer the second question first: No, the 2017 Corvette LT1 will not have the Camaro V8 PCV air/oil separator (what the questioner calls a "catch can") added to its oil management system. For those not familiar with the abbreviation PCV, it stands for "positive crankcase ventilation"
Even though the Corvette and Camaro share the LT1, they are very different in execution detail. The LT1 in the Corvette sits lower and very close to the ground to enable an industry-leading low profile hood and good sight lines despite a very low seated position. Having the engine close to the ground is great for keeping the vehicle's center of gravity down, but means the oil pan is relatively shallow. Having little depth in the oil pan means it is very challenging to scavenge oil in high G loading conditions. For this reason we add dry sump lubrication to our high performance models. The Camaro's higher engine position allows for a deeper oil pan and a reliable configuration for picking up oil for delivery to all parts of the engine. Thus the Camaro is able to avoid the cost and mass of the dry sump tank and resulting complexity of the lube system.
The Corvette's dry sump tank looks relatively simple on the outside but the internals are really quite complex. The top third of the tank contains a PCV air/oil separation system. On the Corvette, PCV lines route from the valve covers to the air/oil separator on top of our dry sump tank. Oil from PCV air is separated and returned to the lube system through the oil tank. The PCV separation system on Camaro V8 performs a similar function except oil is returned to the engine oil pan from the PCV separator's drain back tube. The Camaro V8 PCV air/oil separator is more complex than a "catch-can" since it not only separates oil from PCV air it provides a drain back path for this oil to be reused by the lube system. "Catch-can" systems that do not have a drain back path for separated oil run the risk of poor oil pressure performance over time as oil is removed from the lube system.
The bottom line is that both cars use optimized engineering solutions for their lube systems based on vehicle architectural considerations."
Last edited by JerryU; 07-10-2016 at 10:36 AM.
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07-10-2016, 10:45 AM
#15
E-Ray, 3LZ, ZER, LIFT
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I watched that video again Goss does not mention a dry sump!?? He also says a Catch Can can "virtually eliminates" the coking issue (he doesn't use the word coking but that is what he means.) Guess I question the virtually eliminate as some vapor will go thru the can, but it's certainly a help! He ususally has good advise.
07-10-2016, 11:06 AM
#16
I watched that video again Goss does not mention a dry sump!?? He also says a Catch Can can "virtually eliminates" the coking issue (he doesn't use the word coking but that is what he means.) Guess I question the virtually eliminate as some vapor will go thru the can, but it's certainly a help! He ususally has good advise.
07-10-2016, 11:45 AM
#17
E-Ray, 3LZ, ZER, LIFT
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Sorry thought you were referring to the Goss video. 
A dry sump has a lower pressure in the crankcase and some oil fumes will be picked up by the scavenge pump. Have no idea of what percentage.
However my catch can is in the PCV line from the crackcase to the intake manifold. I have only one input and one outlet that just sits in the exact same line I removed. I get oil in my dry sump catch can. It's oil that is not going into the intake and baking on the backs of the intake vales and valve steams!
Don't see how anyone can say it is not needed or provides no help!
A dry sump has a lower pressure in the crankcase and some oil fumes will be picked up by the scavenge pump. Have no idea of what percentage.
However my catch can is in the PCV line from the crackcase to the intake manifold. I have only one input and one outlet that just sits in the exact same line I removed. I get oil in my dry sump catch can. It's oil that is not going into the intake and baking on the backs of the intake vales and valve steams!
Don't see how anyone can say it is not needed or provides no help!
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Maxie2U (07-10-2016)
07-10-2016, 01:05 PM
#19
Le Mans Master
Note to Self: Don't install unnecessary items on engine like a "Catch Can".
"We intently looked for unusual deposit formation during the entire Gen 5 Small Block development phase (4 years) as well as the 200,000 mile in-vehicle long term testing. We have not seen anything unusual and zero performance degradation." Tadge Juechter
07-10-2016, 01:07 PM
#20
Melting Slicks
Note to Self: Don't install unnecessary items on engine like a "Catch Can".
"We intently looked for unusual deposit formation during the entire Gen 5 Small Block development phase (4 years) as well as the 200,000 mile in-vehicle long term testing. We have not seen anything unusual and zero performance degradation." Tadge Juechter
"We intently looked for unusual deposit formation during the entire Gen 5 Small Block development phase (4 years) as well as the 200,000 mile in-vehicle long term testing. We have not seen anything unusual and zero performance degradation." Tadge Juechter
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sam90lx (07-11-2016)