C8 Catch Can Controversy
#1
Racer
Thread Starter
C8 Catch Can Controversy
Last November, one of the first things I did after picking up my 2022 HTC was to install a UPR Products catch can. Very soon afterwards I read they weren't needed on a C8 and were a waste of money. Fast forward 6500 miles and you can see the amount of oil in the can. Admittedly not much. I would guess about one third of what was deposited in my C7 GS. Is it worth the money? I don't know. You be the judge.
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CorvetteBrent (07-15-2022)
#2
Engineers who designed the engine and GM that warranties the engine don’t think a catch can is needed.
The engineers know a whole lot more about engines than I do; GM sure doesn’t want to pay for warranty work.
I will trust their collective judgement.
Cheers!
The engineers know a whole lot more about engines than I do; GM sure doesn’t want to pay for warranty work.
I will trust their collective judgement.
Cheers!
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#4
GM only needs the engine to operate for 5 years. After that you're on your own. Any oil in the catch can didn't coat the MAF or the intake valves.
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#5
Race Director
If you did road course events you would have 4oz.+ per day with the full throttle, compression braking, full throttle cycling. I would get that much (what your picture showed) in 2000-3000- miles of highway driving, but 4 oz. each track day in my LS7, stock or full HCI. Only in road course driving does any real amount of oil go thru the PCV system if the engine is working right.
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MikeinAZ (07-14-2022)
#6
Le Mans Master
Blow-by oil, catch-can or not, will never coat the MAF due to the C8's plumbing. If you get a film of oil on your C8's MAF it is from an over-oiled aftermarket cotton gauze air filter.
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hamta (07-12-2022)
#7
Le Mans Master
The big save a catch can does is the oil deposits that turn to carbon buildup on the intake valves. The factory engineering isn’t too concerned about this BC there are maintenance procedures to fix this, albeit incredibly expensive. Still the factory won’t be concerned
I would be on the fence installing one on an NA engine. Boosted is an entirely different situation. When I boosted my C6 it was foolish not to go with a catch can.
I would be on the fence installing one on an NA engine. Boosted is an entirely different situation. When I boosted my C6 it was foolish not to go with a catch can.
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CorvetteBrent (07-15-2022)
#8
Do they add catch cans on the cars at the Ron Fellows school?
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#9
Burning Brakes
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The GM engineers answered this in an interview a while back. The way their dry sump system works that oil would have made it back into the sump not the cylinders.
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#10
Melting Slicks
It may not need one but it won't hurt. GM is a bean counting company which is why it isn't there factory just like a manual way to access the rear hatch
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Maxie2U (07-12-2022)
#11
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No. The cars are totally stock.
I might add that adding a catch can on an otherwise stock engine is at best unnecessary and at worst detrimental.
I might add that adding a catch can on an otherwise stock engine is at best unnecessary and at worst detrimental.
Last edited by Chemdawg99; 07-13-2022 at 08:13 AM. Reason: Grammar correction
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#12
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Do an "Advanced search" across ANY series Vette Forums here from at least the C5 on and you will find many, many threads touting or criticizing catch cans. If it were so simple and so great, not to mention remotely necessary, one would think by now (only my opinion as a life-long scientist) even GM... and, all the other manufacturers... would have figured it out.
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#13
Race Director
Per my post #5 above, I would say it is only necessary if you do road courses and run at a high level.
#14
Le Mans Master
I’m a big fan of UPR Products their CC design and quality is 2nd to no one. I had one installed on my C7 and it caught a lot of gunk and the outer tips never got black even after 6500 mile road trips. I installed UPR’s C8 CC right after I took delivery in April so time will tell if it’s needed on my C8.
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blkvett01 (07-13-2022)
#15
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I had a catch can on my C5 and also have one on my C7. It does catch some oil in the can and I figure it keep the oil out of the intake. There are arguments for and against catch cans on the Corvettes - I simply chose to go with the catch can on my cars.
#16
Le Mans Master
Do AMG, McLaren, Ferrari, Lamborghini, and Pagani have catch cans?
#18
Melting Slicks
This is not always true. Moving air molecules costs energy. The energy has to come from somewhere.
if you add a longer line into the pcv system or additional volume, you add air molecules, now you need more energy to move more mass of air.
The increased demand for energy results with higher pressure, if the same energy is being input as before the added volume.
This increased pressure results with more oil being blown from an engine- the can volume causing oil to blow out of the engine, impacting PCV performance.
In other words: Just because you catch oil in the can, doesn't mean the oil would have been there without the can.
I am not against catch devices. But like most modifications, there is a right way and wrong way to do them.
In the case of catch cans, you MUST measure the crankcase pressure before, and after the installation, and then take steps to ensure the previous pressure inside the crankcase as before the install is being met.
Adding a catch can is like adding a fuel regulator or a supercharger or any other mod: you must set the pressure properly once install is complete.
If you install a new fuel regulator, you don't just blindly assume the fuel pressure is correct.
IF you install a supercharger, you don't blindly assume the boost pressure is correct.
If you install new tires, new oil pump, new transmission, you don't blindly assume the pressure is correct.
The same goes for catch can. You must measure crankcase pressure and set it after the install as with all other pressure scalar.
A catch device can assist with oil aspirate during a true thrashing on a track specific vehicle without appropriate dry sump system configuration, typically wet sump applications with inadequate drainage of the head for example, may require some type of can device, those are the rare situations where it may be helpful, and it must be installed properly as with all modifications.
if you add a longer line into the pcv system or additional volume, you add air molecules, now you need more energy to move more mass of air.
The increased demand for energy results with higher pressure, if the same energy is being input as before the added volume.
This increased pressure results with more oil being blown from an engine- the can volume causing oil to blow out of the engine, impacting PCV performance.
In other words: Just because you catch oil in the can, doesn't mean the oil would have been there without the can.
I am not against catch devices. But like most modifications, there is a right way and wrong way to do them.
In the case of catch cans, you MUST measure the crankcase pressure before, and after the installation, and then take steps to ensure the previous pressure inside the crankcase as before the install is being met.
Adding a catch can is like adding a fuel regulator or a supercharger or any other mod: you must set the pressure properly once install is complete.
If you install a new fuel regulator, you don't just blindly assume the fuel pressure is correct.
IF you install a supercharger, you don't blindly assume the boost pressure is correct.
If you install new tires, new oil pump, new transmission, you don't blindly assume the pressure is correct.
The same goes for catch can. You must measure crankcase pressure and set it after the install as with all other pressure scalar.
A catch device can assist with oil aspirate during a true thrashing on a track specific vehicle without appropriate dry sump system configuration, typically wet sump applications with inadequate drainage of the head for example, may require some type of can device, those are the rare situations where it may be helpful, and it must be installed properly as with all modifications.
#19
#20
This is what I thought as well. But, I reviewed the crankcase ventilation description and circuits in the service manual, and the instructions for installing the UPR catch can, and its not clear why that statement is true. There are three separate "tubes" involved. 1) filtered fresh air is routed from upstream of the throttle plate through a formed nylon fresh air tube to PCV fittings in the left and right rocker arm covers. The rocker arm cover design shields rocker arm oil spray, to reduce the potential for oil being drawn back into the fresh air PCV tube during any backflow of the ventilation system. 2) Separated foul vapor from the engine oil tank is routed to PVC fittings in the left and right rocker arm covers via a formed nylon recirculation tube. 3) Foul crankcase vapor is routed through a formed nylon foul air tube on the engine oil separator in the engine valley to right side rear of the intake manifold. From the UPR instructions, the catch can is installed in this third path - the original tube is removed and replaced by a tube from the "engine valley" (essentially the crankcase) to the catch can, and another tube from the catch can to the right side of the intake manifold. It does not seem possible for any oil in this path to go anywhere other than to intake manifold, or the catch can if one is installed. So, in the context of the engineer's statement, this path must be completely free of oil. But with the catch can installed, oil is collected. The only thing I can think is the theory that without the catch can there is no oil in that path, and the presence of the catch can somehow changes the pressure in the line and allows oil to enter it. That seem questionable - if anything the extra tubing and catch can would reduce the flow though that line - why would that cause more oil to enter it? Did the engineers elaborate on their explanation of why "that oil would make its way back to the oil sump"?
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SECLT22021 (07-13-2022)