Do you need a catch can?
Race Director
Joined: Jan 2014
Posts: 10,709
Likes: 7,100
From: Fulshear, TX
I can't remember the name of the website I found last night, but now I just found it for $226 from some no-name site called AutoTalent using their promo code. Do a Google search for "Mishimoto C8 Corvette catch can" and you'll see a bunch of results. They're all going to just be drop-shippers that basically do nothing more than process your payment. Use a credit card you trust and should be nothing to worry about. I was able to get my Eibach rear swaybar this way and it came directly from Eibach's warehouse in CA.
Burning Brakes
Joined: Nov 2022
Posts: 1,047
Likes: 1,108
From: Western Mass
"The engineers for this motor said it is not needed. If you don't trust them, then why would you buy the car that they designed?"....
And they designed the DCT too.... engineers don't solely design cars. Marketing and Accounting have a lot of input. Sometimes too much. Spent a lot of years in engineering in the aerospace business. Sadly, sometimes suboptimal designs were put into service due to competing priorities. Sometimes it didn't matter, sometimes it mattered a lot. And by a lot I mean losing out on a $3B aircraft opportunity.
So.... I'll decide what is "needed" or not and do the best I can to keep the car happy. And me too.
And they designed the DCT too.... engineers don't solely design cars. Marketing and Accounting have a lot of input. Sometimes too much. Spent a lot of years in engineering in the aerospace business. Sadly, sometimes suboptimal designs were put into service due to competing priorities. Sometimes it didn't matter, sometimes it mattered a lot. And by a lot I mean losing out on a $3B aircraft opportunity.
So.... I'll decide what is "needed" or not and do the best I can to keep the car happy. And me too.
Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
"The engineers for this motor said it is not needed. If you don't trust them, then why would you buy the car that they designed?"....
And they designed the DCT too.... engineers don't solely design cars. Marketing and Accounting have a lot of input. Sometimes too much. Spent a lot of years in engineering in the aerospace business. Sadly, sometimes suboptimal designs were put into service due to competing priorities. Sometimes it didn't matter, sometimes it mattered a lot. And by a lot I mean losing out on a $3B aircraft opportunity.
So.... I'll decide what is "needed" or not and do the best I can to keep the car happy. And me too.
And they designed the DCT too.... engineers don't solely design cars. Marketing and Accounting have a lot of input. Sometimes too much. Spent a lot of years in engineering in the aerospace business. Sadly, sometimes suboptimal designs were put into service due to competing priorities. Sometimes it didn't matter, sometimes it mattered a lot. And by a lot I mean losing out on a $3B aircraft opportunity.
So.... I'll decide what is "needed" or not and do the best I can to keep the car happy. And me too.
Burning Brakes
Joined: Nov 2022
Posts: 1,047
Likes: 1,108
From: Western Mass
Sure, Tremec designed the DCT….with GM…. And to price targets like all major subs.
I’m tracking my car and will report back on how much or little oil is in the can after the days tracking
I’m tracking my car and will report back on how much or little oil is in the can after the days tracking
Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
1) Does using a catch can INCREASE the amount of oil, due to changes in pressure to the PCV system, the lower velocity of the air flow allowing more oil vapor to cool and condensate into droplets, etc...
2) Does the current OEM solution actually lead to PROBLEMS. Just because we captured some oil, doesn't mean that that oil would cause issues.
The answers appear to be, "possibly" for #1, and "no, not really" for #2...
Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
Well, the second part is kinda easy... Are there reports of valve issues related to excessive carbon buildup from the PCV system. As yet, there are none. There are a lot of people in these and other forums... if some folks were seeing this with the C8, I can't imagine that the owners would have kept that to themselves...
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Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
There are plenty of GM fleet vehicles with GDI motors and millions of them are over 100k in miles over their lifetimes and it doesn't seem to be a big issue.
It's like when some guys get a new Glock. They have to go in and upgrade this and upgrade that, because the steel guide rod doesn't flex like the factory plastic one does, and they dump all sorts of "upgrades" in it, meanwhile the stock ones don't seem to have issues and they pass insane torture tests without breaking a sweat...
The aftermarket is very good at marketing... And preying on the fear that your $80k-$120k car, your pride and joy, will grenade if you don't buy their $200 product, manages to convince a lot of people, who then evangelize the product in order to justify buying it... Meanwhile, I can't find a SINGLE report of an LT2 motor having issues in this area after nearly half a decade... SMH.
Race Director
Joined: Aug 2016
Posts: 12,712
Likes: 10,140
From: Garden Valley CA
The LT1 and LT4 engines used both in the C7 and Camaro should be representative of the C8 LT2 with respect to valve coking. The LT1 has been out for a decade now. If there were problems with valve coking I can't imagine there wouldn't be at least some postings by now.
Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
Exactly. I have seen a couple pics of some dirty valves, but no reports of it seeming to be a problem, other than visually people not liking it...
Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
But if it doesn't hurt it... does it matter?
I mean, that is the main topic for this thread... the car NEEDING it or not... Not personal preferences or theories... Is there an actual documented problem, and does the catch can reduce or eliminate it?
So far, the internet and fleet data says no, to both...
I mean, that is the main topic for this thread... the car NEEDING it or not... Not personal preferences or theories... Is there an actual documented problem, and does the catch can reduce or eliminate it?
So far, the internet and fleet data says no, to both...
Drifting
Joined: Mar 2016
Posts: 1,731
Likes: 496
From: Glenelg MD
So, anyone who uses the argument that a can increases the oil isn't thinking beyond their own nose.
Race Director
Joined: Jan 2014
Posts: 10,709
Likes: 7,100
From: Fulshear, TX
No.
To fix the portion in red, the port in question here goes directly into the intake manifold downstream from the throttle body. The port upstream of the throttle body in the intake tube is clean with zero oil residue found. Mishimoto confirmed this during their R&D testing and it matches my personal findings after doing multiple intakes/throttle bodies/intake manifolds on C8 Corvettes.
Catch cans (in general) can't change the (overall) pressure in a system. They have no active parts, and even the ones with "filters" in them are so free flowing as to provide practically zero restriction... the thin tubing connecting all of the PCV system components would probably be more restrictive. Pressure may be instantaneously reduced at the inlet side as the small pipe goes into a large can, but that pressure has to kick right back up when it hits the exhaust side of the can. The key point being... none of this can introduce more oil into the system, but a (even temporary) reduction in pressure can allow for more of what does exist to condense out. That's a good thing as the entire point of the can is to remove as much oil (and other vapors) from the system as possible before it gets reintroduced ahead of the throttle body.
So, anyone who uses the argument that a can increases the oil isn't thinking beyond their own nose.
So, anyone who uses the argument that a can increases the oil isn't thinking beyond their own nose.
Drifting
Joined: Mar 2016
Posts: 1,731
Likes: 496
From: Glenelg MD
Associated questions that might temper the view of your question's response would be how many miles do those cars see in their lifetime? When are the cars removed (permanently) from service (e.g., are they still using 10-year old C7s, or have they been retired now that C8s are out)? Are teardowns done of those engines after the car is retired?
Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
Catch cans (in general) can't change the (overall) pressure in a system. They have no active parts, and even the ones with "filters" in them are so free flowing as to provide practically zero restriction... the thin tubing connecting all of the PCV system components would probably be more restrictive. Pressure may be instantaneously reduced at the inlet side as the small pipe goes into a large can, but that pressure has to kick right back up when it hits the exhaust side of the can. The key point being... none of this can introduce more oil into the system, but a (even temporary) reduction in pressure can allow for more of what does exist to condense out. That's a good thing as the entire point of the can is to remove as much oil (and other vapors) from the system as possible before it gets reintroduced ahead of the throttle body.
So, anyone who uses the argument that a can increases the oil isn't thinking beyond their own nose.
So, anyone who uses the argument that a can increases the oil isn't thinking beyond their own nose.
We can debate back and forth why each of us THINKS what we think, but at the end of the day there are two things that can't really be argued... 1) Corvette Engineers said flat out, not a problem, they designed all this into the motor itself, and 2) there do not appear to be ANY instances or data of whatever oil goes into the motor, causing any issues.
When you look at the oil captured after 1000 miles, its like, WOW, look, its several table spoons!
Which means that for every 10 miles, there might be 1 DROP of oil entering the intake manifold... It just isn't enough to be worried about, and after all these years, if valves were failing or acting up because of this, we would know. So we can argue about why we think it WOULD be a problem, but the facts appear to be that it just isn't...