Catch can, anyone using a catch can on a C3?
Burning Brakes
Joined: Nov 2013
Posts: 889
Likes: 472
From: Central NJ
In high performance engines, such as high compression or forced induction, it's not a good idea to send the crankcase fumes back into the intake.
These engines are run close to the point of detonation. Crankcase gasses/oil are low octane debris that can preignite and cause detonation if sent back into the combustion chamber.
High performance engines are subject to more blow by, not because they are built wrong, but rather because they are built right. Since you need a bigger ring gap for the higher cylinder temperatures you get more blow by. More blow by yields more crankcase gases/oil sent to the valve cover to be exhausted or sucked out using a evac system.
If you have a moderate performance engine with just a small amount of gasses/oil, then a breather is enough.
If you have a really high performance engine, then more oil is blown by and a catch can is useful for keeping the engine bay clean and keeping the oil from getting near your tires.
If you've got build issues and are spewing oil, then a catch can is a stop gap measure until you fix the real issues.
If you have a stockish engine, or need to fulfill emission standards, then feel free to PCV back into the intake.
These engines are run close to the point of detonation. Crankcase gasses/oil are low octane debris that can preignite and cause detonation if sent back into the combustion chamber.
High performance engines are subject to more blow by, not because they are built wrong, but rather because they are built right. Since you need a bigger ring gap for the higher cylinder temperatures you get more blow by. More blow by yields more crankcase gases/oil sent to the valve cover to be exhausted or sucked out using a evac system.
If you have a moderate performance engine with just a small amount of gasses/oil, then a breather is enough.
If you have a really high performance engine, then more oil is blown by and a catch can is useful for keeping the engine bay clean and keeping the oil from getting near your tires.
If you've got build issues and are spewing oil, then a catch can is a stop gap measure until you fix the real issues.
If you have a stockish engine, or need to fulfill emission standards, then feel free to PCV back into the intake.
Drifting
Joined: Apr 2020
Posts: 1,779
Likes: 250
From: Ocean County NJ
If you have a moderate performance engine with just a small amount of gasses/oil, then a breather is enough.
If you have a really high performance engine, then more oil is blown by and a catch can is useful for keeping the engine bay clean and keeping the oil from getting near your tires.
If you've got build issues and are spewing oil, then a catch can is a stop gap measure until you fix the real issues.
If you have a stockish engine, or need to fulfill emission standards, then feel free to PCV back into the intake.
Burning Brakes
Joined: Nov 2013
Posts: 889
Likes: 472
From: Central NJ
Advanced
Joined: Jun 2018
Posts: 81
Likes: 1
I been reading all this about the pcv. I have a problem and I'm not a real knowledgeable mechanic. I know a little. But i have a 454. 10:1 compression. 530HP with edelbrock carb, aluminum heads. Engine has 655 miles on it. I have consumed some oil and my mechanic said that its being pulled through the pcv into the carb and out the exhaust. So he is saying to take out the pcv and put a breather in place and cap off the carb where the hose connects. I have a breather on one side already. I have done that but now have a lot of blow by all over the engine and its also on the windshield. So I'm seeing this about a catch can. Wondering if i need one. Thoughts?
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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2 things, you have a lot of blow by and you should inform your engine builder because it shouldnt be that bad with a new build. The other is a catch can would help solve the mess its making but will not slow down the loss of oil you are experiencing. I too have some oil leaving via the pcv system and my catch can does a great job catching it
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Engines that have not had the rings seat properly will have excessive blowby. How were the rings seated?
Could also be that the baffling inside the valve cover is inadequate. That would allow lots of oil saturated air to escape vs less oil with the air.
To answer your question, yes a catch can in conjunction with the PCV will collect much of your oil. As Rogers said though, it will not solve any excessive blowby issues.
Could also be that the baffling inside the valve cover is inadequate. That would allow lots of oil saturated air to escape vs less oil with the air.
To answer your question, yes a catch can in conjunction with the PCV will collect much of your oil. As Rogers said though, it will not solve any excessive blowby issues.
Last edited by REELAV8R; Oct 5, 2020 at 03:27 PM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
x2 on checking for a proper baffle in the valve cover..use a breather and vent it to the air cleaner
If you got that much blowby on a new build you need to bring it back to him, dont band aid the problem.
Ive always run pvc systems on ds breather on the other never had an issue..stock and strokers that make a lot of rpm
No need for a ricer mod
If you got that much blowby on a new build you need to bring it back to him, dont band aid the problem.
Ive always run pvc systems on ds breather on the other never had an issue..stock and strokers that make a lot of rpm
No need for a ricer mod
