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On a non boosted motor is a catch can really necessary? I know it still catches some oil but wouldn't a old school valve cover filter and plugging the tube be the same? Yes it won't be emissions legal but is there any other benefit of a catch can VS a VC breather?
I would go with a separator and modified PVC system.
Most PVC system replacement valves allow too much vacuum. I would restrict the PVC and run it through a separator (Moroso) . This will keep the vapor level down in the motor, reduce reverse compression (from a pressurized crank case) and keep the Oil cleaner longer.
There are a number of benefits to having a catch can that go beyond just keeping the intake track cleaner.
If you do any racing or a bit of high RPM driving you won't want a old school breather is it will get oil on the valve cover.
I think the biggest benefit to a catch can is that oil mist entering the intake tract can/will affect the octane of the air/fuel mixture contributing to detonation which will cause the computer to pull timing and lose a little power. Extra oil in the combustion mixture will also make the engine run dirtier etc... And, of course the least important benefit is less risk of intake deposits but that is a very minor benefit.
I installed one on my fresh engine this winter...
I don't think a catch can is really 'necessary' but it is beneficial.
Very nice setup Mr D. And your right oil contamination creates all kinds of problems. A functional PCV system is essential to a good running street motor.
No end to the possibilities/combinations though and an owner needs to sort this out for himself. Doing this is a bit of engineering itself. But you have to have the simple big picture here it just uses the low pressure (vacuum) in the intake to draw air from a filtered source through the crankcase then a PCV valve. Common problems are with a poor functioning oil separator in the valve cover that allows to much carry over.
Very nice setup Mr D. And your right oil contamination creates all kinds of problems. A functional PCV system is essential to a good running street motor.
No end to the possibilities/combinations though and an owner needs to sort this out for himself. Doing this is a bit of engineering itself. But you have to have the simple big picture here it just uses the low pressure (vacuum) in the intake to draw air from a filtered source through the crankcase then a PCV valve. Common problems are with a poor functioning oil separator in the valve cover that allows to much carry over.
Good luck and let us know what works for you LT4.
I can't wrap my head around spending > $100 on a catch can.
I think I'm going to make one out of a 3x2 by 5" long aluminum and use either copper or stainless dish scrubbers from Walmart to help the oil mist settle and use a 1/4" clear hose for a sight glass.
Just have to figure out the finer details and put it together OR buy a cheap square one on fleabay for $18 and add the scrubbers to it and the 1/4" clear tubing.
Haven't figured out yet if it's worth my time to build it and tig weld it.
Anymore pictures of your guys setup would be deeply appreciated.
I can't wrap my head around spending > $100 on a catch can.
I think I'm going to make one out of a 3x2 by 5" long aluminum and use either copper or stainless dish scrubbers from Walmart to help the oil mist settle and use a 1/4" clear hose for a sight glass.
Just have to figure out the finer details and put it together OR buy a cheap square one on fleabay for $18 and add the scrubbers to it and the 1/4" clear tubing.
Haven't figured out yet if it's worth my time to build it and tig weld it.
Anymore pictures of your guys setup would be deeply appreciated.
Thanks,
Well are you sure you need a "catch"? Is oil getting by your separators in the valve covers? Or is your PCV valve flowing to much and pulling oil with it?? Lot'a hi-po cars off the showroom these days and none have a catch can as far as I know.
Catch can is a must for all crankcase evacuation system with a vacuum pump or on motors with large amounts of blow-by or positive pressure/supercharged. But on a NA motor it mostly makes up for an ineffective oil separator in the valve cover. Sometimes with new/different rocker arms the splash inside the valve covers changes for the worse.
But a catch can be the trick that works and gives you peace of mind. It just has to seal and resist collapsing under about 20"Hg max. You could probably find something at the dollar store that can work.
I tried the open valve cover vents after seeing what happens to the inside of the engine due to the pcv pulling in oil.
Just the valve cover open filter vents and i get smoke signals out the side of my car when it drips down and hits my headers, and the oil smell when I'm running the car hard.
I picked up a cheap catch can off of amazon, tossed some stainless dish scrubbers in the can, and now i'm trying to figure out where i can mount the thing...
DMITTZ, i like what you did with yours, looks like a nice compact size as well.
Right now i'm looking at where my air pump use to sit since it's a big empty spot, but there sure is not much free space under the hood of a C4!
Look up crankcase evacuation systems they are the most efficient no vapor from the crankcase enters the intake + they pull a slight vacuum in the crankcase. You can build your own system with check valves from the air pump exhaust manifold piping. Kits are available.
A quart paint thinner can, a breather, some hose from the valve covers = a home grown system that works.
'catch can' is thrown around broadly when there is a matrix of actual capabilities and limitations across the different brands and quality levels. they do not all perform or even 'do' the same thing.
Start with learning what you currently have, and then decide what part of that system you need to improve, what parts you like, what sacrifices you can make, and what you cannot live without.
typically valve cover breathers are more messy, will smell more, and will partially or completely defeat a pcv system if used in combination, but they do have some nice applications when considered carefully.
open breathers are a fix for a crankcase pressure issue, not a pcv system issue
closed catch cans are a fix for a pcv issue, not a crankcase pressure issue
finding one system that does both is the real trick
I have some more information on my website and video channel.
'catch can' is thrown around broadly when there is a matrix of actual capabilities and limitations across the different brands and quality levels. they do not all perform or even 'do' the same thing.
Start with learning what you currently have, and then decide what part of that system you need to improve, what parts you like, what sacrifices you can make, and what you cannot live without.
typically valve cover breathers are more messy, will smell more, and will partially or completely defeat a pcv system if used in combination, but they do have some nice applications when considered carefully.
open breathers are a fix for a crankcase pressure issue, not a pcv system issue
closed catch cans are a fix for a pcv issue, not a crankcase pressure issue
finding one system that does both is the real trick
I have some more information on my website and video channel.
If you have a link, i would like to learn more!
02-23-2017, 05:08 PM
Catch can VS valve cover breather
