Just curious who is running catch cans , what kind and how much you collect over X miles. I’ve been running one since I put on new heads and collect about 4 to 5 oz of oil every three thousand miles. Just pure oil it appears, no real moisture content.
Pretty polarized opinions on this subject when I do a search on it. Though I’d see what C3 guys think about it, particularly ones who have modified engines.

 

Sounds normal for a engine in good working order. Catch cans are a must have item on LS engines to keep that from going through the intake.

 

Until two years ago I never even knew they existed. I've become aware of them through a 6th generation Mustang forum. As you already know historically the PCV system would circulate oil vapors, and I guess some oil, back into the intake manifold where it would burn up in the cylinders. Any oil that landed on an intake valve would be washed away by the incoming air fuel mixture. With the advent of direct fuel injection no gasoline is present to wash away the oil so carbon deposits can build up on the intake valves. So I'm not clear as to what benefit it provides for a carbureted or non-direct fuel injection engine. Can you explain your reasons for thinking it is beneficial and what is different in an LS engine?

 

The oil mist is what you are catching with the catch can. The water vapor is burned. It's just a condenser/separator. I put one on my supercharged LS3 and it did pull out oil mist from the PCV system before it could be burned in the combustion process BUT it was noisy at idle, so I gave up on it and pulled it off. It would gurgle a lot and I could not handle the sound. Just a bad design in my opinion. They seem to cost a lot for what you get so I have not been in a hurry to try another one.

 

On newer cars I always use them to keep the intake clean as no fuel washes the oil down. Anything before the injector is just coated with oil.

On my carbureted C3 I don't as fuel cleans the whole intake manifold.

 

Oil doesn’t just coat intake valves. It burns during combustion. It coats exhaust valves ,piston top and lowers octane in the chamber. Carbon deposits in the rings, on the plugs. How much is dependent on varying conditions.
ideally if the combustion temps were high enough via perfect jetting, it would probably burn off pretty cleanly. But in the carb world you can’t maintain perfect jetting due to constantly changing conditions....so , catch can.

 

I don't use one and I removed my pcv. Just use two breather caps. No oil misting in engine compartment or contaminants entering the combustion chamber. No leaking seals either. Running this way for years. My other vehicles are newer and I leave them as is from the factory.

 

On the other side of the coin, what makes a good catch can? I did some research last winter and liked the blue one on Amazon. (price & design)

Obviously you want an air tight seal / gasket.
Maybe a choice of two sizes of hose barbs.
A good mounting bracket.
And some type of screen or separator in the base.

Some had dipsticks to check depth of fluid in can. Some had air filter baffle on top.
But none appeared to have a decent drain. I would not want a big job to remove the unit and empty it.
I have looked at installing a petcock on the unit. Maybe even a drain hose? IDK

 

Seems like the more expensive ones have multiple chambers, baffles and a fine micron filter before returning to the engine. I'm not convinced that $300 is a reasonable price for one though, I guess it depends on what your protecting. Boosted power and it's probably more critical to keep oil out of the turbo/super charger and intercooler.

Mine has a baffle and an open can, no multiple chambers (cheaper). It also has the dipstick. I put a scotch brite pad in the bottom for condensing media for the oil mist.

 

I have one on my swap. LS1 with an inline PCV. Checked last night after about 800 miles of driving. Hardly a drop. It has a bottom petcock like a radiator petcock so it's easy to check. My LS1 is built with hone to fit Diamond forged pistons and AFR heads. Also a great 91 octane tune. Runs great. Don't know if that makes difference but for me the catch can wasn't worth much. It wasn't $300 but recommended by the LS Tech guys. Don't recall the brand. It has a filter internally.

 

I was searching along the lines of $35-$40 for a can, plus plumbing cost. In laymans terms: el-cheapo. Then if it didn't work out, I 'm not out much.

I like the idea of a plastic sponge in the bottom. Some product reviewers suggested steel-wool to trap oil. Don't like the thought of tiny pieces of steel getting sucked into you know where.

 

The good cans uses a SS that looks like this.

 

They need to be able to give off heat. Need to condense vapors. If it is bad at heat conduction it will not stop much.

 

I used the stainless scrubber , it’s pretty robust so I’m not concerned with any breaking off and getting sucked up.

 

Your basic puke tank.

 

The Catch cans that we have heard so much about recently are more important on the newer Gasoline Direct Injection systems where the fuel is under a higher pressure and injected directly into the cylinder at precisely the right time just like a diesel in a lot of ways.

From the reading I have done the catch cans is supposed to stop nasty oil substances from getting burned inside your engine. On cars with GDI we have been seeing some nasty contaminants in the catch cans. My daughter has a 2011 Camaro with the GDI 3.6 L V-6 in it and that engine will need one.

Carbureted cars wash all their intake parts internally when they run. EFI and sequential port wash their parts to some degree. An engine with GDI will not introduce the fuel cleaning elements until combustion takes place and then it is a bit late. Valve stems from carbureted cars have little to no real build-up on the valve stem. Stronger detergents were introduced long ago to prevent valve stem build-up but they work by washing over the valve stem on the way to the cylinder. This newer GDI system has nothing but air or exhaust blowing over the stems The GDI cars are starting to see some problems with unburned junk sticking to parts and have required some manufacturers to de-carbonize the cylinders to get rid of the newer deposits. The idea of the Catch can was to intercept the material that makes the deposits on the valve stem and other places. There are already special cleaners out there just for GDI engines so controlling the problem is not as bad as it was initially.

On my C3 with its 427 I still use a PCV on my valve covers. I like to see the nasty blow by get burned in a car like mine as it runs rich and has a big carburetor. Having a vacuum in your engine will help the rings seat and stay sealed up the best they can.

Best regards,
Chris

 

I use one because I like to keep oil out of my cylinders. I have a moroso one when I used the air breather as an intake filter. I stopped that and added a summit separator that acts as a vent and an intake under high vacuum

This is the summit can

This is the moroso. I've caught some oil in it but never measured it. I good couple of ounces every so often. It goes through a PCV valve in the fill tube

 

ctmccloskey,

Keep in mind that the engines of this century have tighter clearances between piston oil rings and the cyl walls. The older style had more room which created blow-by.

A concern to me to run a oil catch can would not be so much for what goes into the cylinder, but rather to extract the moisture, contaminates, fuel droplets in the crankcase.

Some people run twin valve cover open style breathers. And that's fine, been there. That lets crankcase pressure out, but does almost nothing as far removal of contaminates, which needs a vacuum source (PCV) to work.

 

4 to 5 ounces of oil every 3000 miles seems like a bit much to me. I have a Billet Specialties PCV breather thingy on the valve cover. I was noticing how wet with oil the hose was where it goes into the PCV nipple on the carb, so I attached some clear hose and could see it very well! Since I had decided to go with an M/E Wagner PCV valve anyway, I removed the PCV valve from the Billet Specialties housing and stuffed it with stainless Scotch Brite. Then ran the hose at a slight upward angle in case it wants to drain back into the valve cover.

Then I got a very inexpensive aluminum catch can for about $40 on Amazon, with a sight glass and drain plug. Stuffed the can full of Scotch Brite and made a tube for the inlet hose to reach the bottom of the can. No tube for the outlet nipple so the incoming air has to run up through the stainless filtering before it exits. Reamed all the fittings uniformly to prevent airflow restrictions. Finally, got rid of the cheap clear plastic hose in favor of some good fuel injection grade. After all this, the PCV hose is now dry where it enters the carb. I don't know if it helps or hurts but I like the idea of oil staying where it belongs. Not a drop in the can after one full summer. After three years now, the oil has not reached the sight glass yet. But now that you brought it up, I guess I'll have to pull the plug and check just to be sure.

 

I’ve been experimenting with various catch can designs in many of my cars. They all collect oil.
212000 mile 4 cylinder about 4.5 to 5 oz every 5000 miles.
DI 6 cylinder 70000 miles about 3 to 4 oz per 5000 miles. This engine concerns me the most due to the Direct injection design.

if a catch can doesn’t collect something or very little, it’s likely a poor design or maybe a brand new engine with nice tight rings. Engines all create some blow by.