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I always check my catch can and overflow before I start making passes at the track, but the catch can is almost always dry.
It's vented to the atmosphere so there isn't any vacuum on it which helps with that.
I always check my catch can and overflow before I start making passes at the track, but the catch can is almost always dry.
It's vented to the atmosphere so there isn't any vacuum on it which helps with that.
Without some kind of vacuum source drawing crankcase air through the catch can it isn't doing a darn thing for you.
Originally Posted by ddnspider
A 100 hard miles on the dyno is going to product some junk in the catchcan depending on how loose everything is. Doesn't seem crazy.
I don't care if it was on the dyno and run hard, a full catch can after 500 miles is pretty awful.
Any kind of high rpm use (like dyno time) will fill the can faster. Colder air temps cause a lot (I mean a whole lot) of water condensation because the can itself is cold. I have a huge can on my truck and it fills very fast in winter with mostly water from condensation. It freezes up and is such a PIA that I now remove it in winter. That can is at least twice as large as what most people use and I have to dump it twice every fuel tank in winter.
Originally Posted by Rich-L79
Without some kind of vacuum source drawing crankcase air through the catch can it isn't doing a darn thing for you.
Street cars use vacuum because of all the low throttle driving. That's not going to work with a race car that's spending a lot of time at full throttle. Best to reconfigure your PCV if you ever decide to do a day at the road track. Unless you have incredibly good baffling, then the can is going to fill up during a few sessions of high rpm racing.
I get a lug of smelly water every time i looked at it. No oil though yet, but going turbo soon and change of placement nearer engine guessing it will have less water....we will see
I was surprised to find mine full after ~500 miles. Probably 100 or so hard ones on dyno.
If your catch can system is for NA then it's likely the vacuum from the intake drew oil from the catch can after it filled into the intake.
I suggest you remove the throttle body and examine the inside of the intake for oil contamination.
If your catch can system is for a boosted application double check the plumbing to make sure the check valves open and close correctly determined by whether the engine is NA or when it is running with boost.
For example: with boost the intake is pressurized. If there isn't any check valve in the hose running into the intake for NA, then boost will blow back into the can forcing the full can of oil to flow back in the wrong direction. The plumbing for boost is critical so make sure you have the correct catch can for a boosted application with the correct number of ports and check valves in the hoses exiting from the can.
If the can is full when in boost oil from the can would flow back into the turbo or charger and contaminate all of the pipes and accumulate inside the fmic tanks. Too much oil on the compressor wheel can cause it to be out of balance. NOT GOOD.
Last edited by dlandsvZ28; Jan 23, 2021 at 10:14 AM.
Reason: edit content
Any kind of high rpm use (like dyno time) will fill the can faster. Colder air temps cause a lot (I mean a whole lot) of water condensation because the can itself is cold. I have a huge can on my truck and it fills very fast in winter with mostly water from condensation. It freezes up and is such a PIA that I now remove it in winter. That can is at least twice as large as what most people use and I have to dump it twice every fuel tank in winter.
Street cars use vacuum because of all the low throttle driving. That's not going to work with a race car that's spending a lot of time at full throttle. Best to reconfigure your PCV if you ever decide to do a day at the road track. Unless you have incredibly good baffling, then the can is going to fill up during a few sessions of high rpm racing.
No, it shouldn't fill up faster. I've had my car on the dyno numerous times and done drag racing and road racing numerous times. Never has the catch can filled up any faster than in everyday use. And it shouldn't. There should also be scant oil contamination in the intake tract assuming the catch can is doing what it is supposed to do. My catch can rarely has more than a few teaspoons of oil in it between oil changes. The only reason it would be filling up as fast as the OP describes is if the engine has horrible baffling which is something you don't want regardless if you have a catch can or not. The PCV system should only be pulling gasses out of the crankcase, not an excessive amount of oil and if it is pulling a lot of oil there is something wrong with the PCV system itself. If you have a catch can and the intake tract is very oily then the catch can isn't really doing what it is supposed to be doing.
There are too many variables. We don't know how his system is run. Saying the tanks shouldn't fill up is moronic. It depends how you have it plumbed, fuel run, size of catch can, temperature/humidity etc... With E-85 and a vac operated pump I'd get a healthy amount of water. It could fill up a tiny catch can in 500 miles easy. I ran a large can and it had mostly water in it... not coolant, water with a slight oil film. Start up an E85 car on a cold humid day and it chugs like a steam engine for the first few minutes. Its perfectly normal. If there's coolant in it, that's a different story.
I actually prefer to vent mine and not run vacuum to it. It doesn't "do nothing". What it does, is provide a vented chamber so I don't spit oil out an open filter vent on the VC. It also allows me to see if I "push" any water during a pass from a leaky HG.
I'm not looking to run 200k on my turbo race toys. I prefer not to suck hot oil mist and garbage back through my turbo and charge pipe.
If you make real power, you’re gonna get oil/water in catch cans. It’s best to vent valve cover towards the front.
I ran a catch can between the valley pan nipple and the intake manifold for several months and it picked up maybe a half teaspoon of dribble. It also provided ZERO relief of crankcase pressure, which is important if you're running 20#s of boost.
I now have -12 on the front passenger side VC and rear drivers side VC with baffling that runs to a vented can.. Of course this setup doesnt clean the crankcase air of contaminants, but I dont care. I could run a second catch can with a vacuum source if I wanted to, but my engine doesnt seem to produce much, if any.
Originally Posted by Forcefed86
There are too many variables. We don't know how his system is run. Saying the tanks shouldn't fill up is moronic. It depends how you have it plumbed, fuel run, size of catch can, temperature/humidity etc... With E-85 and a vac operated pump I'd get a healthy amount of water. It could fill up a tiny catch can in 500 miles easy. I ran a large can and it had mostly water in it... not coolant, water with a slight oil film. Start up an E85 car on a cold humid day and it chugs like a steam engine for the first few minutes. Its perfectly normal. If there's coolant in it, that's a different story.
I actually prefer to vent mine and not run vacuum to it. It doesn't "do nothing". What it does, is provide a vented chamber so I don't spit oil out an open filter vent on the VC. It also allows me to see if I "push" any water during a pass from a leaky HG.
I'm not looking to run 200k on my turbo race toys. I prefer not to suck hot oil mist and garbage back through my turbo and charge pipe.
Agree^
Running it vented to atmosphere also allows crankcase pressure to escape under boosted conditions. This saves your front and rear main seals from popping out. Not fun to fix.
In my opinion its more important to provide boost pressure to escape than to collect 1/2 teaspoon of dribble.
Originally Posted by Rich-L79
No, it shouldn't fill up faster. I've had my car on the dyno numerous times and done drag racing and road racing numerous times. Never has the catch can filled up any faster than in everyday use. And it shouldn't. There should also be scant oil contamination in the intake tract assuming the catch can is doing what it is supposed to do. My catch can rarely has more than a few teaspoons of oil in it between oil changes. The only reason it would be filling up as fast as the OP describes is if the engine has horrible baffling which is something you don't want regardless if you have a catch can or not. The PCV system should only be pulling gasses out of the crankcase, not an excessive amount of oil and if it is pulling a lot of oil there is something wrong with the PCV system itself. If you have a catch can and the intake tract is very oily then the catch can isn't really doing what it is supposed to be doing.
agree with Rich. To the OP: How do you have your catch can setup? Where is it connected? Which model is it?
Depends on the time of the year for me. It is real humid year round in Louisiana. I get a mixture of unburnt fuel, oil, and water. I get about 5 oz every 500 miles of hard driving (95% of the time). I also have a large length of hose going to and from my dual catch cans.
There's a couple of things to consider that will affect the performance of your crankcase ventilation system.
If the line going to the can for ventilation comes off a valve cover with no baffle or is located at the back of the valve cover it will suck more oil.
If the engine has wider ring gaps and as a result experiences more positive crank case pressure it can fill the can faster.
If the engine has an insufficiently sized breather system, it will fill the can faster as well as blow seals and dipstick tubes.
Using a large breather line (or two) to the can (or cans) is always a good idea, a -12 off the front of the valve cover gave me plenty of flow and kept oil out of the line during hard acceleration.
The only thing I ever drained from my can was water that smelled like fuel, this was using pump gas only, no E85.
This was using a PCV style vent can as well so it kept the inside of the engine nice and clean, two oil changes a year probably helped with that too lol.
Without some kind of vacuum source drawing crankcase air through the catch can it isn't doing a darn thing for you.
Oh really? So when I remove it and the engine decides it wants to stop working right and pressurizes the crankcase with moonboost, Is the oil going to just stay where I tell it to?
Oh really? So when I remove it and the engine decides it wants to stop working right and pressurizes the crankcase with moonboost, Is the oil going to just stay where I tell it to?
You are correct, that was a misstatement by me. If the can is vented to the atmosphere the crankcase pressure will just push out through the catch can.
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