Catch cans

[dmann]

My last track day the dipstick showed my oil levels going down so I have to assume it was because of the G forces. So, before my next track days I will be adding a square wheel setup with 285s for even more grip with a set of R888r tires. I think its time to do a catch can.
A couple questions though, whats the preferred brand and do I need both sides since most turns are right handers?

thanks

David

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[JohnD]

I got a JLT. It's simple to install, uses the factory Ford connectors and you just unscrew the bottom to empty it. Most people find they get nothing in the driver side units. I get maybe a teaspoon full after a lapping day in the passenger side one.

 

[dmann]

hmm, then where do the oil go? Does it burn it because of the higher RPMs?

 

[JohnD]

If you don't have a catch can it goes into the intake and gets burned in the engine. Which sounds simple. But it isn't, because if it eats enough at a time it can cause engine damage by causing an improper mixture to get called for by the computer running the show. It's not what you want happening at high revs on a road course.

 

[dmann]

roger that

 

[ddozier]

If you are running a PCV system then you will want to run catch cans on both sides, it really does not have much to do with cornering forces. It is mostly about the high RPM's and the amount of blow by from the low-tension rings on the OEM pistons. At higher RPMs the engine will produce a bit of blow by that will pressurize the block and can force air from the PCV system back to the intake to be ingested by the motor. Oil in the intake is the result of this air moving through the PCV system under normal conditions and it is amplified at higher RPMs.

I have run the JLT and another brand and they all seem to do a fairly good job. As a side note on installing them, the cooler you can keep the catch can the more effective they are at filtering out oil vapors. All of these catch cans rely on the oil vapors to condense on a medium within the catch can, if the medium and the oil vapors are at the same temperature the oil will not condense and the catch can is not doing anything. Most install locations are not ideal for keeping them cool. If you have the flexibility to mount them in a cooler place than most of the store bought solution do they will be much more effective. A catch can is also a early warning device for the health of the engine, if you are filling catch cans at track days your motor is not healthy.

Dave

 

[el-guapin]

Good insight. Thanks for sharing!

 

[dmann]

If you are running a PCV system then you will want to run catch cans on both sides, it really does not have much to do with cornering forces. It is mostly about the high RPM's and the amount of blow by from the low-tension rings on the OEM pistons. At higher RPMs the engine will produce a bit of blow by that will pressurize the block and can force air from the PCV system back to the intake to be ingested by the motor. Oil in the intake is the result of this air moving through the PCV system under normal conditions and it is amplified at higher RPMs.

I have run the JLT and another brand and they all seem to do a fairly good job. As a side note on installing them, the cooler you can keep the catch can the more effective they are at filtering out oil vapors. All of these catch cans rely on the oil vapors to condense on a medium within the catch can, if the medium and the oil vapors are at the same temperature the oil will not condense and the catch can is not doing anything. Most install locations are not ideal for keeping them cool. If you have the flexibility to mount them in a cooler place than most of the store bought solution do they will be much more effective. A catch can is also a early warning device for the health of the engine, if you are filling catch cans at track days your motor is not healthy.

Dave

Much appreciated! I had no idea it was from the rpm's. Its a PVC system. So, Both Sides it is then.

 

[Brooks_Church]

I run the dual Radium catch cans. I like them a lot and the dipsticks that are built in are super nice to see when I need to empty them. My drivers side almost never sees any oil, even after a full track weekend and 2k mile drive.

 

[NightmareMoon]

I run the dual Radium catch cans. I like them a lot and the dipsticks that are built in are super nice to see when I need to empty them. My drivers side almost never sees any oil, even after a full track weekend and 2k mile drive.

See thats the thing, and why I dont see the need to run a carch can on the Driver’s side.

The PCV system is not symmetrical in how it works on the left and right sides. IIRC the right passenger side deals with positive venting and the left side is more of an equalizing intake or something like that. I read a detailed description but it was quite a while ago, but the takeaway is there is a design reason why we dont get much if any oil vented out the divers side.

 

[ddozier]

See thats the thing, and why I dont see the need to run a carch can on the Driver’s side.

The PCV system is not symmetrical in how it works on the left and right sides. IIRC the right passenger side deals with positive venting and the left side is more of an equalizing intake or something like that. I read a detailed description but it was quite a while ago, but the takeaway is there is a design reason why we dont get much if any oil vented out the divers side.

If everything is healthy in the motor you would still get oil vapors and need a catch can to help remove them from the PCV system. Even with a healthy motor there is blow-by and oil vapor making its way to the intake via the PCV. To prevent oil from entering the intake and pooling in the intake you add a catch can. There are two air paths to the intake for the PCV so you should have two catch cans. Because the PCV system is designed to draw air in a certain direction oil tends to end up on the passenger side more than the drivers side but that does not mean there is no oil vapor making its way from the drivers side valve cover. It just means that most of it is on the passenger side.

This would be true if all things were perfect, but all things are not. The issues come in after an engine is worn in a bit and things start to loosen up. The rings on these cars have very little tension and as a result can have gasses slip past the rings in high RPM and high heat environments. once more pressure is in the PCV system than can be overcome by the very minor vac draw created on the passenger valve cover then there is a possibility for the drivers side airflow to reverse as the increased pressure in the crank looks for a path to free air. If you have both sides with catch cans it is a very good tool to determine the health of the engine. If you track the car for years and there is a known rate of oil collected in the catch cans then something changes and the cans are filling at a higher rate that should lead you to conclude there is something that needs to be checked. You would perform a compression check and determine a baseline. If the condition continues or gets worse and compression has changed you know you have a sealing issue with the rings. You can get to the same conclusion by monitoring oil use but having any motor oil being burned in combustion on a performance motor is not a good idea, and with a 8-10qt oil system it is harder to notice. Catch cans themselves are not 100% efficient at removing oil vapor and you still will end up consuming some oil and having oil in the intake, but the least amount the better.

Dave

 

[Trackaholic]

Ad ddozier mentoined, the PCV system acts as a loop to cycle air through the engine and ventilate the crankcase oil mist. The driver side acts as the intake, while the passenger side acts as an exhaust. Therefore, any mist would typically go out the passenger side, which is why it catches more fluid.

However, under high G's it is possible for a burp of oil to work its way into the PCV system. If this happens you can get a relatively large amount coming out into the engine intake, which can foul the airflow sensors and cause the engine to lose power, go into limp mode, etc. This type of thing is very rare but could happen to either the passenger or driver side. A catch can will act as a reservoir to trap this mass of oil.

My friend had his Viper go into limp mode on corner exit due to this phenomenon. He almost lost control due to the rapid weight transfer when the engine cut out. When he got back into the pits, there was oil dripping out of his intake and he though he somehow blew his engine, but it turned out to be from the PCV system. He installed some catch cans after that experience.

I run the UPR setup on my GT350, which has a large passenger side container that one can empty, and a smaller driver's side component that just stays on top of the valve cover and drains back into the engine. It's a nice kit but expensive compared to some others.

-T

 

[64Chevy]

I'm a track guy, but won't likely be tracking my GT350. I get the benefit of catch cans for engine health monitoring, but in the non-track environment does enough oil ingestion occur to be an issue (I get that in the perfect world no oil would be ingested, but in that world catch cans would be 100% effective)? I also get there is really no downside to catch cans, just looking for some upside in the non-tracked car.

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