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Catch can

23K views 118 replies 46 participants last post by  15R/T 
#1 ·
What is the purpose of this? I'm new to all this so excuse me for not knowing. I just wonder why I need this for a brand new 40 something grand car.
 
#2 ·
A catch can mounts in line with the PCV system in your car. it helps to catch oil and oil vapors that normally are not removed while traveling through the pcv system. The late model Hemi is notorious for excess oil blow by, and this oil makes its way through the pcv and ends up back in your intake. The effect long term is oil build up in the intake, and throttle body. Therefore many owners chose to add a catch can to catch this excess oil before it routes back to the intake.

We carry several options that will work for your scat pack, let us know if we can help
 
#10 ·
Race cars typically dont have a PVC system on them, normally just vent to the atmosphere, which can be messy. The average person in the average car who never shifts over 2000 rpm and seldom runs high rpm frequently or for extended periods will see much less need for a catch can, the system will not pass that much oil. High rpm blasts cause larger amounts of oil vapor in the crankcase which will put more through the vent system. Oil in the intake is no big deal, its just passing through. Small amounts in the combustion chambers is no super big deal for a daily driver. It gets to be a bigger deal for those concerned about max performance and controlling detonation.
 
#11 · (Edited)
I'm of the school of thought that a can can't hurt and might help, but some quick math with some assumptions:

Assume in a 6000 mile oil change interval the can captures 2oz (~4 TBS) of oil.
With an approximate range of 300 miles per tank, that equates to ~20 tanks of gas, or slightly less than 400 gallons (400 gallons = 51200 ounces)

Assuming the can is only catching half of the oil circulating back, that's a contaimitation rate of 1 ounce (~2 TBS, or approx. a stingy shot glass) of oil for every 25600 ounces (200 gallons) of gas, and without a catch can 1oz to 12800 (100 gallons)

Just to put it into more familiar terms, that's a few drops of oil in a 55 gallon fish tank.

I'm not saying that's good or bad, harmful or not, but the ratio is seemingly small.
 
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#15 · (Edited)
I had been on the fence about getting one after seeing the pics posted here. I recently pulled the PVC hose to the intake and the hose from the air cleaner to the throttle body. I was expecting both to look nasty but they look pretty damn clean. I'm at 5 years and 78k, so I'm not gonna sweat it. If I start running at the track I may rethink things...
 
#17 · (Edited)
thanks, fixed post: From PCV to intake and air cleaner to throttle body
 
#18 ·
So why does somebody need an Oil Catch Can Tank? Cheap insurance for your engine.

Valve rings do not create a perfect seal. If they did the pistons would not be able to move up and down. Because there is a tiny gap between the cylinders walls and the pistons, a little bit of pressure is able to escape into the valve cover area and crankcase. At the same time burnt oils are also escaping into the valve cover area. This is called “blow-by”. The contents are nasty and will eventually make its way into the PCV line and breather.

The PCV line will recycle these burnt solids back into your intake manifold which will increase the level of carbon solids, and reduce your octane levels. For a boosted engine, it's even worse. The breather line will recirculate some of these oils into the intake which will go into the intercooler. Of course, the intercooler works best when the interior surfaces are nice and clean. When the breather line returns any fumes with oils into the intake, this will start to coat the inside of the intercooler with oil, and reduce the heat exchange efficiencies.

So, the simplest solution is to insert an oil catch tank can into each line, this gives these heavy oil solids a place to enter and pool. There are many shapes and sizes, and even different configurations which are closed-loop, and open loop.

There are various negative effects of not having a properly designed Catch Can installed and allowing excess oil vapor contaminates the intake system from the stock PCV system, such as:

• Throttle body and/or Mass Air Flow Sensor (if so equipped) malfunction or failure.
• Air filter, intercooler (if so equipped) and intake ducting contamination if oil pools and run back out the intake system after engine shutdown
• Reduced octane of the air/fuel mixture, which can cause detonation and the ECM (Engine Control Module) to retard timing, thereby reducing engine power.
• Excessive carbon build-up on valves, piston crowns, combustion chambers and spark plugs. This also increases the chance of detonation and power loss.

For more information (including photos) see:

https://www.redline-motorworks.com/kb_results.asp?ID=8
 
#19 · (Edited)
Ok wow!! 2 1/2 tablespoons of oil. Ive had the can installed for a little over 1000 miles. Seems like a lot of oil IMO, but full disclosure, I have been driving this car HARD and putting her away WET!



I also pulled my cables and they do not look gunked up at all, however they do look wet, which they should. I don't think you can assume you don't need a catch can based on the amount of gunk in the hoses. I don't think the hoses will ever really gunk up much. This is an active hose regardless of catch can installation or not. I think the fact that there is ANY oil in this can is an indication of the need for this can. Am I way off base here?



And wow to CUDA...
So why does somebody need an Oil Catch Can Tank...
This is the best one post summary of a catch can Ive read.
 
#20 ·
I have seen a lot of people say "SRT has said blah blah" but all I have ever found was hearsay. I thought Dodge's official position was that it was not needed because any oil that makes it through will be eventually burned off anyway. I would say that NO would be my answer on "look there's some oil in there so I need this, right?" as being an answer for needing it. I am still on the fence though...I simply don't wanna spend $150 on something questionable at best.
 
#21 ·
I have seen a lot of people say "SRT has said blah blah" but all I have ever found was hearsay. I thought Dodge's official position was that it was not needed because any oil that makes it through will be eventually burned off anyway. I would say that NO would be my answer on "look there's some oil in there so I need this, right?" as being an answer for needing it. I am still on the fence though...I simply don't wanna spend $150 on something questionable at best.
Do you like seeing smoke clouds when you start it up after a day? That's what happens once the oil builds up and puddles in the intake. Added one to my SRT and it does not smoke anymore on start up.
 
#22 ·
For the first few thousand miles on my 2014 R/T I didn't have a catch can. When I did my T.B. swap I noticed a puddle of oil in the bottom on the intake. Oil is definitely pooling in the intakes of the cars that don't have a can installed. I reached my hand into my intake and wiped out what oil I could. It saturated a rag pretty well.

I would imagine some of this residual pooling is being sucked into the engine during WOT operations. This oil is, for a fact, reducing the octane rating of your fuel. No question about that.

I guess the key question is... how much oil actually makes it into the combustion chamber. I would have to think the oil would eventually gum up the intake ports and valves to some degree. I'm sure Tier 1 gas would help with this problem, but I would prefer not to contribute to carbon build up on my piston tops.
 
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#35 ·
Yes, and this is why Diablo themselves started selling and recommending catch cans. In fact some tuners won't even tune cars without them installed due to the impact on false knock due to octane.

From the Diablo site
Piston engines produce pressure in the crankcase (basically the lower half if you picture from the crankshaft down) as the pistons pump up and down. If that pressure were to build it can reduce ring seal, hence the purpose of the ventilation system.
Because of emissions reasons, however, that pressure cannot be vented to the atmosphere, so the manufacturers have to route it into the intake manifold so that it can be burned in the combustion chamber. The gasses from the crankcase carry emulsified oil that coats the intake runners (producing that sludge you see when you remove the manifold on a high-mileage engine) and degrades the octane of the atomized fuel entering the combustion chamber. In other words, it's killing the octane rating on that big tank of premium you just paid for.
 
#25 ·
Obviously from all the folks that say the catch can is needed and those that say the catch can isn't needed................it's a personal thing.


The way I see it is if the engine engineers thought a catch can and it's usefulness out weighs the 1000-2000 mile maintenance step for Hemi owners to have to do or have done, they would have put a catch can on these engines. I prefer to have a catch can and see the oil build up after 1500 miles and drain it.


Again, it's a personal thing. One side will sing the praises of a catch can and the other side will state a catch can is unnecessary, and this disagreement will go on forever.
 
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#26 · (Edited)
and the catch can traps x% of the oil and the other 100-x% is still passing through. X might be 10%, 50%, 90%.

I'll stay on the fence, a catch can seemingly can't hurt and might help
 
#27 ·
Well I asked someone reputable (who deals with data logging/tuning) directly the question I posed above and they stated that they have seen detonation/knock caused by oil that could have been lessened by a cc. This satisfies my curiosity and I will now have to change my tune on this topic.
 
#29 ·
Hmmm. Is that info specific to a hemi? I'd wonder if compression ratio, intake flow, AFR, spark temperature, displacement or other factors are in play.

Thinking out loud and talking out my ass, but nonetheless, curious to know more.
 
#28 ·
Yea, I see carbon bits in my catch can when opened, why would i want junk going into my intake and combustion lol people who are undecided will be forever until they install one and see for them self's lol lol...
 
#30 · (Edited)
Yea,,, wants the engine gets tuned could be a lot of variables lol even with a catch can still oil getting in the intake its not 100% lol so why not get a catch can lol 'If' it can't hurt must be a good idea to get one lol lol lol


If you are thinking keeping the car then $150 price tag is peanuts lol lol

Those who buy new cars every 2- 3 years you do not even have to have your oil changed just add and save yourself money lol lol let alone buying a catch can lol for that matter!!!
 
#39 ·
I purchased my SRT new, and at 4,000 ish miles I noticed when I started it up after it sat all night it would blow a cloud of blue smoke. If you notice most of the Hell Cat start up videos that Dodge did they smoked on start up! I installed the can on my car and after a week or so it hasn't smoked anymore. I get about 6 tablespoons of oil every oil change. It works, I didn't like the smokey start ups like an engine with drippy valve stem seals.
 
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