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Catch can?

137K views 142 replies 82 participants last post by  ChargerPursuit 
#1 ·
What does the catch can really do anyway? Horsepower? General performance? Someone let me know please
 
#110 ·
Hemissary-

I enjoyed reading that post you made back 9-15-10(didn't want to quote the whole dang thing). A lot of that info is very good, although the lack of emperical data included means we have to take the authors word for it. It DOES make sence to me though.

Heck, I had the same knock before and after my CC install.

Here are the FACTS (imo facts LOL) about catch cans.

1. They look pretty dang good
2. They are functional, ie. they do "catch oil".
3. It doesn't hurt the engine to have one installed.
4. Did I mention how cool they look? Blingggg. lol


My questions are:

1. has it been proven with emperical data that oil in the intake causes knock?
2. If that is a yes, then by function of the CC, keeping that oil out would reduce knock, right?
3. If it's a no, then the CC would be ineffective in that regard.
4. Does it really keep the TB clean? Does "some" gunk on the back side of the tb butterfly impede airflow as to reduce performance, horsepower/tq, engine logevity, or how it runs period?


Now I'll go read the rest of the thread to most likely answer my questions LOL
 
#111 ·
Hemissary-

I enjoyed reading that post you made back 9-15-10(didn't want to quote the whole dang thing). A lot of that info is very good, although the lack of emperical data included means we have to take the authors word for it. It DOES make sence to me though.

Heck, I had the same knock before and after my CC install.

Here are the FACTS (imo facts LOL) about catch cans.

1. They look pretty dang good
2. They are functional, ie. they do "catch oil".
3. It doesn't hurt the engine to have one installed.
4. Did I mention how cool they look? Blingggg. lol

My questions are:

1. has it been proven with emperical data that oil in the intake causes knock?
2. If that is a yes, then by function of the CC, keeping that oil out would reduce knock, right?
3. If it's a no, then the CC would be ineffective in that regard.
4. Does it really keep the TB clean? Does "some" gunk on the back side of the tb butterfly impede airflow as to reduce performance, horsepower/tq, engine logevity, or how it runs period?

Now I'll go read the rest of the thread to most likely answer my questions LOL
Thanks for the compliment;

1. No; in fact the engineers state lifting oil off the plenum floor, at any rpm, is not occuring
4. Yes it does; because the PVC dumps crankcase air containing aerosoled oil and blowby (partially burned air/fuel that has escaped past the rings), less oil present means less oil to gather on the backside of the throttle plate. Let's be clear here though; a throttle plate, nor the engine gives two craps of a sparrow's bug dinner whether it is shiny clean or laden with deposits. It (the system) is controlling airflow...that's it.
 
#112 ·
Great read. Interesting to note my car is the quickest STOCK 6.1 LX and has no catch can.

Hmmmm.

My car also has no measurable oil consumption. None. I have cleaned the intake once, and there was some oil in it. But every single vehicle I have had the intake off of in the last decade has had the exact same problem! And yet they run well with no catch can.

And thankfully, manufacturer durability testing involves running parts to failure, not to some arbitrary mileage number. Some may confuse this with the emissions warranty which is specifically based on mileage.
 
#114 ·
Great read. Interesting to note my car is the quickest STOCK 6.1 LX and has no catch can.

Hmmmm.

My car also has no measurable oil consumption. None. I have cleaned the intake once, and there was some oil in it. But every single vehicle I have had the intake off of in the last decade has had the exact same problem! And yet they run well with no catch can.

And thankfully, manufacturer durability testing involves running parts to failure, not to some arbitrary mileage number. Some may confuse this with the emissions warranty which is specifically based on mileage.
Just think about how much quicker your car would be WITH a catch can! ;)
 
#115 · (Edited)
Good thread with lots of interesting information. I happen to have been doing a whole lot of research on blow-by and catch cans recently and have a few points to add:

1) Your PCV valve - even when working properly - will often close completely under high engine load conditions. When this happens, the blow-by has no way to escape the crankcase other than back through the "makeup air" line that runs from your oil filll neck to the stock airbox. So, even with your catchcan installed in the PCV line, when you need it most (high engine load = maximum blow-by generation) it will be blocked off. This is a much bigger problem on forced induction cars and high-output N/A motors (big cubic inches and/or higher compression ratios).

2) Yes, Chrysler and most other engine manufacturers incorporate some type of air-oil separator device into their valve cover or intake manifold designs. The trouble is these are necessarily simple, zero-maintenance devices and sacrifice significant performance to those ends. To get the majority of the oili out of blow-by gasses, you need a filter with the capabiliity to catch very small <5 micron) diameter oil droplets - that's where most of the volume of oil in blow-by gas is at. You will catch some with a simpler device, but very likely less than half.

3) If I had a forced induction engine, I would have catch cans on both the makeup air and PCV lines - period. And, if I drove it hard (in boost), often, I would expect to fill both at the same rate.

4) A catch can is one piece of a crankcase ventillation system. I do believe that measureable performance gains can be had with a properly functioning CCV system versus a vented-to-atmosphere or (more commonly) mis-plumbed system. I'm working on gathering data to prove this point - will share when complete.

This is one of those simple things that's not nearly as simple as it seems like it should be!
 
#127 ·
I really didn't think a catch can was anything. I had not intended to buy 1. Then I was able to buy a used one cheap enough to try it. I installed it & after 3 weeks had some oil pooled in it. All that would have went into the intake. Now, does it hurt anything if it did? I don't know. However I can't imagine it hurting anything either to keep it from getting into the intake.
I always wondered why my intake on other cars was a black mess inside them.
 
#129 ·
This thread should just be locked... what could possibly be learned now when it has devolved to members flinging poo at each other. Seems all the relevant points have been discussed in depth.
 
#131 ·
I will not read all the previous posts...so I have to dog in this fight!
But, CATCH CANS WORK!
I have a 2011 SRT8 392 and self installed a catch can.
I have not even gotten to my next oil change, but was curious to see if it was working.
I got this quarter cup at 4K. And, unlike my V6, it was not at all sludgy....but nice and thin!

 
#134 ·
Has anyone installed a LT1 vacuum pump on any of these motors? I have this setup on my Buick GN with fantastic results. I plumbed in 2 Moroso breathers on top of my valve covers, run them under my intake to a T fitting, then goes directly to the LT! pump. The pump is triggered by a Racetronix wiring harness and has a hobb switch activating the system at 3pounds of boost. It can also be triggered by TPS voltage etc. Never tested to see if it adds any hp. but it certainly vented the crankcase pressure effectively and minimized the leaks and intake build up.
 
#135 ·
Personally I don't see a lot of point in a catch can. (opinion based on my experiences so don't get your panties bunched). The amount of oil that is put into any given cylinder on a single stroke is so minute you wouldn't notice. If it was significant, no way a car would pass emissions. Most of what is coming out in the can is vapor from the oil that gets condensed, also including water. Neither of these in small quantities will hurt anything. In fact, some top cylinder lubricant might actually be beneficial. People used to put a marvel mystery oil drip into their intake to decrease engine wear.

Anyway, as an example, if you assume an average of 2000 rpm for 5000 miles at 30 miles an hour (my vehicle's average out to 30 mph when i compare mileage and hours and do the math). If you assume 1 quart of consumed oil over 5000 miles (which is higher than I have experienced on any of my hemi's), you would get 0.00000004 ounces per cylinder per revolution.

So reality is the only benefit comes to a cleaner intake. Which if you keep the dirt out better won't become caked with junk. You might want to re-think your air filter choice is you have a lot of dirt sticking to the minute oil there.
 
#136 ·
Personally I don't see a lot of point in a catch can. (opinion based on my experiences so don't get your panties bunched). The amount of oil that is put into any given cylinder on a single stroke is so minute you wouldn't notice. If it was significant, no way a car would pass emissions. Most of what is coming out in the can is vapor from the oil that gets condensed, also including water. Neither of these in small quantities will hurt anything. In fact, some top cylinder lubricant might actually be beneficial. People used to put a marvel mystery oil drip into their intake to decrease engine wear.

Anyway, as an example, if you assume an average of 2000 rpm for 5000 miles at 30 miles an hour (my vehicle's average out to 30 mph when i compare mileage and hours and do the math). If you assume 1 quart of consumed oil over 5000 miles (which is higher than I have experienced on any of my hemi's), you would get 0.00000004 ounces per cylinder per revolution.

So reality is the only benefit comes to a cleaner intake. Which if you keep the dirt out better won't become caked with junk. You might want to re-think your air filter choice is you have a lot of dirt sticking to the minute oil there.
But it looks cool.
 
#143 · (Edited)
Not a fan of CAI. Don't waste money. Evidence shows most CAI's let more dirt into engine. The oil I have in my catch cans proves that they are effective, at least to me. I'm also impressed with people who have the skills to work on internals of combustion engine. It's a great skill to have. But, that has nothing to do with whether or not a catch can helps to keep the engine clean.
 
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