rorrapalooza

I was wondering if anyone on here was running an oil catch can on their C4? Id like to try to keep the intake a little cleaner from oil and I think this should hopefully do the trick.

Any suggestions for good mounting locations? I have a crossfire and I was thinking maybe a small one would fit in-line between the driver valve cover PCV and vacuum port; tucked right beneath the front driver side of the air cleaner cover, especially since ive removed the lug used to lift the motor. Alternatively, I thought maybe I could fit a catch can where all the vacuum valves for the AIR injection are currently. What do you guys think?

Is a catch can needed between the passenger valve cover and air filter too? im not entirely sure what the function of this side is to be honest.

billschroeder5842

There is not a "preferred" location as few people (as far as I know) have done this.

I'd look to mount it where the washer fluid container is located on the passenger side up front. You will have more room and with the location being out of the hot engine compartment would provide better "separation" in the cooler environment. You will have to run longer hoses, but no biggie.

Tom400CFI

I think it's a waste of time...something to do to fill a "hobbiest's" time. The CFI is a wet intake; your intake is constantly being "washed" by gasoline that has detergent in it.



The purpose is fresh/clean air to replace the contaminated air in the oil'ed areas. During times of manifold vacuum, fresh air is drawn in to the valve cover. No benefit at that time. At WOT, there will likely be a slight positive pressure in the valve cover (from blow by) and some air with oil vapor can pass through that hose, into the air filter housing and be ingested by the TB's.

rorrapalooza

That makes sense. I thought maybe it had a check valve that prevented flow into the crankcase at that point.

DMITTZ

I just did a catch can install on my L-98, 1988 Corvette.

Here's a link to the page on my thread that covers the catch can install, scroll down and the post is near the bottom of the page:

https://www.corvetteforum.com/forums...vol-2-a-4.html

Install is pretty strait forward, I put the catch can on the passenger's side wheel well but where ever you have room for it should work.

Hope that helps!

-DMITTZ

rorrapalooza

Thats true, but when I opened up the stock intake for the first time in its life a few months ago, I found some puddles of oil in the intake, specifically in the low spots in front of the runners. i'm sure there was some gas mixed in too, but the puddles were black, so I think mostly oil. I would estimate one to two cubic inches total were pooled in various spots.

If I took a corner hard, a cylinder might suck in 1/2 a teaspoon of oil all at once and cause detonation (just my speculation though)

The renegade I have now seems to not be as bad for low spots, but really id just like to keep the motor cleaner from buildups, and it would be nice if when I take a look in the plenum it wasn't black.

There was some sludge too from combining exhaust fumes and oil probably left over from before the EGR was defeated years ago (never ran well with it for whatever reason).

Thanks! Ill definitely be taking a look

billschroeder5842

I have a catch can on my 2015 Challenger and it make a big difference. You can not imagine the crap that it collects.

Now, having said that, I do not have one on my LT5 with 67k. I bought the car a few months ago and have not given it much thought.

The occasional can of Sea Foam will do about the same. Plus, you have all cool smoke coming from the exhaust to **** off the neighbors.

So, if you are going to put A LOT of miles on it and have a penchant for cheap grade oil, a catch can would not hurt.

Or, advance the timing a bit, run slightly hotter plugs and run a can of Sea Foam a couple of times a year..

ex-x-fire

If you are collecting oil in a catch can, it sounds like you have blow by.

Tom400CFI

Especially with a car that has a wet manifold.

DMITTZ

All engines have some blow-by that will cause a positive pressure in the crankcase, that is why you have to have either a vent or a pcv system.

The point of the catch can is to stop oil mist from being sucked into the intake.

No you don't 'need' a catch can but it is beneficial and for the few dollars and small amount of effort why not add one.

Tom400CFI

Because it is not doing anything beneficial that can be measured. It's treating a psychological problem...not an actual one.

Aardwolf

Stock engine put enough oil in the exhaust to get black flagged at tracks for smoke. New engine doesn't put much in the can but as it ages it will tell me about the engine condition.

DMITTZ

I don't mean any disrespect to you Tom400CFi so please don't take this the wrong way.

However, I have to disagree. While it is certainly true that engines with wet intakes will get less carbon build up due to the fuel mist having a cleaning effect compared to say a new D.I engine. It has been my experience when taking apart an older engine that there is some amount of gunk/carbon build up on the intake tract and the intake valves. So that says to me that overtime oil mist from the PCV along with the EGR are causing deposits.

I think the effects tend to be more noticeable while under race conditions for whatever reason.

As I noted before, you don't 'need' to run a catch can but it is beneficial. No your engines intake won't get large deposits right away without it but over the long term not using one will lead to increased deposits. Also even If the oil mist somehow does not leave buildup on the intake don't forget the effects of burning extra oil in the combustion chamber. Extra oil getting into the combustion chamber can cause the octane of the air/fuel mixture to be reduced causing detonation and thus requiring the computer to retard timing to compensate (reduced power). The extra oil being burnt in the combustion chamber will also cause the engine to expel a dirtier exhaust (added pollution) which is more likely to fowl the O2 sensor, the EGR valve and the CAT.

So as you can see the benefits go beyond just keeping the intake clean. So while you don't 'need' to run one it is beneficial given the small cost IMHO.

Tom400CFI

No disrespect taken. Excellent points, but all must be taken in context; We're not just discussing the diff between EFI and DI...In the case of DI, I think a catch can is very important; nothing will clean the intake, ports or valves other than a deliberate cleaning service. In a Port FI engine (TPI/LT1) the ports valves are washed, but not the runners, so one could make a case there, for the runners and plenum (however insignificant the build up is, to performance). In the OP's case, the whole intake system is washed, since it's TBI; fuel is injected before the throttle plates so the entire TB, plenum, runners ports and valves are washed by fuel. The only time oil/carbon build up should be a concern is extended WOT use and/or excessive blow by -a worn out engine. The effects of build up are more noticable under "race conditions", b/c there is no manifold vacuum to pull fresh air the right "direction" through the PCV system, and there is likely positive crank case pressure from blow by...so "oil humid" air will be pushed into the filtered air intake system.

Another question; are we putting catch can(s) on BOTH sides of the PCV system? A can on the fresh air side is only providing a very tiny benefit on a street/part throttle driven engine.



I totally agree with all of your points...except the "beneficial" point, and I guess that would have to be defined. Precisely what is the benefit? "Less build up". So, what does that produce for you? My experience is 200,000+ mile vehicles that haven't suffered in any measurable way from this "build up"...so I don't see the benefit of the catch can, from a performance stand point. It sure won't hurt...and you're right that the cost is low. So I'm back to what I said above; it's a great "hobbiest's" project, I feel.

.

DMITTZ

I'm not quite sure I understand what you mean by both sides of the PCV system?

I would think all of the air coming from crankcase through the PCV system into the intake should go through the Catch Can. Maybe I'm not understanding what you are referring too?



I have not worked on a CFI engine before, but I have done some work on TBI engines in the past and I did notice they had some build up of gunk/carbon on the intake tract. Also my own engine (L-98) the first time I took the heads off had some build-up on the head intake ports and valves, which are being sprayed pretty much directly by the fuel injectors. I think the O.P also mentioned that he had some oil pooling in his intake after some months of use. This would suggest to me that the fuel mist on wet intakes may not completely prevent build-ups related to oil mist... However, I do agree with you that it is very unlikley the deposits will ever kill the engine, but they may have some effect on how well it preforms, how much effect is hard to say. I suspect on an engine with minimal blowby (rings in good shape) the effect is small, but on an older high milage engine with worn rings the effect may be more pronounced.

Having said this possible deposits on the intake tract are really the least important issue with oil mist getting into the intake. For me the bigger issue is the effect that I mentioned above that the extra oil getting into the intake charge and effecting the octane of the air/fuel mixture in the combustion chamber which could cause detonation resulting in the computer having to pull timing to compensate (reduced power). Not to mention creating added pollution and increasing the chances of fowling the 02 sensor, the Cat and EGR.

You are correct in that you that you don't 'need' to use a catch can and your motor can run ok without one. However, for me given the small cost, eliminating all these possible problems by using a catch can just made sense. If you feel that a catch can is not beneficial and prefer to not use one that's your call. Even through we have differing opinions on this issue. I think this discussion on catch cans has been has been good since now the O.P has lots of info/opinions to make his decision so I guess its up to him to decide if he wants to run one or not.

Aardwolf

Mine is hooked up with the normal PCV on the drivers side and a catch can on the passenger side instead of going into the intake/TB. I tried vents on each VC but there was to much oil film. Pretty typical for these engines to be dirty, a lot of carbon on the pistons and intakes very oily. If your engine is still stock/higher mileage I would add one and see what you catch. Maybe it's in great shape and not used hard and you won't need to leave it on. Easy to make a temporary one with a soda bottle.

Tom400CFI

Under manifold vacuum, air path should be:
Air Filter > snorkel (air filter housing on the CFI) > into 3/8" hose > valve cover > through crank case/valley > opposite side valve cover > into PCV valve > 3/8" hose > into plenum...then burned.

SO, if you believe a catch can is necessary, then there is value in installing one between the PCV valve and the manifold/plenum.

Under zero manifold vacuum (WOT) air path should be somewhat backward from above:
Combustion gasses that leak past rings > up through valley into rocker area on the fresh air side valve cover (opposite PCV side) > 3/8" hose > into snorkel > through TB, into plenum...then burned.

SO, if you believe a catch can is necessary, for WOT/low vacuum events, there is value in installing one between that valve cover and the intake snorkel.



Fuel may or may not completely clean carbon. I'd say it depends on the concentration of fuel in a given area....and how much contamination you're throwing at the intake (with oil vapor from blow by). HERE are some pics of my healthy, 150k+ engine's intake ports and valves. I agree with you completely, that a tightly sealing engine with little blow by should remain relatively unaffected by oil/carbon build up. I agree that an "older" (poorer sealing) engine would be much more greatly affected...but MY thoughts are that that engine needs a rebuild...not a catch can. JMO though.



I totally


.

rorrapalooza

Youre absolutely right, this has been a good discussion to follow.

My impression of the motor is that its in good shape; it has excellent oil pressure, maybe even too high, and ive only ever observed one little puff of blowby smoke from the exhaust in 19 years and that was on a WOT dyno run at 4000 RPM. Its got 85,000 miles.

That being said, im gonna go with a catch can on the driver side PCV, just to keep things a little cleaner

I just need to decide on a mounting location... probably either driver wheel well or where the AIR injection valves are now

rorrapalooza

Would there be any downside to replacing the passenger side PCV with a simple breather? It seems to me that might be even better because that way the air that enters the crankcase would be filtered in some capacity

billschroeder5842

Yes, you would be blowing old oil all over the inside of your engine compartment.

Frankly I think you are over thinking this thing. I have a catch can and I know it works. I can see how it works every time I pour the sh*t out that would have gotten sucked into my engine. I'm always amazed at how much is actually captured.

Now, your engine will be just fine without a catch can. If you have one on one side and are worried about the other, just run a piece of hose over the intake and connect with at TEE fitting inot the other side. Done.

I have mine because I'm a tad OCD and I like it.