Catch Cans...

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Originally Posted By: spasm3
Originally Posted By: SteveSRT8

If you have tons of blow by and poor sealing then you will have lots of oily vapor flowing through your PCV. If you have a normal running car then you may have a slightly cleaner intake tract. But it's a classic case of "want" versus "need".



I totally get what you are saying Steve, but i think a lot of interest here is for DI engines. That's my interest.


Thank you for your understanding. I agree the whole DI thing is a different animal, but it truly does seem that most mfgrs have figured out the valve deposit thing now. I really think you will find that the problem is non-existent in vehicles that are run hard versus those who tool around town and never get rolling at speed for any appreciable time. This is also in line with both Mazda and VW who have stated that hard running for an extended period seems to help.

Despite all those who feel impugned when someone disagrees with the groupthink that occurs here, I am not telling anyone what to do. I am simply telling them that a lack of catch cans has had zero effect here on my cars and trucks, both personal and business use.
 
Originally Posted By: UberArchetype
Originally Posted By: SteveSRT8
If you have tons of blow by and poor sealing then you will have lots of oily vapor flowing through your PCV. If you have a normal running car then you may have a slightly cleaner intake tract.

And everything in between. Shall those seeing shades of grey call it needed wants? Maybe time is an issue so a judgement call to determine the vehicle's expected or desired length of service with or without would be appropriate? Oh wait - that's a want, not a need! Maybe we only really "need" the car until next week...
smirk.gif



Other than very specific applications there is no proof anywhere that a catch can will do anything other than clean the intake up a bit for those who use one. As stated previously, I have zero problems with folks wanting to use one. I simply want others who do not to realize they are not hurting anything by not using one. I have personally operated service vans from brand new to 500k miles without one and they ran great right up till their sale, so they are definitely not needed on GM V8 applications.
 
The use of one is entirely situational.

Turbo and DI (gas or diesel) is the worst, because it coats the insides of the intercooler, reducing its efficiency, fouls sensors, and breaks down charge air couplers. That is before it starts fouling intake valves.

Can an engine run like that for half of forever? More or less. Would you really want that going on? Not really.
 
Originally Posted By: SteveSRT8
I simply want others who do not to realize they are not hurting anything by not using one.

This is an explicit contradiction to your earlier statement about where they are beneficial. I'll quote it for you, if necessary. Citing your personal experience as some sort of axiom to follow is not only disingenuous, but also a perfect example of the Doesn't Follow Fallacy, as well. I won't be responding to you any further in this thread, since your intent appears to be reinforcing an irrelevant personal opinion.

Originally Posted By: DoubleWasp
The use of one is entirely situational

Exactly.
 
Only one response to that: hahahaha.

Might want to read what I said a bit more carefully. When many millions of us get by just fine without one it's pretty hard to make the case ain't it?

And I never suggested their use at all!
 
Last edited:
Originally Posted By: rooflessVW
I used to believe in catch cans.

After walnut blasting a few cars with them installed, I'm over it.


Yep, and I have heard this on the VW forums as well. Those pesky facts again...
 
The new DI LT1 put in Camaros & Corvettes have a catch can installed at the factory that drains the oil caught back into the oil pan.

On the other hand.....I have had 100's of N/A port injected engines dynoed over the years & have never seen a HP/TQ drop off from not running a catch can.
 
Originally Posted By: clinebarger
The new DI LT1 put in Camaros & Corvettes have a catch can installed at the factory that drains the oil caught back into the oil pan.

On the other hand.....I have had 100's of N/A port injected engines dynoed over the years & have never seen a HP/TQ drop off from not running a catch can.



NA port injection is the best for this. I can't tell you how many times I took apart engines to find the intake looking like a tar field, and the intake ports after the injectors looking like brand new. That fuel spray is just super nice for cleaning.

The ideal arrangement for Turbo/DI would be a water injection system. Not only would it improve power and keep everything spotless, but it would also knock down Nox emissions and vanquish LSPI. Only problem is that nobody seems to make a system immune from malfunction. "Malfunction" being a pump overrun resulting in hydrolocking and destruction of the engine.

Problem is that water injection kit manufacturers are eating cake, selling $90 worth of parts for $500-$1300 so there is zero stress to do any development right now.
 
Originally Posted By: SteveSRT8
Originally Posted By: rooflessVW
I used to believe in catch cans.

After walnut blasting a few cars with them installed, I'm over it.


Yep, and I have heard this on the VW forums as well. Those pesky facts again...


Facts?! There are "experts" firmly entrenched in both camps on this subject. Including vw folks. I wouldnt call anything concerning catch cans a fact other than:
1. There is no downside other than time installing and $ spent.
2. It does limit some blow-by byproduct from entering the intake.
 
use a small air pump to suck on the crankcase and just dump it over board. NOT into the intake stream. i know it wont pass EPA specs. but it is MY engine.
 
Originally Posted By: DoubleWasp
Originally Posted By: clinebarger
The new DI LT1 put in Camaros & Corvettes have a catch can installed at the factory that drains the oil caught back into the oil pan.

On the other hand.....I have had 100's of N/A port injected engines dynoed over the years & have never seen a HP/TQ drop off from not running a catch can.



NA port injection is the best for this. I can't tell you how many times I took apart engines to find the intake looking like a tar field, and the intake ports after the injectors looking like brand new. That fuel spray is just super nice for cleaning.

The ideal arrangement for Turbo/DI would be a water injection system. Not only would it improve power and keep everything spotless, but it would also knock down Nox emissions and vanquish LSPI. Only problem is that nobody seems to make a system immune from malfunction. "Malfunction" being a pump overrun resulting in hydrolocking and destruction of the engine.

Problem is that water injection kit manufacturers are eating cake, selling $90 worth of parts for $500-$1300 so there is zero stress to do any development right now.



I'm not arguing with your analysis, The intake tract can look pretty nasty....Especially with EGR in the mix. But I have never seen an actual case of it hurting power output or causing pre-ignition/spark knock issues on a healthy N/A MPI engine.

Another interesting subject is manufacturers running more Ignition Lead than needed.
 
Originally Posted By: Olas
Also,

Yeah, but road draft tubes left us in the 1960s, and for very good reasons.

Look at any carbureted VW, road draft tube vents straight into airbox with no 'fresh air in' hose and no valve. And every motorbike ever.

Road draft isnt as 'long dead' as you think..


read all THREE words...

"Road draft tubes"...not vented into the airbox, which is what you were railing at in the first place and thus my comment...those go to the intake, road draft tubes to the...well...road.
 
Originally Posted By: clinebarger
Originally Posted By: DoubleWasp
Originally Posted By: clinebarger
The new DI LT1 put in Camaros & Corvettes have a catch can installed at the factory that drains the oil caught back into the oil pan.

On the other hand.....I have had 100's of N/A port injected engines dynoed over the years & have never seen a HP/TQ drop off from not running a catch can.



NA port injection is the best for this. I can't tell you how many times I took apart engines to find the intake looking like a tar field, and the intake ports after the injectors looking like brand new. That fuel spray is just super nice for cleaning.

The ideal arrangement for Turbo/DI would be a water injection system. Not only would it improve power and keep everything spotless, but it would also knock down Nox emissions and vanquish LSPI. Only problem is that nobody seems to make a system immune from malfunction. "Malfunction" being a pump overrun resulting in hydrolocking and destruction of the engine.

Problem is that water injection kit manufacturers are eating cake, selling $90 worth of parts for $500-$1300 so there is zero stress to do any development right now.



I'm not arguing with your analysis, The intake tract can look pretty nasty....Especially with EGR in the mix. But I have never seen an actual case of it hurting power output or causing pre-ignition/spark knock issues on a healthy N/A MPI engine.

Another interesting subject is manufacturers running more Ignition Lead than needed.


In MPI? No, they don't seem to suffer at all.
 
The best catch can is venting into an oil bath aircleaner...or like I did for a while, into a K&N. Venting into a carburettor is not good, which is why my motorcycles vent to atmo. On the BMW I used to find crud in the emulsion tubes, not there if it doesn't vent into the intakes.
 
Originally Posted By: Olas
Back to the poop analogy - waste is waste, it shouldn't go back in. Anybody disagree?
Yes. Better it goes back into your intake (which can handle it without problems if properly designed) than into your neighbors' lungs.
 
I have one on each of my vehicles. A 2005 Mustang Gt with 50K miles and a Edelbrock supercharger and a 2017 Ram 1500 5.7 HEMI which is 5 months old. Both collect about a teaspoon every 500 miles, with LOTS of hard acceleration. Which is about a months worth on the Ram and three months on the Mustang. There is absolutely no seat of the pants difference with or without. But the cost and effort was minimal, so why not?
 
My bad, in the context of this thread I took it to mean any non-PCV system.

I still disagree with feeding oxygen deprived blowby into the intake as it is not combustible and so entirely worthless, granted dry blowby is better than wet blowby but both are worse than straight undiluted atmosphere.
 
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