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Unread 09-07-2010, 04:47 PM   #1
RevXtreme 1
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Default PCV oil separating catch cans

Have done threads in the past, but thought I would start a new one:
Understanding the need for
a proper PCV oil separating catchcan

Any engine driven hard will ingest a certain amount of oil into the intake air system resulting in loss of power, detonation, and long term carbon buildup on the pistons & valves reducing the velocity and flow through the engine.

Preventing this on a street driven car subject to emissions requires some simple modifications to the closed OEM PCV system.

On all out race applications where emission rules do not apply, this is accomplished in different ways, but proper crankcase ventilation is a must! The crankcase gets filled with harmful combustion byproducts that if not evacuated will cause internal damage to your engine and shorten the usable life. These byproducts include: Sulfuric acids, abrasive carbon particles, unburnt fuel, water, and more. If you do not have a proper crankcase evacuation system these compounds will condense inside the engine and mix with the oil as well as begin corroding internal parts. It is NOT enough to just vent the crankcase pressure through a breather, but it must be flushed with a filtered fresh air source to carry these out & away. In an OEM system, these are burnt in the combustion chamber & further in the catalytic converters.

In an off-road or race application, the engine is normally not used to burn them off.
At the very least drag only motors have a scavenge evac system in the header collectors to pull vac, and anyone that's serious has a belt driven vac pump.....especially the Alky motors due to the amount of moisture the alcohol introduces to the crankcase. Next time your at a sanctioned (NHRA/IHRA) race walk around the pits and look at the dragster motors and how they evac. You will see that any w/a vac pump run a relief valve on the opposite valve cover because if you pull any more than 14-15" of vac you start to pull oil off the wrist pins & rod journals.

I have run a pro team for 7 years and we run most every sanctioned track in the Eastern US and have yet to see a high HP dragster or door car w/out evac.
*
Want to see whats in your oil? A simple oil analysis will show you how much harmful stuff ends up in it.


The oil analysis will show the acid build up....and no, it takes a year or two before you would see any substantial damage to your internal engine parts.....but an easy way is after 6 months or so of running like you describe pull a valve cover and look and the corrosion from the vapors on your rocker arms. This is the first place it is visible.

More of my background? My team holds several local, divisional, National, & World championships in Super Pro, Super Comp, Quick rod, Top Dragster, and non-electronics.....I am also a graduate of the Reher Morrison Racing engine building school and have been an engine builder for over 35 years as well as having an engineering & machinist background. Take a little time & read David Reher's tech tips......a world of information: http://www.rehermorrison.com/blog/?cat=3

Bottom line is, w/out a proper evac system you WILL sustain long term engine damage. It may take a few years to notice, but I build motors 6 days a week when not racing and see the results first hand.

There are several other ways for oil mist to enter the intake manifold, the PCV system is the most common with the fresh air make up source (the fitting on the top rear of your throttle body) being the second most common. To eliminate that you need to cap the TB fitting and run a valve cover breather (installed as far from the crankcase vent as possible...ideally you want to pull filtered fresh air in one valve cover & evac it out the other or the LS6/LS2 style valley cover is second best) Then if it is excess crankcase pressure pushing oil vapor/mist out faster than the PCV can evac it you will see it pushed back through the line from the pass valve cover front to the TB and it is ingested from there. The 3rd point of ingestion is from reversion. This of course needs at least one piston/ring/bore/valveguide or seal issue that is allowing oil to be pulled into that one or more intake port and at high RPM's the reversion pulse will "push" that oil throughout the entire intake manifold. It will appear to have entered from the vac fitting that the PCV system uses but is really from one of the cylinders (reversion is a whole different process that is not widely understood but do a Google search and you can actually find some super high speed video of engines on dyno's where at high RPM's...9-10-12K plus the reversion cloud of A/F mixture is actually rising out of the intake runners or carb on a non fuel injected motor). To test for that just place a clean clear fuel filter inline between the catch can outlet and the vac fitting. If it gets oil on the can side, oil is coming through the can. If it first appears on the intake vacuum side, then it is reversion so you have a deeper issue.
*
Having engine smoke or excess crankcase pressure? There may be a deeper issue. On the LS motors we pull apart it is usually # 7 ringland broken between the compression & middle ring, or the land itself broke off at the top. We also find the top ringland pinched or crushed down on the top ring (comp. ring) and metal transfer along the piston side has caused the oil & scraper ring to stick allowing oil & blow-by. Also, try this: at idle (vac is at it's greatest when at idle or when the throttle blade closes from high RPM's) remove the oil fill cap and hold your hand over it. Does it pull a slight suction? If so, all is good with most of the system and I doubt you have a damaged piston/ring/bore. But if there is ANY pressure pushing back you have a deeper issue and that is the cause of the oil problem.

Now on big cam/stroker builds a can inline on the dirty side, and a can inline from the fresh air source may be needed (the bigger the bore & longer the stroke, the more crankcase pressure is built up) If it is forced induction, then you have a whole new process to deal with......and that is the PCV system works properly when at idle & non-boost, but when you start making boost you have switched from the intake manifold being negative atmosphere to a pressurized component and the PCV system is rendered useless and pressure escapes wherever it can. The solution then is to have one way check valves inline so the vacuum need for proper evacuation comes from in front of the compressor (head unit) through a line run to the air filter.

This is getting a bit long and I hope all can follow this, but if not ask me specific questions for clarification so this helps all. I'll go over every type of solution and the pros & cons of each....and remember, this problem is NOT just in the GM LS based engines, but is an issue with ALL modern closed systems. We just tear into our cars where as the Mercedes or Lincoln owner never even realizes there is an issue.

I also wanted to address the water in the oil. You will NOT fill your crankcase up in short order with just breathers. What happens is each time your engine reaches operating temp the unburnt fuel, water vapor, combustion by-products will gas or "flash-off" as vapor. But only the excess crankcase pressure being relieved through the breather will carry any of that out....and without a proper evac system, a good amount remains in the crankcase and re-condenses back to droplets that coat the internal engine parts as your motor cools down and it contaminates the oil. Every time you heat cycle you are adding more contamination and it is not very visible to just "look" at your oil....you need a professional analysis to see just what is accumulating in your oil and how it is breaking down its ability to protect...but the corrosion from the sulfuric acid is also very damaging over time (I'll try to post up some pics of parts showing just this in the near future). Just pull the dipstick on a diesel 20 miles after an oil change...it already "looks" black & dirty, but is still new and providing the proper protection. Sight is deceiving. Oil might look pretty clean or dirty but an analysis report will show destructive levels of contaminants.

And finally, some have gone so far as to cap off the entire system and run an open hose from each valve cover to near the ground. While this will eliminate all oil getting into the intake via the PCV system, the damage done by the hose with the least amount of air moving past it while at speed will suck dirt/sand/dust/water/and who knows what else directly into the motor via that valve cover. It may take some time (depending on how clean the roads you drive on are) but will result in premature engine wear & failure.

The solution for the street crowd is a properly designed, good functioning oil separating catchcan. Many are available on the market, but ONLY one designed with internal baffling and a good distance separating the inlet from the outlet. Many of the cans seen for low prices on Ebay, etc. are great looking, but are nothing but empty cans with two fittings attached. Do your homework & get a full understanding before you make your selection.



$124 shipped in the lower 48!!!!!

Special pricing on the RevX catchcan, the most effective can period for seperating oil mist/vapors from the PCV system.

For top mount SC use the standard configuration.

For turbo, Pro-charger, Vortech style specify the FI configuration:

The forced induction can is designed just for these applications. Unique design with integrated checkvalves prevents boost from pressurizing crankcase & provides for positive crankcase evacuation wether in boost or not.


Anyone that needs any diagrams or have questions for a specific application, just ask. Systems available for ANY application.

N/A or top mount supercharger model is $109 plus $15 S&H, and the forced induction for turbo, Procharger/Vortech/Paxton style add $20. Make sure you include all info on your build available to ensure you get the proper kit.


No anodized, but polished, brushed, or base/clear color to match as close as possible what you want.





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Unread 09-09-2010, 12:32 AM   #2
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Tracy, I notice that these catch cans apparently come with drain tubes attached. Were those tubes included with the cans for my car?
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Unread 09-09-2010, 08:48 AM   #3
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What all would I need for my LT1? What's my cheapest option if I want the canister black? Just painted, or powder coated?

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Unread 09-09-2010, 09:56 AM   #4
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Quote:
Originally Posted by Rich Z View Post
Tracy, I notice that these catch cans apparently come with drain tubes attached. Were those tubes included with the cans for my car?
No, it's part of the latest revision. I'll send you one.

Quote:
Originally Posted by shakedown067 View Post
What all would I need for my LT1? What's my cheapest option if I want the canister black? Just painted, or powder coated?

Black is no extra cost. You will need to find a good spot to mount it...anywhere you can fit it. The bracket can be bent to suit.

Here is another picture:

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Unread 09-09-2010, 10:04 AM   #5
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Cool! So where do the hoses go on the LT1? What exactly am I tapping into here?
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Unread 09-09-2010, 11:39 AM   #6
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Quote:
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No, it's part of the latest revision. I'll send you one.
Thanks Tracy, but won't I need TWO (2) of them, since I have a dual can setup?

What other changes were made in this latest revision, btw?

I guess a LOT has changed in the world since my build started.....
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Unread 09-09-2010, 11:41 AM   #7
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Quote:
Originally Posted by shakedown067 View Post
Cool! So where do the hoses go on the LT1? What exactly am I tapping into here?
Locate your PCV valve, and plumb the can inline with that hose. The vacuum side goes to the can outlet, and the crankcase side goes to the can inlet.
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Unread 09-09-2010, 05:05 PM   #8
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nice can!
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Unread 09-17-2010, 12:58 AM   #9
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Next chapter, "How do the pro drag guys do it"

This is not forced induction, but still 1000 hp plus motors and how important it is for these $20-$40,000 engines.

Below is the latest Top Dragster I'm rigging with new motor /Converter/Power Glide:





This is a 565 CI 14.5-1 CR, and runs on 118 octaine. Notice on the left side of the engine is a billet AeroSpace Components vacuum pump (Probably my favorite with the Moroso 4 vane second). This is a belt driven air pump hat pulls vacuum from the engines crankcase, much like your OEM PCV sysem does, but it does not use the intake manifold vacuum to evacuate the crankcase vapors, it pulls them with much more vauum than any OEM system, and this does several things. First, and most important, it removes the unburnt fuel, suspended carbon particles, sulfuric acid, moisture, and more harmful compounds that if not removed contaminate the engine oil and attack the metal surfaces of your engines internals. Second, the vacuum pulled is helpping reduce the parasitic loss and extra resistance that crankcase pressure causes (= more hp!), but with low tension rings it helps them seal better to deal with the high compression ratio.

Now there is a negative if to much vacuum is pulled in oil being pulled off the wrist pins and crank journals causing galling. We prevent that with an adjustable vacuum relief valve in one valve cover for fresh make up air to enter & control just how much vacuum is pulled:




We don't want to see more than 14-15inches of vacuum as this is about the threshold of maximum gains and little risk of galling.

Here are some close ups showing he pump, the containment catch can, and how it looks before the plumbing is complete:





And he fitting in the right side valve cover:






Notice that the vacuum relief valve is located at the rear of the left valve cover, and the outlet AN fitting is on the front of the right valve cover. This allows the most complet cross flushing possible to remove the harmfull combusion byproducts. The fresh air is pulled into the engine via the rear left side valve cover vacuum relief valve. it then travels around the rocker arms, and is pulled down the push rod valleys & oil return holes. Through the entire inner crankcase cavity, across to the right side of the crankcase, (all the while mixing with and pushing out the harmfull combustion byproducts) up the right side push rod valley & oil return holes, around the rocker arms, and out the front of the right side valve coer in a -12 AN fitting that then runs through a hose (not on yet, will finish the install tomorrow)to the inlet of the vacuum pump, and out to the 1 qt breathered catchcan to drain later. The majority will be water, with some nasty oil/contaminated soup. Why is the catchcan on this setup not closed and has a breather? Because it is not a closed system. This allows for NO possible ingestion into the he intake air charge so nothing but air & fuel enter the combustion chamber. Unless of course you have an internal engine issue such as worn valve giudes/seals, etc.

Hope that was not over anyomes head, but since this is a stickey I want to make regular contributions to help the average motorhead understand some of the complexities that so many don't understand properly or know how to deal wih this.
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