Proper oil catch can setup for a road racer

[Calan]

...I have been holding off on buying a catch can for this very reason all my buddies who have one still have a mess even if they have it hooked up correctly (in their eyes ) ...

Brent, check out that last link I posted. Since that was written, I've drained another 1-1/2 pints of oil from the VC catch can, and still have none whatsoever in my intake tract.

BTW, if any of you are interested...I've actually logged the CC pressure at the VC breather outlet on my stroker, and the most I see at 25psi of boost is just a little over 1 psi. Under vac conditions, it's barely readable.

Also interesting is the fact that after 5000 miles or so, I've emptied the VC breather can twice, but the one on the PCV side still hasn't collected enough oil to register in the sight glass (and I have verified that it is flowing air as expected). So with an improved stock setup (in my car at least), the VC breather side flows WAY more oil vapor and areosols than is ever drawn through the PCV valve under normal driving. I always expected it to be more, but not by such a large difference.

 

[MIdsm]

Does anyone vent the bottom end as well as the valve cover? If one looks at the evo head and block there are many more oil returns and it appears that the bottom end may get much better ventilation. At high RPM the blowby pressurizes the crank case and the pressurized air rushes through just a few oil returns into the valve cover and then out. Could all that air rushing through small passages cause some oil not to drain back into the crank case and remain in the head and cause oil starvation (I'm talking about a prolonged high rpm use)?

Also, as previously stated, one ought to use large diameter hoses for venting as the air velocityinside the hose drops and helps decrease loss of oil.

I would still use two catch cans, not vented to atmosphere, with internaI baffling and filter screen (such as unifoam universal air filter), slightly modified from what drivemusicnow described. One catch can would be connected to the turbo intake pipe, the valve cover and the crank case (bottom of the catch can). At prolonged high rpm use the turbo would create vacuum and evacuate the crank case while turbo would injest filtered crankcase air (less oil). Under engine deceleration the catch can would be emptied back intosaid the crank case. The second catch can would be connected to the crank case and the IM and have a check valve (PCV valve) in this line. Under high boost the catch can would empty into the crank case that's under low pressure due to first catch can system. Under deceleration the air would travel from turbo intake pipe into the first catch can into the crankcase and valve cover then into the second catch can and then past the check valve into the intake manifold. Theoretically, with this setup the crankcase should be under low pressure majority of the time. The oily crankcase air would be filtered inside the catch cans so the engine shouldn't injest large quantities of oil under both acceleration and deceleration. The effect of oily crankcase air on engines has been discussed widely. The crankcase would also be getting fresh air circulation leading to less contaminants in the oil. In my opinion this would be the most effective setup this side of vacuum pump or a dry sump setup.

A race car could use the venturi tubes in the exhaust but I would vent the crankcase not the valve cover.

Please pardon my ramblings.

 

[snowborder714]

Anybody have any opinions on the model Craig posted? Eric and I would like to get started on these, but would like some feedback. Some of you probably know more than us about a good can setup, so let us hear it! I don't think we have anything else we'd like to change on it, but are open to any suggestions.

 

[talontsi18]

I finally took some pictures of my exhaust venturi setup. The venturi needs to be welded in at a angle to create the proper vacum, it fits perfect between the sub-frame and the axle. The hose that I used from the venturi to the valve cover is 5/8". I used a short section of 5/16" hose over the nipple of the valve cover then clamped the 5/8" hose over that. You could probably use a in line catch can if you wanted. I bought the parts from jegs.com, and the part numbers are in the pictures. The Moroso venturi even has a small cut in the tube to know how far to weld the tube in.

 

[Scott McIntyre]

talontsi18... Any chance you could try sticking a vacuum gauge on the end of that hose and measure it at idle & WOT?

 

[mike96]

I finally took some pictures of my exhaust venturi setup. The venturi needs to be welded in at a angle to create the proper vacum, it fits perfect between the sub-frame and the axle. The hose that I used from the venturi to the valve cover is 5/8". I used a short section of 5/16" hose over the nipple of the valve cover then clamped the 5/8" hose over that. You could probably use a in line catch can if you wanted. I bought the parts from jegs.com, and the part numbers are in the pictures. The Moroso venturi even has a small cut in the tube to know how far to weld the tube in.

one question for you. does using the crank evacuation setup make the factory PCV setup worthless.

 

[talontsi18]

talontsi18... Any chance you could try sticking a vacuum gauge on the end of that hose and measure it at idle & WOT?

I'm interested in how much vacuum this setup creates as well, ill see if I can measure it this weekend. I'm not sure if I have any gauges that would work at my house but ill let you know.

one question for you. does using the crank evacuation setup make the factory PCV setup worthless.

My PCV setup is still intact, I plan to remove the PCV and replace it with a fitting then run a in-line check valve before a sealed catch can, probably Calan's style (best catch can I've seen) then to my SMIM. For now it remains stock.

 

[mike96]

My PCV setup is still intact, I plan to remove the PCV and replace it with a fitting then run a in-line check valve before a sealed catch can, probably Calan's style (best catch can I've seen) then to my SMIM. For now it remains stock.

OK but the question is still do you really need the factory PCV setup with the exhaust evacuation in place... think about it for a second. the way the factory PCV works, under any condition that would cause a vacuum in the intake manifold, whatever gases are created by the hot oil are sucked from the valve cover into the intake so that the engine can burn them off. under boost conditions the PCV closes and (hopefully) keeps all positive pressures inside of the intake where the engine can make full use of the available air. the other port running from the valve cover to the intake before the turbo basically does the same thing only it does this while the turbo is doing its job by forcing air into the intake manifold, everything before the turbo is now the grater vacuum source.

with the exhaust acting as the vacuum source and pulling the hot oil/gas mix from the engine, is there really a need for the intake manifold to perform this task, other than appeasing emissions inspections. only problems i see would be that it might bring up some of the "not so good" readings when you were to get your emissions tested. but as long as you were plumbing the tubing in place before the catalytic converter that should take care of most of those problems. the other problem i see might be that it could not have as high of a vacuum for proper crank ventilation during idle and low speed engine operation...

that being said then wouldn't it be just as effective and a lot less work (and money for that matter because you wouldn't need to buy the extra check valve, unless you were worried that the PCV valve wouldn't hack it and wanted the extra assurance) and still do exactly what you are doing if i were to weld in a pipe to the exhaust at the 45 degree angle then run the hose up through one of the gaps in the manifold to the PCV check valve.this way the PCV valve will keep (hopefully) exhaust gases from entering the engine, it will look stock, and because you wont have the need to have a vacuum source while under boost conditions (the exhaust should be doing this) you wont need the hose running from the valve cover to the intake before the turbo, that line can be caped off or plugged and would completely eliminate the need for a catch can and all that mess you get in the intake from oil in the intake manifold/turbo/inter cooler/ ETC. ETC.

 

[Calan]

You're not thinking about the second function of the stock PCV system, which is crankcase ventilation. During off-boost driving, the purpose of the PCV is to pull fresh air through the engine for ventilation (turbo inlet > VC breather > PCV > IM), in order to prevent hydrocarbon buildup and contamination of the oil.

During boost, the PCV is out of the loop and the VC breather's sole purpose is to vent excess crankcase pressure.

These guys are talking mostly about a dedicated race setup (I think), in which case the oil is going to be changed very often and CC pressure is going to be the main concern, and ventilation/oil contamination probably isn't an issue. In that case, I think having a PCV that draws "fresh" air from the exhaust (assuming no check valve at the venturi) would be worse than none at all.

For a stock type setup that handles both the excess pressure and the ventilation, I don't think the exhaust venturi would be the best solution.

**************

BTW - talontsi18... Thanks for the compliment.

 

[Scott McIntyre]

You're not thinking about the second function of the stock PCV system, which is crankcase ventilation. During off-boost driving, the purpose of the PCV is to pull fresh air through the engine for ventilation (turbo inlet > VC breather > PCV > IM), in order to prevent hydrocarbon buildup and contamination of the oil.

Interesting point!

Perhaps a solution to that would be to add a third fitting on the valve cover, install a cheap USPlastic check valve inline and cap it with a crankcase vent filter. This would allow fresh air to enter the crankcase, but not escape through the filter.

I know... it's starting to get over complicated. WTF

 

[Calan]

I know... it's starting to get over complicated. WTF

PCV discussions usually do for some reason.

 

[my4ATEurV8]

How do you guys think running a line from the vc to a filtered catch can, then from the catch can to the upper wall of the oil pan, then some place after the filtered catch can tee in a line from pre turbo inlet for vacuum. its a ruff idea and probably needs some tweaking. but i believe this idea would eliminate positive case pressure and filter out micro particles of oil from going through the turbo.
i think some type of valve or other system would be necessary at the line going into the oil pan to keep oil from traveling up the line under increased vacuum from an in-gear deceleration during a corner.

im thinking of using this with a speed density setup

 

[Calan]

How do you guys think running a line from the vc to a filtered catch can, then from the catch can to the upper wall of the oil pan, then some place after the filtered catch can tee in a line from pre turbo inlet for vacuum. ... i think some type of valve or other system would be necessary at the line going into the oil pan to keep oil from traveling up the line under increased vacuum from an in-gear deceleration during a corner....

If I'm correctly picturing what you're describing, why would you want to do this? If you are talking about running the catch can drain back into the oil pan, I can give you one very good reason why this is a bad idea.

When the hot crankcase gases hit the can (which is relatively cool), they cause moisture inside the can to condense and mix with the other liquids that have been filtered and collected. So now sitting in the bottom of the catch can is a mix of liquid hydrocarbons (mostly unburnt fuel), water, and oil. Do you really want this to be dumped back into your engine's oil supply?

Not to sound mean, but people have been "inventing" a better DSM PCV setup for years, and there are STILL only two ways to really do it correctly IMHO. I know this because I was one of those people that thought I knew more than everyone else and tried to invent a better PCV system a few times, and failed miserably.

1. Run an improved version of the stock setup (with added catch cans, and a check valve between the PCV and IM), which maintains both pressure relief and ventilation, or

2. Run a pure pressure relief setup with one or more lines from the VC into a catch can that is either sealed and tied into the intake or open to atmosphere. This is fine for race applications where higher CC pressures are seen and more relief is needed, but it doesn't do anything for ventilating the CC under normal driving. But this isn't really a factor if the oil is changed every 1000 miles or so.

The exhaust venturi setup is just a variation on #2.

...i believe this idea would eliminate positive case pressure and filter out micro particles of oil from going through the turbo...

A good catch can in a stock PCV configuration accomplishes this. I have removed over a quart of filtered crap from my VC can in 5000 miles, and I still don't have any oil whatsoever in the intake snorkel.

im thinking of using this with a speed density setup

Crankcase ventilation has nothing to do with how you meter incoming air, for the most part. (Ehhhh... well ok. It can have an effect that you have to deal with on a GM MAF in blow-through, but it's more of a small annoyance than anything).

 

[snowborder714]

Do you really want this to be dumped back into your engine's oil supply?

I just told him the exact same thing via PM.

 

[my4ATEurV8]

Ya that does make sense, i never even thought of water vapor. thanks for the warning.
the reason behind my idea of ventilation and pressure relief while also recirculating the oil back to the pan was, trying to figure out a type of "set it and forget it system". But like all other ideas, rarely are perfected on the first try! most get scrapped. i wonder i can figure out a way to get the oil back to the pan with an inline filter of some sort that's good enough to grab all the crap, and still have proper breathing of the system.
will look more into this.

 

[Calan]

i wonder i can figure out a way to get the oil back to the pan with an inline filter of some sort that's good enough to grab all the crap, and still have proper breathing of the system.
will look more into this.

How are you going to separate "good" oil from dissolved hydrocarbons, water, and all the other crap?

It's only an extra 30 seconds to turn a valve and drain the can about every other time you change the oil. Tuning in a decent radio station is more work than that.

If that is too much work, I think you're better off with a straight stock setup with no cans or filters at all.

 

[my4ATEurV8]

How are you going to separate "good" oil from dissolved hydrocarbons, water, and all the other crap?

It's only an extra 30 seconds to turn a valve and drain the can about every other time you change the oil. Tuning in a decent radio station is more work than that.

If that is too much work, I think you're better off with a straight stock setup with no cans or filters at all.

take it easy big guy! just trying something different, to be as efficient as possible.
im still doing my research on the subject, so why don't you hold your slick comments.
while i am researching it maybe i will see it your way, realizing it will do more harm than good. but on the other hand, i could actually figure it out and present my findings with undeniable proof, use what ive learned through trial and error and actually make the detailed writeup when i do it to my car, only for you to read about it a few months from now and do it to your own car! but then again, i could be wrong
at least i will know exactly why it will, or will not work. i think thats a lot better than someone like you calling me lazy and i shouldn't even try by sticking with my stock setup.

 

[Calan]

I think you are the one that needs to take it easy man...I wasn't calling you lazy. I think it's great for people to experiment...I've done plenty of it myself. It's just that there have been countless posts saying "Hey guys...I figured out a better PCV setup", and I have yet to see a setup better than the two mentioned. Not saying it can't be done...I'm just desensitized to it. If you have something that works well, I'll be the first to congratulate you on it, and maybe even adapt it to my car like you said.

I didn't mean any of those comments as smart-ass remarks. I'm just saying that if draining a catch can is more than you (or anybody) wants to mess with, then a stock setup is probably the best option...or possibly the venturi setup, depending on the situation.

But if you can find a cheap way to pull good oil out of a mix of oil, gas, and other stuff...more power to you! There would be $$$$$$ in your future. (But even then there would still be the question of is it worth saving 30 seconds to drain a can).

 

[my4ATEurV8]

finding a cheap way to pull it off is the idea. it also gives me something to do.
and the 30 seconds. its more like a couple min at most. you gotta pop the hood, get somthing to drain into, and a red rag just to be handy, then let the oil drip for a few extra seconds to get most of it out. its a pain. im just kidding. its no pain. im actually using an ebay catch can.
i just like experimenting. it all comes down to opinion. ill still post my findings.

 

[Calan]

Well good luck, but I can't comprehend doing it.

Take a pint of oil, a pint of gasoline, a half can of brake cleaner, and a cup of water and mix them all together really well.

Now... pull the pint of oil back out for me.

 

[Calan]

Guys, I posted a tech article on this for future reference.

http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

Feel free to PM me with questions, comments, mistakes, etc.

 

[99gst_racer]

Hey Craig, how is your current evacuation set-up plumbed? Two lines from the VC to the catch can and one from the can to the intake tube (pre-turbo)?

 

[snowborder714]

He only has one line from the valve cover.

 

[Calan]

Right now I'm still running just the single -6AN line from an enlarged stock VC port to a single inlet can, and then a 5/8" hose from the can to the turbo inlet. With that setup, the most positive pressure I've logged on the stroker is .6 psi, at around 23-24 psi boost I think (I need to check the log for the actual boost value).

Once I get the rear suspension back under the car and on the road, I may add another line or up the existing one to -8AN and see if the CC stays in constant vacuum. I'd like to get some hard data on what effect different line sizes makes.

****

Oh yeah... the PCV side is basically stock, with the addition of a check valve and one of my cans (which has yet to collect hardly any oil).

It's pretty much exactly the same as the "Improved Stock" setup drawing in the article ^^^.

EDIT:

vvv Thanks Adam...glad you liked it.

 

[black_gst]

Guys, I posted a tech article on this for future reference.

http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

Feel free to PM me with questions, comments, mistakes, etc.

I just read that write up and it is awesome. Even though i pretty much knew everything and the right way to make a good setup it was still informative yet simple enough for the newst newb!