PCV/Catch Can/Crank Pressure

[tatertot91]

Hey sarge what brand of oil is this? Im kinda a rookie here lol...

Penzoil Platinum

[2000dreambird]

sarge where did you get your catch can? i seen some priced as much as $289 but its pretty much just a can with steel mesh and a couple lines

[2000dreambird]

also i always run mobile 1 is pp 10-30 really that much better the car has always had M1 in it so i just went with it...

[DVS LTx?]

Back in the day...

...but I need some help. I joined this forum just to get advice. I've been asking for help on LS1Tech.com and have a thread going on whether I should re-install my factory PCV system onto my new engine, or go the valve breather route. If you care for light reading:
http://www.ls1tech.com/forums/lt1-lt...eathers-2.html

Now first off, I'm running the olde LT1 mill. So we're a bit different. What I've been able to understand is that my system consists of:

1) an air breather tube that runs from my TB and into my passenger side valve cover.

... If i'm correct, this tube feeds fresh air into my engine to help move/cycle along the crankcase pressure and vapours.

2) a PCV pipe which exits a PCV hole on the driver's side of my intake manifold and runs down and into an opening in the front of my intake manifold (right under theTB).

... If i'm correct, connecting this pipe to the front opening of the intake manifold somehow causes a vacuum effect to pull out the pressure and vapour from the PCV (outlet) hole in the side of the intake manifold.


Here's my application: A new 383 LT1, XFI280 cam nothing crazy, AFR Eliminator 210 comp heads (pretty crazy! :P). NO AIR, NO EGR - car is not a daily driver and I don't care to pass emissions. This engine NA will make 500+hp at the flywheel.

The CONS: They guys at the shop putting my car together suggested I ditch the PCV system completely and just run valve cover breathers on either side.

The PROS: some people have argued I should run the PCV system (my engine builder in particular).

WHERE I'M LEANING: I "think" I'm close to deciding to re-install the entire PCV system onto my new engine, however there is NO FREAKIN way I ever want oil or mist or shit to ever back up through the air breather tube and into my TB or Intake opening - SO I'm thinking about installing a catch can in the middle of the air breather tube (between the TB and the passenger side valve cover). I've also been told NOT to include valve cover breathers if re-installing the PCV system with catch can.

My BIG question: I got the purpose or theory of the PCV system - relieving crankcase pressure & mist/fumes/garbage, etc. What I don't understand is in my LT1 the PCV system seems to be a closed system, OR at least a one way system. As far as I can gauge, the only opening to the outside atmosphere is the air breather tube which gets air via the TB. So there is where the cycle starts... goes into the passenger side valve cover, through the crankcase, up through a closed chamber within the intake manifold, out the PCV hole at the side of the intake manifold, BUT FROM THERE the PCV pipe just wraps around and sends the pressure/mist right back into the opening in the front of the intake manifold (under TB). Where does this pressure/shit go from there??? To me, it doesn't seem like the pressure is being releaved at all because its being spit right back into the intake - is this crap being routed back into the engine, or is it being routed into the intake plenum and down the intake runners???

IF the end of the PCV system is the second part (sending the pressure plus mist plus clean air directly into the intake plenum), then that is another route for mist/oil/shit to get blown into my intake...

Am I correct in this last part? (where the PCV system actually ends?). If so, then I would need a second catch can in the middle of the PCV pipe in addition to the first one in the middle of the air breather hose to prevent any oil or mist from getting into my intake.

Am I on crack or do I have it right???

More importantly, what should I do? Reconnect the PCV system completely stock, use one or TWO catch cans? Do I use valve cover breathers also?

Or if I don't resintall the PCV system what do I do? Just run breathers? This shit if confusing. I get the need to vent crankcase pressure - great. Yes I don't watn my seals no blow. I also don't want any crap or oil ever making it to my intake plenum or TB. So what the hell do I do???

[mjr_350]

Hey Sarge

Have a quick question for you

Ive done everything you did in your original post plus a little more

My question is, can you vent too much?

Ive hooked both rocker covers up to a T piece at the rear of the engine and vented there with a small filter.
Ive also got a filter on the oil filler cap.

Will I benefit at all from more vent points or is one for each rocker cover enough? It will keep the law off my back a little bit more if I only vent the rocker covers via their rear outlets to the little hidden filter at the back of the motor and install the original sealed oil cap. Cops over here don't like open air filters not to mention vented PCV systems

I hope you understand what I'm trying to get across

[ne0fiend]

Hey Sarge

Have a quick question for you

Ive done everything you did in your original post plus a little more

My question is, can you vent too much?

Ive hooked both rocker covers up to a T piece at the rear of the engine and vented there with a small filter.
Ive also got a filter on the oil filler cap.

Will I benefit at all from more vent points or is one for each rocker cover enough? It will keep the law off my back a little bit more if I only vent the rocker covers via their rear outlets to the little hidden filter at the back of the motor and install the original sealed oil cap. Cops over here don't like open air filters not to mention vented PCV systems

I hope you understand what I'm trying to get across

Well seeing as Sarge is off in Russia finding him a new wife, I'll slip you my two cents.
When it comes to open-air venting, there is really no set standard. By that, I mean everyone's results are slightly unique and dependent on a number of factors;
Ignition system and control(lers),
Fuel management system.
Ambient air humidity and temperature, etc.
Excerpt:
On late model vehicles with computer engine controls, the engine management system will detect any changes in the air/fuel mixture and compensate by increasing or decreasing short term and long term fuel trim (STFT and LTFT). Small corrections cause no problems, but large corrections (more than 10 to 15 points negative or positive) will typically set a lean or rich DTC and turn on the CEL, MIL.
Of course this scenario is a-typical according to mods and fuel type itself.
In short, positive gains from OAV (open air ventilation) are easily obtained no matter to what extent you take it.
A little is good, a lot is great (when coupled with subsequent support; tuning, mods etc) and too much is is a measure you can only ascertain from trial and error.
If you're uncomfortable with fooling with the system and its components, you can find a basic write-up HERE

Hope that helps!
-Marc

[nyarsulik]

Without using a catch can, or a oil breather filter cap, would I be able to accomplish the same thing by simply using breather filters on both the driver and passenger valve covers, and then capping the pipe going into the intake (where the PCV valve used to lead into)? Aside from oil vapor on the engine, would there be a negative effect doing this?

I have a 99 ls1 TA and have experienced the dreaded melted hose around the PCV valve. I don't want to replace the stock system and can't afford a catch can. I tried the generic fix using parts from Home Depot (basically rebuilding the stock system with hose and a t-junction) but I think I am still having issues with the tubing getting filled with oil foam and not burning off... My car has been hesitating ever since the first meltdown and feels like it has lost some power, so I am hoping there might be an inexpensive fix for replacing the current pcv setup.

Thanks!
Nick

[Firebirdjones]

That's how it's always been done back before PCV's were invented. It'll work, so long as you can get past the inspection police.

[TerribleTed]

I made my own catch can out of some white pvc tubing,,,some brass fittings,,and some internal stuff mesh stuff,,,and my can has a drain plug on the bottom,,less than 10 bucks,,and works great...It dont look shiny,,but it works,,,Hardware store for all the parts..

Can length is less than 5 inches,,,and for my semi hard drving on the road for say 3000 miles of time,,it catches like 2 table spoons of oil at the most,,and it is able to catch all the oil and much of the vapor,,but not all thats for sure

[nyarsulik]

That's how it's always been done back before PCV's were invented. It'll work, so long as you can get past the inspection police.

I won't need to worry about inspections any time soon, I am just wondering if there is a big benefit. I think Sarge said that by not shooting the fumes back into the intake you are getting a cleaner fuel/air mixture... Hopefully this would make my car run a little better

[Firebirdjones]

I won't need to worry about inspections any time soon, I am just wondering if there is a big benefit. I think Sarge said that by not shooting the fumes back into the intake you are getting a cleaner fuel/air mixture... Hopefully this would make my car run a little better

Sarge is right, the intake charge will run cleaner without the PCV and just installing valve cover breathers, since you are assentially venting it to atmosphere at that point.

A positive crank case vacuum can also be a good thing though. It rids the crank case of HP robbing pressure. Albiet a small amount that isn't noticed on most street cars anyway.

[Bouvers]

Hey guys, I was hoping you could help me out real quickly. A few years back I installed a RevXtreme Catch Can, I've been pleased I've been catching some crap in there so it must be working. However, when I installed it the instructions portrayed the inlet coming from the passenger side valve cover. Not the Valley Cover. Is there any reason to go from the valve cover rather then the valley cover? Maybe I'm not understanding something. I'll take a closer look at my car tonight. its an 01 if that makes a difference.

[tatertot91]

Hey guys, I was hoping you could help me out real quickly. A few years back I installed a RevXtreme Catch Can, I've been pleased I've been catching some crap in there so it must be working. However, when I installed it the instructions portrayed the inlet coming from the passenger side valve cover. Not the Valley Cover. Is there any reason to go from the valve cover rather then the valley cover? Maybe I'm not understanding something. I'll take a closer look at my car tonight. its an 01 if that makes a difference.

What you're seeing is done with an LS6 valley cover, fbodies didn't come with this but many such as myself have upgraded to the newer style to prevent oil consumption. You're fine off the valve cover.

[Bouvers]

What you're seeing is done with an LS6 valley cover, fbodies didn't come with this but many such as myself have upgraded to the newer style to prevent oil consumption. You're fine off the valve cover.

well sorry to beat this to death, but I'm not quite catching something. Whats the benefit of going of the valley cover rather then the valve cover if you have the option?

[katelyn2005]

yes

[tatertot91]

well sorry to beat this to death, but I'm not quite catching something. Whats the benefit of going of the valley cover rather then the valve cover if you have the option?

less oil consumption through your PCV system. A catch can will catch oil vapors leading to the intake, but the newer style PCV minimizes the vapors before they even get to the can

[zmg00camaross]

I just going to run a line from both valve covers to a vented catch can and be done. plug up the TB.

[Bouvers]

I just going to run a line from both valve covers to a vented catch can and be done. plug up the TB.

This was exactly what I was going to ask. I drew up a quick picture I was hoping someone could tell me if this will work or not. Main points in picture;

-LS2 Valley Cover.
-RevXtreme catch can (main).
-Smaller inexpensive catch can (secondary).
-I want to keep my oil cap an oil cap NOT a vent.
-cap off throttle body inlet.

Please let me know if this will work for venting, should be around 550rwhp NA if that makes a difference.

[Bouvers]

seriously guys, nothing, no one has any input at all?

[Sarge]

I have the catch can hooked up the same as your diagram and the rear drivers side vent running through a breather. Instead of a 2nd catch can I just have a inline seperator from Home Depot prior to the breather.