Deleting PVC System..........

Any thoughts/feedback on deleting the entire PVC system?

Pull off all the hoses, run a breather off the rear drivers side hose & put a breather in the left side oil fill. Put caps on the passenger side valve cover on the front & rear vents & cap off the throttle body.

Thinking this would keep oil misting out of the intake & throttle body plus eliminate the need for an oil catch can.

I think some sort of positive crankcase ventillation does a better job than just venting.

"Breathers" don't do much of anything, other than allow the pressure to vent out of the crankcase. The crankcase is still going to be full of blowby gasses, that will condense out water, contaminating the oil.

Even back in "ye olde days" when I tore down my first SBC.... the SBC engines were equipped with "draft tubes" to promote air flow through the crankcase to remove the contaminents. The tube stuck down under the engine, in the air stream that flowed under the car, and the air, moving perpendicular to the tube, pulled enough vacuum to suck the crap out of the crankcase.

I don't know the details of the LS1 - is it common to find oil in the throttle body and the intake manifold as a result of the PCV system? I know its a problem with the throttle body on the LT1's, but not much of a problem at the outlet of the PCV valve.

I don't know the details of the LS1 - is it common to find oil in the throttle body and the intake manifold as a result of the PCV system? I know its a problem with the throttle body on the LT1's, but not much of a problem at the outlet of the PCV valve.

Yes it is. I just helped a buddy diagnose the problem with some of the tech guys in the LS1 section.

Recently he did a cam and head swap and consumed a significant amount of oil (much more than typical LS1 usage, "low oil" light 1500 miles after a change".

Difficult to diagnose if you don't know to check the valve first. Slight hint of oil in the exhaust + quick consumption = fear of worn ringlands.

I'm glad it turned out to be as simple as replacing the valve. But if you don't know where to check first, it can get your mind going on "worst case scenarios".

But I see your point Fred, it would seem to do more harm than good to find a way to bypass/remove the system.

Just trying to learn..................if the entire PVC system is removed, than what contaminents would be drawn into the crankcase?

Combustion chamber gasses get past the rings, includes water vapor and all kinds of nasties that will form acids when they combine with the oil and water. Your oil will get "worn out" and contaminated quickly.

Try it, if you don't like the results what have you really hurt?

I don't run a pvc on my LT1, just a breather. I have a modified lt1 vacuum pump I've been wanting to try however I hate to add weight.

As long as you get your engine up to temperature you'll burn off any moisture in the crank case and your engine oil will be okay. If you get that much moisture to do any harm you have much larger problems.

Yes hot oil wil vaporize the water BUT without the PCV is is not pulled out of the crankcase. Yes a breather is better than a sealed system but think of it this way. What cools the house better open windows or open windows with fans or a breeze forcing airflow??

Why isn't it pulled from the crankcase? Hot air vapor rises, it doesn't fall or stay put in the block, it will rise up and exit at the highest point (read, breathers). If you run a sealed system this vapor will build and find another place to exit (seals, gaskets).

You can keep your pvc and keep shoveling contaminated air into the intake tract, I'll run a breather set-up and if I need more I'll run a vacuum pump.

It isn't "pulled" from the crankcase because there is no vacuum pulling it out. Yes, as blowby enters the crankcase, the pressure will build and vapor will flow out of the breather. But the crankcase is still full of that vapor, but now its at atmospheric pressure. As the engine cools down, the water vapor condenses and enters the oil. Some of it will form sludge and acids. Some of it will be driven off the next time the oil reaches normal operating temps... but not all of it, because acids and sludge don't necessarily vaporize at 220*F.

If you are concerned about "contaminated" air getting into the combustion process, connect the PCV valve to one of the exhaust primaries, perpendicular to the tube, and let the Bernoulli effect pull the vapor out of the crankcase, and fresh air in through the breather.

If I had to choose between a few grams of acid circulating in my oil, and a few grams of water vapor entering the combustion chamber, it wouldn't be very hard to choose.

As the engine cools down, the water vapor condenses and enters the oil. Some of it will form sludge and acids. Some of it will be driven off the next time the oil reaches normal operating temps... but not all of it, because acids and sludge don't necessarily vaporize at 220*F.

if I had to choose between a few grams of acid circulating in my oil, and a few grams of water vapor entering the combustion chamber, it wouldn't be very hard to choose.

Do you honestly think that the pvc system is that perfect that it eliminated all this vapor is removed from the engine? What happens when you shut the engine down and now that vapor has no place to go in the sealed pvc system?

Neither are perfect ways, vacuum pump is the best, then I rate breathers next, then pvc and nothing last in a performance application.

Do you honestly think that the pvc system is that perfect that it eliminated all this vapor is removed from the engine? What happens when you shut the engine down and now that vapor has no place to go in the sealed pvc system?

Neither are perfect ways, vacuum pump is the best, then I rate breathers next, then pvc and nothing last in a performance application.


Makes sense........................................What is the proper way to install the vacuum pump method?

If you have PVC on your engine, I would definitely remove it.

PVC has a pretty low melting point, so it could make a big mess.

If you have PVC on your engine, I would definitely remove it.

PVC has a pretty low melting point, so it could make a big mess.

HA!

...

I'm using a crankcase evac system, that I had on my ole race motor.. It seems to get the job done.. you just have to drill 2 holes into your header collectors, and put a tube in @ a 45 or so degree angle (going with the exhaust flow) then run a couple lines from your valve covers and it sucks it all out... I need to buy new valve covers so I can get both sides going..right now I only have one hooked up..but here is a an older photo

On the tb ect.. I just capped them off.

http://www.pbase.com/brahm/image/63244922.jpg

and here is the kit I got.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=MOR-25900&N=700+-115780+115&autoview=sku

You can quibble all you want.... its obvious that the PCV system is superior to a simple breather. The draft tube used in the 1950's was better than a breather. But its your engine... run it any way you want. :D

And I'll run mine with the stock PCV system.

Nothing is obvious, How many top engine builders include them on race and performance rebuilds? How many competitive circle track engines don't have 2 breathers on them? How many times have you dyno'd an engine with and without and compared the dyno findings?

I have every oil change sampled by Amalie Oil, and it comes back with a clean bill of health everytime, there is no mention of "acid" contamination or dillution in the report.

I don't want stating facts be confused with fighting. Back to the original question, try it you can't hurt anything by trying something. Don't be fooled by thinking it is only water vapor exiting the pcv valve, it is part of your vehicles emission system, not a performance enhancing item.

I have used the pcv and stock LT1 crankcase evac system with a FI 383. I always had dirty oil and oil in the intake manifold. Most oil resulted under high load. I then did a full external vac pump system (winter of 07 - vp103 pump). Sealed the engine and regulated to 1/3 atm vac. Result... The oil is alot cleaner, better ring seal and increased cylinder pressure which was alot of unexpected fun. It was not an easy modification since I had to move the rad forward, and, design pump mount inside a 97 engine bay with FI (not alot of extra space in there). Alot of pressure is generated inside the crankcase from the rotation assembly. You need some type of system to vent the positive pressure. The e-vac kits are good, but, are only effective under high exhaust fluid flow.

I have every oil change sampled by Amalie Oil, and it comes back with a clean bill of health everytime, there is no mention of "acid" contamination or dillution in the report.


Interesting................another IMPORTANT aspect of this discussion that I never heard tested before.......................Sounds pretty convincing to me...............

How long you leave the oil in the motor?

One race night on the circle track with breathwers is WAY different than even a week of daily driving.

I raced and drove my car off and on from the end of May to end of July. Granted it is not my daily driver but it gets out at least 3 days a week and driven around. I also drive my car to the track, race it, then drive it home.

I use full synthetic oil (greatly cuts down on crankcase contamination) and I run a quality filter.

When I park my car for the winter, I change the oil, prime the system and leave it.

How does synthetic oil cut down on crankcase contamination???

Now if you had said synthetic copes with crankcase contamination better you might have had a point, but that is not what you said.

dino oil breaks down easier and has un-uniform size particulants during the combustion process these smaller particles break down and can become air borne contaminants. Synth oil does not break down as easy. Thats why you cannot use synthetic oils if you would ever use recycled oil in oil burning furnaces or mixing it with diesel fuel in a diesel engine, it doesn't like it trust me I know.

I'm not an expert on oil, its properties or anything else for that manner. I have been lucky enough to be affiliated with a great race engine building facility for the last 20 some years. We done testing for several oil companies and oil additive companies over the years for our research and sometimes for thiers. I can tell you which oils work best when mixed with nitro (dry sump sprint car application) and which oil additives are snake oil and do nothing. We currently have 2 NASCAR 358" yATES engines running a computer controlled cell for 24 hours a day for MAJOR oil company testing a new oil for thier race teams. I'm just trying to relate my experiences with you and not trying to offend.

The thread has drifted far away from the purpose of the original poster's question. He isn't driving a dedicated race car.... looks like a daily driver, with well done heads, cam etc. Highly specialized racing engines need highly specialized crankcase evacuation components. Putting a vacuum pump on a race motor makes a lot of sense. Putting one on a street driven car certainly would provide a better crankcase evacuation system, but would be over-kill. As Brahm showed, the exhaust driven crankcase evacuation systems have been the low-cost solution to crankcase evacuation for many years. But they are not practical on an EFI setup with cats and O2 sensor feedback. Totally deleting the PCV system on a daily driver, without replacing it with something better is counter productive. I can understand the concern with putting oil in the intake manifold - that's the easiest way to reduce the effective octane rating of your fuel, and get into detonation problems. But at least with the LT1, and a correctly assembled engine, I've had no problems with oil getting into the intake via the PCV system. 8 years of operation, and the hose and the chamber in the top of the throttle body are dry as a bone.

The thread has drifted far away from the purpose of the original poster's question. He isn't driving a dedicated race car.... looks like a daily driver, with well done heads, cam etc. Highly specialized racing engines need highly specialized crankcase evacuation components. Putting a vacuum pump on a race motor makes a lot of sense. Putting one on a street driven car certainly would provide a better crankcase evacuation system, but would be over-kill. As Brahm showed, the exhaust driven crankcase evacuation systems have been the low-cost solution to crankcase evacuation for many years. But they are not practical on an EFI setup with cats and O2 sensor feedback. Totally deleting the PCV system on a daily driver, without replacing it with something better is counter productive. I can understand the concern with putting oil in the intake manifold - that's the easiest way to reduce the effective octane rating of your fuel, and get into detonation problems. But at least with the LT1, and a correctly assembled engine, I've had no problems with oil getting into the intake via the PCV system. 8 years of operation, and the hose and the chamber in the top of the throttle body are dry as a bone.

Yes I'm gonig to have to retract my previous statement.. I put my car to the test this weekend...and failed.. I drove 400 miles from Mammoth to San Diego....it took 9 hours due to complications with the car. Me and 2 of my buddies spent all yesterday trying to figure out what is wrong.. and one of the things we decided couldn't be good for the setup, and caused problems was the way I had the evac system setup.. Now I'm not saying these won't work if you do it right.. but mine was setup wrong, and I really should have thought twice as now it's pretty clear as to why it was a bad idea..

Basically the way I had it setup in my old motor (with no thought of 02 sensors) was I put the evac bungs in my header collectors, which in it's self is fine, but when I went to put my o2 sensors I didn't think of what problems I might have by having the evac ahead of the o2 sensor in the exhaust system. So my o2 sensors are in the exhaust behind the evac.. I believe I should have reversed it.. I can't be 100% sure that it is causing problems for me or not...but I can't see how it can help. I ended up just capping one of them off, and will cap the second one off today.. alot went wrong with the car and I'm trying to elemnate any potential problems 1 at a time.

put the evac tubes after the mufflers. make sure to check the valve operation of the evac system if you had issues with it, they can go bad. We've done a few 632" engines that did the entire Power Tour with no issues.

One shop I talked to about this said just about every LT1 they seen with just a breather on and no PVC system developed oil leaks. dont know how true that is but just a thought.

One shop I talked to about this said just about every LT1 they seen with just a breather on and no PVC system developed oil leaks. dont know how true that is but just a thought.

Doesn't just about every LT1 develop oil leaks regardless of the configuration of the PCV system? ;)