fxgs

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.

Kevin Blown 95 TA

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

Injuneer

"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.

WheelmanZ28

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.

fxgs

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

96capricemgr

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.

tomcowle

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.

96capricemgr

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??

tomcowle

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.

Injuneer

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.

tomcowle

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.

fxgs

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

sbs

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.

brahm

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.



and here is the kit I got.

http://store.summitracing.com/partde...5&autoview=sku

Injuneer

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.

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