Arent those little filters that connect to the crank case vent bad? Theres a long discussion on them on SHO saying that they are bad. What confuses me is why people still continue using them. I click on images of other people's engines and that little filter is connected. Why??????

 

I don't know why people put those on. The tube that goes from your intake pipe to the valve cover lets air into the valve cover to help move the oil vapors out the bottom of the motor into a catch can. The system helps equalize pressure in the crankcase.

 

What is another option on a turboed car?

 

Ok, with a boosted car, everything is a different story.

I too have heard that using a crankcase filter on a relatively stock car is a stupid idea, but for a turbocharged car, you no longer have the tube connecting the intake to the top of the valvecover.
I don't know exactly how to explain it, but it would be too much extra pressure if you connected that hose on a car that was equipped with a turbo.....The point of the filter is to block any splatters of air/oil/junk that will come out of that tube and spurt onto things in your engine bay.

 

What about the question about another option? By the way, I have a valve cover filter on my boosted car.


[Modified by 1, 11:13 PM 12/13/2001]

 

Why would you want to use another option?

It does the job, and looks cool.

 

These engines are supposed to have positive venilation. Which means that the air intake (stock) will suck the air out of the crankcase relieving excess pressure. Technically on a turbo car you should move the tube to the turbo's air intake. Nobody does it though because they are afraid the turbo will suck a bunch of oil out of their motor and gunk everything up. The valve cover (at least on the SOHC) is baffled, so I don't think there's much chance of that happening. If you put the filter on the valve cover, it has to vent itself and no longer has "positive" ventilation.

 

I guess I should let it stock with my JRSC, cause the vacuum is still there. The blower makes preasure after the TB. Correct?

 

Yes, correct...

 

Ok, so when there is a tube going perpendicular into the main air filter, and your boosting, does it see vacuum? atmosphere? boost? does anyone know?

It seems like it would see the same thing the SC does, cuz like the SC the inlet is before the compressor.

 

Use a catchcan.

 

Wow there is some confusion here and some some good info.

Remeber one thing, the air should ALWAYS go into the valve cover and come out through the PCV valve. If it does anything else the system isn't working right.

Best turbo option is a catch-can system.
Second best is a one-way valve on the valve cover so air can go in.
Third best is the little filter.
Last is to run it to the intake to the turbo.

Here is my ranking thoughts: The catch can does all you want. No oil in intake charge and the system is closed-loop somewhat. The one-way valve is great cause it forces pressure into the accumulator and into the intake as it was supposed to, but you need a very sensitive one-way valve and I haven't found one yet (no, fish tank check valves don't work). The little filter helps prevent the oil vapor from backing out the valve cover on high rpm. The last is the run to the turbo because between the turbo and the air filter is a real vacuum source under boost (unlike betwen the TB and the filter on a NA car) this WILL suck oil vapor out of the valve cover. You have to understand where there is atmosphere and where there is real vacuum. In NA apps the tube never sees vaccum short of the drop between TB and filter (very small), but in the turbo app the pressure is much lower between the filter and turbine. The turbine is moving much more air than the NA app so their is a vacuum effect that is appreciable. So don't put it there.

If you really give a damn, use the catch can system. The PVC system is ONLY there for emission purposes and not for power (unless you are running mad HP).

Randy

 

ok how does a catch can system work?

 

so basicly, putting one of those little filters on a turbo'ed B18b is O.K.?
Will it hurt my engine?

 

No its fine if your turbo...but if your NA its gonna cause some troubles in the long run.

 

RGAZ a LOT of what your saying makes sense. My question is: describe what your talking about when you say a catch can. Do you mean a catch can between the crankcase and the intake manifold? If so, how does the air get in the engine: either trough a crankcase breather or a tube to between the filter and turbo.

Also, w/ a slash cut tube, would that prevent the turbo from sucking at the engine when at boost?

 

by catch can what he really means is oil separator, top fuel dragsters have so much + crankcase pressure they plumb the tube into their headers for massive vaccuum to releive all pressure.

 

I'm still confused
I thought that you wanted air to come OUT of the valve cover through that crankcase breather thingy? Isn't that what happens on a bone-stock car with the tube hooked up to the intake, which sees some levels of vacuum?

Also, what's your opinion of just using a long tube that hangs down towards the ground?

 

The air coming down the intake tube is "sucked" into the valve, down through the oil drain oils, then into the vapor seperator on the back of the block. From there the vapors go through the PCV valve then into the intake manifold.

Simple, yet easy to get confused.

 

ALRIGHT!!!, the PCV system, my favorite topic. Those little filters on the crankcase are not bad. That is the intake for the PCV system, the reason it is placed on teh intake tube on a stock car is simply to provide the crankcase with filtered air. When you have a boosted car if you left it hooked up then you would be pressurizing the crankcase. Placing a little filter on the crankcase is the same exact thing as the stock setup.

BTW, mista bone and RGAZ, I applaud you guys, finally someone that understands the PCV system and doesnt just post a bunch of garbage they read on some site. There was a post a couple months ago about this that was just completely ridiculous and I ended up getting really pissed off and yelling at everyone


[Modified by TurboInteg95, 5:38 PM 12/14/2001]

 

hey since you guys are covering the PCV system so well, on a turbo car w/ the stock manifold.. how do i hook the pcv and purge valve up (going to the charcole canister) right now they each goto the intake manifold, but i really dont know if this is right

 

I agree with you Brian on this one. Its the 1st time we have agreed.