http://www.thunderracing.com/catalog...ories&pcid=287
would that work to do the same thing?

 

Yeah thats what I thought.


So this guy dosent have anything stopping oil from going into the intake? right?

I thought the purpose of the CATCHcan was to catch the oil in the system before it got to the intake

 

YES. Someone FINALLY sees the light on that one. But its not a catch can. The LS6 cover is about the best way to help with the oil consumption. In some cases both the cover and a catch can are used to combat the problem. But after the LS6 cover is on, it usually does the trick. But sometimes, the vent tube becomes a problem. That is the shorter hose on the passenger side of the motor at the valve cover and hooks to the TB. It really is best to plug that bastard and get the Metco breather cap.

 

The intake is plugged off. I was told by several shops on LS1Tech that on the big boost setups, they simply plug the manifold and run the 2 lines from the valve covers to the catch can breather.
From what I understand, the reason for the plug on the manifold is simply to provide vacuum to "pull" air from the valve covers. The problem is that you need a PCV or check valve on that line to prevent boost from coming off the manifold and actually pressurizing the crank case. The real thing Im trying to accomplish is keeping pressure from building in the crank case. Since I have to plug the manifold, I have no issues with oil getting into the intake. Some suggest needing a vacuum source to pull the air/oil through the valve covers and PCV system, but I havent come to any real reason why this is needed. I can see pressurized air coming out of the valve covers and possibly getting some oil into the vacuum source which is usually just preblower or turbo which gives you the chance of having oil/ muck into the impellars and even intercooler.
And Im done. This is all Ive gathered from 3 days of study.

 

The problem with not having a vacuum source on the crankcase is that it is needed to pull out the blow by that occurs in all engines in small amounts. Without a vacuum source the crankcase will pressurize from that alone, although it will be minimal. Having vacuum to the manifold actually helps with power productions especially on boosted applications. The trick is to get the crankcase evacuated under boost which is why race cars run crancase evac systems that scavange through the exhaust. Even while not under boost you still need to pull the leakdown out of the crankcase- it helps with ring sealing, oil consumption, and economy.

 

The way it was explained to me by some guys that are making the big turbo LS1 kits is that blowby is a product of the pistons and ringlands. It is pressure. Why would you need vacuum to evacuate pressurized air/oil?? I agree that getting a little vacuum could only help, but with my setup it would be pretty difficult and of very little added benefit. The way I look at it is how much pressure could really be going to the crankcase with my setup?? I have a 1 1/2 opening on my breather. That would be more than enough to let out all 11lbs or so of boost that Im seeing if it were on the intake pipe. I know b/c the outlet on my blowoff valve is near the same size and it is rated up to 14lbs on a T trim which has a much greater CFM rating than my S trim that is on the truck now. That will change soon though

 

somewhat offtopic but a fellow auto student brought to my attention that gm has a TSB on the pcv valve to replace it with an open orafice tube

-erik

 

I tried that, it didn't work My PCV hose was still filled with oil. Then I installed a homemade catch can that quickly filled up about a half inch until oil started bypassing it into the intake. After that I bought an AMW catch can (luckily before they doubled in price), and so far, so good. I actually went back to the original spring and plunger style PCV valve as the fixed orifice one whistled when combined with the catch can...it was pretty annoying.

 

i have a ebay one works ok...it catches oil...

now my question is why cant we plug off the intake and then run a breather on the Crankcase vent?

 

Ok, well we still dont know how much they are so... Guess they are not for sale...