PCV boost question

Reply Subscribe

Thread Tools

Search this Thread

Jan 30, 2003 | 02:55 PM

#21

mn_vette

Thread Starter

Melting Slicks

Joined: Jan 2002

Posts: 3,293

Likes: 79

From: Jackson MI

Re: PCV boost question (Flame Red)

Flame,

That's what I did and on your first post you said "no" so it confused me. I think I understand now. the suction comes from the drivers side, then why would they have the tube on the pass side got to the TB? Is that just free air that's already been filtered?

Jan 30, 2003 | 03:16 PM

#22

krivera

Drifting

Joined: Feb 2002

Posts: 1,937

Likes: 2

From: Arvada CO

Re: PCV boost question (mn_vette)

Quote:

the suction comes from the driver’s side, then why would they have the tube on the pass side got to the TB? Is that just free air that's already been filtered?

The TB provides vacuum to pull the air out of the valve cover but if I am correct under boost it will do the opposite (blow air and create pressure in the crankcase.
!

Feb 2, 2003 | 12:40 PM

#23

MrNuke

Le Mans Master

Joined: Apr 2000

Posts: 6,341

Likes: 1

From: Shelton CT

Re: PCV boost question (krivera)

Quote:

the suction comes from the driver’s side, then why would they have the tube on the pass side got to the TB? Is that just free air that's already been filtered?

The TB provides vacuum to pull the air out of the valve cover but if I am correct under boost it will do the opposite (blow air and create pressure in the crankcase.
!

Ehhh TB doesn't provide vacuum anywhere..
The TB to Passenger side valve cover 'line' is just a plain fresh air line. Nothing to it. I replaced mine long time ago to clean that side off with a K&N Breather.
The drievrs side is the PCV system that 'should' stay setup as it came. Mine conenct from the lower intake manifold to the PCV valve and Fuel vapor canister for vacuum. I heard if you replace the passenger side with a free breather you'll get blow-by eventually. AS the gentleman put it before, the PCV valve will keep boost out of it, just check it to make sure it is operating good every now and then. Last thign you want is the pcv valve destructing and metal parts inside your heads.
:cheers:

Feb 2, 2003 | 04:46 PM

#24

dgoodhue

Safety Car

Joined: Dec 1999

Posts: 4,691

Likes: 1

From: Framingham MA

Re: PCV boost question (MrNuke)

I woud definately leave the driverside valve cover PCV valve.

On my factory turbo vehicle, their is two PCV valves on one valve cover, one tied to the intake for vacuum and the other tied to intake for boost puposes. The other valve cover is connected to the air box. I have read that you can put one breather on the valve cover that is tied to the air box, but long term effect of two breather will cause blow by. Some people use an electric air pump instead of the 2 PCV valve system.

Mar 5, 2003 | 07:35 PM

#25

Ken Lanham

Instructor

Joined: Sep 2002

Posts: 159

Likes: 1

From: Denver CO

Re: PCV boost question (dgoodhue)

1) Is this car speed density? If so, then the PCV connected to the valve cover is OK. If it is a mass air car, then you are creating a big vaccuum leak by having the baby K&N filter on one of the valve covers.

2) PCV valves only do a mediocre job of keeping boost out of the crankcase. They are not really designed for the purpose of holding back high boost. You can buy a better ball and spring style check valve to put in the line though. Make sure that air flows only into the intake, not the other way around. Grainger sells these valves. I chased crankcase pressurization problems for a long time until I started using good check valves.

-Ken

Mar 22, 2003 | 03:08 AM

#26

gcrouse

Melting Slicks

Joined: May 2000

Posts: 2,148

Likes: 1

From: Chandler AZ

Re: PCV boost question (krivera)

Quote:

The TB provides vacuum to pull the air out of the valve cover but if I am correct under boost it will do the opposite (blow air and create pressure in the crankcase.
!

Congrats Kevin! You're the only one in this whole post that understands what's going on. For the rest of you:
1) TB supplies filtered air to pass side valve cover.
2) Air goes thru the crankcase and is pulled out the drivers' side into the lower intake manifold by vacuum.
3) Under high vacuum (idle or throttle closed) the PCV valve is pulled CLOSED because the extra air plus yucky oil fumes will make the engine run poorly
4) Under low vacuum, (>medium throttle) the PCV valve is wide open as the extra air and oil fumes won't annoy the engine too much now.
5) Under boost, the PCV valve is wide open, pressurizing your crankcase, blowing air out the dipstick tube, back thru the TB, and generally mangling your oil seals (if high boost).

The official instructions from ATI describe this: cap off the TB air outlet (since it's not used); plug the manifold vacuum port with a pipe plug; throw away the PCV; run a breather hose from each valve cover over to the K&N intake on the Procharger. There is plenty of vacuum at the intake of the Procharger to keep a little negative pressure in the crankcase and keep the fumes out of the atmosphere (which was the original reason for the PCV system anyway). You can always just run plain breathers too.

Mar 22, 2003 | 04:34 AM

#27

mn_vette

Thread Starter

Melting Slicks

Joined: Jan 2002

Posts: 3,293

Likes: 79

From: Jackson MI

Re: PCV boost question (gcrouse)

If this is the case, I'll need to cap off one of the sides of the "U" on the drivers side. Does anyone know if the vaccume side is the front or the rear connection on the "U".

Mar 27, 2003 | 03:20 PM

#28

mn_vette

Thread Starter

Melting Slicks

Joined: Jan 2002

Posts: 3,293

Likes: 79

From: Jackson MI

Re: PCV boost question (mn_vette)

OK, just for the fun of it I pulled my PCV valve and blew into the end that would be under pressure from boost and it seems to block it off. When I sucked (not recomended due to fumes and such :crazy: ) like vaccume in the manifold would do it opened way up. So I guess you don't need to do anything with it.