So I have succomb to the need for a catch can, and a vented one at that. Can you guys point me in the right direction for a decent inexpensive one with dual ins and a single out. I am thinking I am going to go from the LSJ VC nipple and the oil cap port TO the can, and draw a vaccum through the brake booster line which will always be under vaccum from the blower.

From what ive read on CSS you want one or the other.

Runt it vented or a closed system. Some guys were saying to block the pcv port in the head under the intake manifold and run a baffled catch can to the intake tract.

Im not sure why you would want to block the pcv port though. But it makes sense why you don't want it vented to atmosphere cause then it wouldn't pull a vacuum at speed.

This is a catch can I read about that is a decent price
http://www.saikoumichi.com/

And Moroso makes a nice baffled can.
http://www.jegs.com/i/Moroso/710/85497/10002/-1?CT=999

So I have been doing alot alot alot alot of reading on this subject.

I have come to the conclusion that the port in the head that we cut our manifold gasket for is not needed. If we plug or cap this port somehow, and move our vaccum source from pre TB to post TB, and run a catch can, we should be able to see enough vac to evac the system properly.

So basically, go from the VC nipple to a catch can NON VENTED, to the brake booster line, all should be well...what does everyone think?

Bingo....

Thats what ive come to the conclusion of as well.

Although im not sure of the reasoning yet of blocking the port just yet.....any links to the reasoning?

Philly, that port in the l61 head works with the stock manifold to let the vaccum created by driving pull crankcase gasses from the case. While us boosted guys are just cruising, it is doing the same thing for us (if you cut you manifold gasket). BUT if you are boosting, and the "check valve" that some say is built into the LSJ manifold is bad, you are essentially pressurizing your crankcase "on purpose". Which will cause issues. Basically you are reversing the system. So if we block off that hole in the head, it doesnt allow us to pressurize the system any longer. Now you will have to run a catch canned line from the valve cover nipple to a spot POST THROTTLE BODY that see vaccum and evac the system that way.


no i could be 100000% bass ackwards on this, and if i am i need someone else to chime in and let me know. but i have blown 2 rear main seals in 7 weeks, and the ONLY reason i can see for this is too much crankcase pressure and i am positively pressuring the case accidently on purpose. to me this mean the "orfice" or "check valve" that is supposedly built into the LSJ manifold is bad.

EvoFire wrote:Philly, that port in the l61 head works with the stock manifold to let the vaccum created by driving pull crankcase gasses from the case. While us boosted guys are just cruising, it is doing the same thing for us (if you cut you manifold gasket). BUT if you are boosting, and the "check valve" that some say is built into the LSJ manifold is bad, you are essentially pressurizing your crankcase "on purpose". Which will cause issues. Basically you are reversing the system. So if we block off that hole in the head, it doesnt allow us to pressurize the system any longer. Now you will have to run a catch canned line from the valve cover nipple to a spot POST THROTTLE BODY that see vaccum and evac the system that way.


no i could be 100000% bass ackwards on this, and if i am i need someone else to chime in and let me know. but i have blown 2 rear main seals in 7 weeks, and the ONLY reason i can see for this is too much crankcase pressure and i am positively pressuring the case accidently on purpose. to me this mean the "orfice" or "check valve" that is supposedly built into the LSJ manifold is bad.

That Makes sence. I wish I was able to see this check valve. Easiest way to block it off would be using a new intake mani gasket, but might as well do the phenolic spacer while your at it.

I cant see why it would make a difference though if your post or pre tb. Either way your going to pull vacuum upon acceleration.

That has been my recommendation for a while now. Block the port in the head with a new gasket and then add as many ports as you can to the crank case and valve cover and run them to a baffled catch can and then to a good vac ONLY source. Running it to the manifold with a check valve is well and good but at that point it closes up during boost which is when you need it most.

I have setup a dual check valve setup as the manifold will see more vaccum at idle and cruise and then shut while another opens at boost but to be honest it's complicated and really not needed unless you're into really high boost, I only know of 2 members that required it and the system worked.

I would love it if somebody like PJ could confirm the check valve that apparently is in the head on an eco. On the LD9 it's just a port down to the air/oil separator.

-Chris-



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