Sr20 crankcase pipe

[91EfSi]

Was curious if this is a needed pipe? Bought an engine awhile back and this fitting wasn't in the block. I have vibrant catch can with AN fittings on valve covers. Ive searched everywhere and no one says if it's needed or not. Can I put a freeze plug in it's place or try to make a new pipe105033

Sent from my SM-G950U using Tapatalk

[nisileighty]

I’ve always hooked mine up to the T on the valve cover then to a vacuum source, best crank ventilation that way.

[91EfSi]

I don't have the T since i have fittings welded on to vibrant catch can. This is how it's been even with my previous setup. That fitting on backside did hook up to my old engines crankcase pipe though. But this engine was missing one. 105034

Sent from my SM-G950U using Tapatalk

[nisileighty]

I’ve always hooked them up, so I’m not sure of the negative consequences of not hooking it up are. Maybe someone more knowledgeable than I am can chime in. Clean setup btw!

[jedi03]

I was blowing out my front main seal with it incorrectly hooked up so I would heavily recommend hooking something up...

[Kingtal0n]

alright ill bite <3 crankcase topics
I also like to simplify things, no big words and easy to understand 'talking'

the crankcase is like a large cup from mcdonalds with two straws in the lid.
the lid is the valve cover. One straw has a check valve (PCV valve).


You find the straw with the check valve first and verify it runs from the crankcase, through the check valve, to the intake manifold. It receives full time vacuum from intake manifold through pcv valve and the pcv valve shuts fully to stop boost from going into the crankcase. Everybody should test/replace pcv valve because if boost goes into crankcase it blows out oil seals and makes a mess.



Second straw has no check valve. Stock sr20 this straw runs to the pre-turbo inlet hose. During engine vacuum situations it acts as an INLET to the crankcase, replacing what straw #1 removes. If you block straw #2 the crankcase will be pulled down to intake manifold vacuum via straw #1 and it will suck in oil seals i.e. front main seal will be pulled into the motor(damaged). So this straw is extremely important, it must stay clear and free of obstruction at all times and is a 'maintenance point' of PCV system (inspection of the tube and cleaning of the tube).

During boost, because the checkvalve is shut in straw #1, straw#2 acts as an OUTLET or VENT instead of an inlet. The pre-turbo (post air filter, post maf) tube 'pulls' on the crankcase to help assist removal of blow-by gasses during boost. The 'pull' is low pressure generated between the air filter and the turbo compressor. therefore, the more restrictive the air filter, the lower the pressure between those two points, the harder the turbo will 'pull' on the crankcase.

Auto manufacturers use a PAPER air filter and a 'smallish' feed the turbo because they have pre-determined that optimal PCV system operation (longest oil life, cleanest oil for reliable cars while driving) occurs when there is an inch or two of vacuum pulling on the crankcase during boost, which scavenges blow-by gasses from the crankcase during boost preventing them from building up in the oil as quickly. It is therefore recommended that if you change the air filter or pre-turbo tubes that you install and monitor crankcase pressure during boost, then modify the filter/tube to achieve a desired crankcase vacuum (low pressure) signal during boost if oil life (engine longevity) is a desirable trait. In some applications they change oil extremely frequently and so this isn't done but is highly recommended for daily drivers.

More reading
https://www.supraforums.com/forum/showthread.php?1043226-pcv-check-valve-question&p=13201033&viewfull=1#post13201033
http://www.nsxprime.com/forum/showthread.php/154972-Oil-catch-can/page6?p=1909388&viewfull=1#post1909388