fperra

You get flow through the crank case on a NA car because the vaccum in the intake manifold sucks the air out of the crank case and sucks the fresh air in through the front vent on the valve cover. The PCV valve is a cheap one way check valve that only is suppose to open under the partial vacuum created by the engine through the intake manifold.

AllStock27

The front breather pulls in fresh air, when you are not driving it hard.... If you are doing full throttle runs (on an n/a car or boosted car),any excess blow by also goes out of the front breather... check the link i posted a few post ago

Just to get this clear, If you decide to NOT put the krank vent in the front, your car would still run the way its designed from the factory, and with the krank vent in the back, you add one benefit, you prevent boost from entering the krank case.

if you add the k.v. in the front, then you are removing that process of being able to take in fresh air on your crank case during normal driving (which is about 80-90% for me). I guess You decide if its important or not. For me, i haven't seen any convincing arguments to make me remove this important process just for the sake of a stronger vacuum.

and about the dyno HP incrs by having a krank vent in the breather hole, not really sure where this extra HP comes from. Whether you have a krank vent in the front or not, blow by would still flow out of the front breather during full throttle dyno runs....(since the back krank vent is locked in due to boost).

So a setup during full throttle runs, there should be no difference between a car w/out a kv in the front compared to a car w/ the kv.. (assuming both cars hav kv's in the back).. I just got my KV's today, and hopefully if my test pipe arrives b4 wed, i can have a lil dyno to see if all this makes sense. lol

XclusiveAutosports

Don't boosted cars from the factory come with some type of crank vent or check valve system? I guess their must be some benefit from it.

Kremlin

I'm curious to get a set, but I'm basically waiting to see if XViper does it first, haha...

xviper

Nope! I'm happy with my PCV and front breather "T'd" into the same vented catch can. I don't need no stinkin' vacuum to draw out the vapours.

Kremlin

Ah damnation. Maybe if I have time this summer I'll buy a set and do a dyno before/after.

jakub2000

The more I read, the more I'm lost if I should use both of the vents or only the one on the PCV line.
Snce I do not have the secondary vaccum system anymore, surely there wont be any boost entering trough the front breather (because it's not conected to anything).

Does ANYONE have an explanation why the engine should make MORE power when we "increase" the vacuum in the crank case?

I am 100% with you on the "boost in crank case is a no no" thing, but can't follow the "more vacuum in the crank case is good" thing........

xviper

You are still confusing these two systems with each other. It's been posted already but it's worth saying again. The "secondary air injection system" is a DIFFERENT system from the PCV system. The system you no longer have has nothing to do with the front breather or the PCV valve or the Krankvent.

jakub2000

^ I just do not remember where the OEM hose from the front breather went, sorry but I thought it was a part of the 2ndery vacuum system..my bad...and NO I am not confusing these two don't worry. Where did it go on a stock car?Into the airbox?

jakub2000

To sum it up:

1.The carnk case vent on the PCV line is there to block boost from entering the crank case
2.The vent on the breather line is there to maintain this magical vaccum.

Correct?