[jj2473]

I got a CHP street Fighter 331 with a ATI D1 supercharger (10 lbs) with about 1000 miles on it. I am experiencing blow by out of the valve cover breather under boost. Is this normal??? or are the rings not seated or shot?

Thanks,
jj2473

[beheivjer]

sounds like a ring issue to me but have you done a compression test to see whats happening

[neverfastenough1]

Crankcase pressure builds under boost. I am pretty sure the pcv valve closes under boost, which means the pressure goes out the breather instead of pulling fresh air in. It is common to blow gaskets and push oil thru the breather. I would look into adding another breather on the other valve cover, or there are catch can systems out there to run hoses from each valve cover to the catch can. I would research this before I decided it was my rings. We got a couple guys on here running boost that will probably be on later. I don't think they are running that much boost though. Hopefully they will have some input. Welcome to the site.

[nolife]

This may sound obvious but you either have too much pressure getting into the crankcase, have a poor oil baffling design in your valve covers, or a combination of both.
A few things you can check

Baffling:
- Does your valve cover have a baffle under where the breather spout attaches? Are those valve covers known to not stop oil effectively on a boosted engine? I don't know of any specific models myself that are good or bad, I have the plain old Ford Motorsport stamped covers and they seem to currently baffle the oil fine on my car.

Pressure:
- A compression check would not hurt and at least eliminate the rings as a source. A lot of work but that will provide you piece of mind and give you some baseline readings to use in the future as your engine ages.
- Is your PCV working good? It may be junk and not blocking the pressure from entering in that direction under boost, the PCV should seat (close) when the engine is under boost. If not, it is either broken, or your crankcase pressure is higher then your boost pressure, which I think would be bad right?

Like neverfastenough said, two breathers seems to work for some people but not if your valve covers do not incorporate an effective baffle design and not as a band-aid for a pressure problem.

[Stangzilla]

Chances are if you put a second breather on the other side and be sure the valve cover baffles are of a good design you should be ok. Also like they mentioned b4 those oil separators work well... Even if you get the seperator still put in the second breather..

http://www.steeda.com/products/steeda_oil_separator.php

[JOEYD0730]

are you blowing smoke or oil out of the breathers? i blow some light smoke out of the breathers in my 331. i dont not have a pcv system with the spyder intake so i am running two breathers.

[Stangzilla]

Originally Posted by JOEYD0730 are you blowing smoke or oil out of the breathers? i blow some light smoke out of the breathers in my 331. i dont not have a pcv system with the spyder intake so i am running two breathers.

I also have a Spyder intake on my 347 N\A motor. With my 11:1 compression I get a little blow by. I took off my Spyder elbow drilled and tapped it and hooked up the PCV system now it works great..

[cali 5.0]

i'd do a leak down test