Gripenfelter

Which is better horsepower wise?

I have a 383 with a fair size cam and a 110 LSA putting out 400+rwhp.

Injuneer

You would be foolish to run without a PCV system. It removes harmful vapors, inculding water from the crankcase, so it doesn't contaminate the oil.

This can be accomplished several ways... 1) use the stock system - it works fine on my 800HP nitrous setup, no loss of HP; 2) use a vacuum pump system - you would need to select and fit the pistons and rings to take advantage of the vacuum to make HP, and a belt driven pump will use up some of the HP you save. Too complicated for a street setup; 3) run lines from the valve covers to the header collectors, allowing the vaccum pulled by the high flowing exhaust gasses to evacuate the crankcase - really a race only setup; 4) convert to the system they used for 30 years before someone dreamed up the closed/positive crankcase ventilation system - install a "draft tube" to develop a vacuum using the high speed air flowing under the car.

In all practicallity, you can't beat the stock system, and it isn't costing you any HP, unless you have a poorly maintained system that is causing oil to be pulled into the PCV valve or to flow back through the air supply tube to the throttle body. You can alleviate oil flow problems to the TB with a breather, or using the Deutsch PCV oil filter in the air supply line.

TQdrivenws6

So what about using a monoblade with no PCV provisions? Are the side effects of running a breather really going to be that great?

Gripenfelter

Thanx Injuneer. I don't have a PCV anymore since I switched valve covers. The PCV tub fit very loosely in the hole so I slapped on a breather instead. I'll find a way of putting the PCV back on.

Injuneer

Both of the above posts seem to indicate you are confused. The PCV valve is not in the passenger side valve cover, and the PCV valve does not connect to the throttle body. What you appear to be confusing with the PCV valve is the air supply line that runs from the throttle body to the passenger side valve cover. That is only an air supply line, and the intent it to feed air that has passed through the filter and the MAF (94+) sensor into the crankcase so it can be pulled through the engine by the PCV valve, which is located on the drivers side of the intake manifold.

In the 93/94 models the PCV valve plugs into a hole at the lower part of the manifold, and discharges into the upper part of the manifold via a short "u-bend" hose. On the 95-97 models, the PCV valve is still in the same location, but the discharge is routed to the front of the intake manifold, to a small port directly below the throttle body.

You can add a "breather" to the passenger side valve cover, to eliminate the line that connects to the throttle body. That will not hurt anything. A slight "vacuum leak", but the long term fuel corrections can take care of that. The 93 won't have that problem, because of not having the MAF.

atljar

Somewhat off topic...
But i dont have the lt1 intake anymore, converted to single plane.

I see myself as having two options...
One, running two valve cover breathers, one on each cover.

Two (let me see if i have this right)
Run a breather on one valve cover, and on the other cover put a PCV and then have it hooked to a vacuum source. Correct?

I like option two personally. Can someone (fred?) reccomend a PCV valve for me? from what i have read they have different operating vaccuum pressures before they click open. Right now my motor is pulling about 14 inches at idle. I would like a PCV valve that i could just fit into the stock size breather hole. I see a few that will fit at summit, but wondering if i need to worry about vacuum ratings for them?

EDIT: Would i want to run a breather on one cover/pcv on other, or PCV on both covers?

93turbo5oh

my buddy had a problem on his NA 5 liter with sucking oil into the intake manifold thru the PCV system. the only way to get rid of it was to eliminate the PCV and just run a breather, since he didnt want to run a vacuum pump.

then i read a warning in the brochure that came with a set of total seal rings i bought. it said that motors that have really good ring seal will sometimes do this with a PCV system, depending on how the system is hooked up. kind of off topic, but interesting i thought.

tagz

is it safe to run a pcv valve in the valve cover and connect the vacum source to the origonal one i have on a 94?

Right now i have my PCV valve in the stock location, and a breather on both sides of the engine. I was experiencing quite a bit of crankcase presure and thought this would help. I do not know if i am getting blowby, or just had a problem with the PCV system. Right now, the pressure has decreased since i put the extra breather on, a new pcv valve, and a new vacum hose.

The pressure was high enough to blow out a few seals.

Would i be better off pulling vacum from the valve covers? Is this more effective? is there a downsdie to it?

93turbo5oh

if youve got a bunch crankcase pressure on a stock motor youve got bigger problems then just needing a breather.

fastcamz28

I know this has been discussed before so please excuse if I am revisiting an "old" issue. I have my PCV valve in stock location (driver's side on intake manifold as you described) w/ no plans to change its location. On the passenger side valve cover I have kept the hose set-up that runs from the TB to the valve cover w/ the addition of a filter/valve(?) in the valve cover. In addition, I have breathers on BOTH valve covers. Partly this is for car shows (valve covers, etc are chrome), but I am now concerned that I may be messing things up from a performance/operational standpoint by having the 2 breathers in the valve covers. Please advise.
Thanks!

Injuneer

fastcamz28:

You aren't hurting anything with a "breather", nor with two "breathers". It is possible that under some conditions, such as under high intake air flow, you might see a small vacuum on the line coming off the TB, and that would pull a little air in through the passenger cover breather, and out the air supply line to the TB. It shouldn't be a lot of air flow through the breather, because you shouldn't see much vacuum at the port in front of the throttle blades that the air supply line connects to, unless you had some sort of restriction to air flow between the air filter and the TB.

atljar:

You should be fine with a PCV (with vacuum connection) on one valve cover and a breather on the other. That will cause air to flow in through the breather, through the crankcase, and out the PCV valve, which should take care of the vapor buildup. I would just use a "stock" LT1 PCV valve, and a grommet that will allow it to fit into your valve cover. I run the stock valve in the stock location, and see similar vacuum levels that you have at idle (13-14"Hg). So far I have had no evidence of any pressure buildup in the crankcase.

aintno6

Im currently running this setup. Autozone had the baby in stock and it was cheap http://collop.cz28.com/custom2.html

atljar

Thanks for the response fred and aintno6.

fastcamz28

I second that!! Thanks for the explanation and assurance, Fred. I have alot of respect for your knowledge and the way you dispense it.

aintno6: that is the same set-up I run along w/ the 2 breathers in the valve covers.
Thanks!