Question,because I don't know everything. And I'm not afraid to admit it.

Valve cover breathers. The type that simplytwist on, in place of the oil filler cap. Are they purely decorative, or are they actually functional? If so, how much do they add to the performance of the engine?

 

I don't know a whole lot either, but I'd think that they would act as a cooling mechanism.. let fresh air into the cavity between the cover and the heads and let all the hot air out.. but I'm not going to put any money on that theory :P

 

I was thinking the same thing, but then I got to thinking about it more. Since it goes in the filler hole, it's only cooling on the one side of the engine. Also, if it was so great, wouldn't more people be doing it? Like race teams, the manufacturers, etc...? People who are serious into cooling the oil, usually install an oil cooler.

So I'm thinking that maybe it's more of a decorative thing then?

 

Never heard of them, but if they replace the oil cap and let air in I'd be a little afraid of getting dirt in my oil.

 

http://www.wbodystore.com/grandprix/...ther-p-31.html

 

You guys have it all mixed up- here's the scoop:

From the factory, our cars come with a PCV valve. This valve connects the pressurized (from piston blowby) crank case to the low pressure intake tract. This allows your intake to suck air out of the crank case and to even get it a pinch below ambient (you want crank case pressure as low as possible, hence why drag cars run a vacuum pump specifically to pump air out of the crank case).

If you install a breather on a car with functioning PCV- your intake will suck the air out of the crank and the standard pressure air through your breather- thus introducing a vacuum leak into your system.

The reason they sell them is for people with the supercharged L67 who do an older intercooler. The old style ones completely blocked off the PCV passage so it could no longer connect to the intake. People had to run a breather, because you would rather have 14.7 psi ambient pressure than to let the blowby gases just build up until it starts popping gaskets to escape.

Its really a terrible solution to the problem- you would much rather have 10 psia (just throwing out a number) in the crank case than ambient 14.7. The best solution is to reroute the pcv so it can connect again- or buy a vacuum pump.


A lot of the old school muscle car guys run these because its more difficult to make a working pcv system on a carb setup, and vacuum pump setups are crazy expensive- so they either run a pair of $20 breathers, or spend $1k fabbing up a vac pump.

So if your factory PCV works, and you don't have a W2A IC plate blocking it off (on your L67)- then you will make more power with it than you will from disabling it to run one of these breathers.

This item does not add power and does not cool the oil.

 

I always ran them on my Firebirds because of all of the blow buy in the throttle body. It would be coated with oil after running hard. There was never a difference performance wise on the dyno with the breather on or it stock. Just cleaner in my opinion. Never had an vacum problems with the pcv in those cases. Don't know if the monte is different or not.

 

Thanks for the info guys!

 

If you're worried about the oil that gets in your intake through the pcv system, then just run a catch can. That still allows the benefits of the PCV system with practically no oil deposited in the intake.

I just think its retarded to disable a functioning PCV system to run a breather- although I've seen a lot of GP guys do it. I think its just because they don't understand the mechanics of it all, and just think it looks cool.

 

That is true on the catch can. I am the type of guy that likes removing all of my emissions related items on my cars. Iremoved all 3converters onmy wrx and my gas milage went up as well as my horsepower. Of course it was tuned and leaned out to use all the available gas. I have never seen any negative effects on my cars, but I also never had them long enough to know if there were any long term effects. On the monte I will leave well enough alone unless it proves to increase horse power on the dyno. I see your point though and it is very valid.