Do breather's do anything?

[videoman]

Everytime I see a show car I see air breathers on the oil caps. I've wondered, do they do anything or are they just for show?
Can anyone expand on this a bit , offer some info on what they really do.

[GrandAmGT99]

What do you mean on the oil caps? I've seen crankcase breathers before, supposedly they do something, I'm not sure though.

[SnM]

What do you mean on the oil caps?

they are a small little filter that sticks out of the valve cover where you put the oil in.

I have no idea what they are for and I was wondering the same thing too.

[videoman]

Yeah the ones they put on where the oil cap would be. Is there a point for them ?

[qwik99gt]

Okay, I'm just going by past experience here, so bear with me. On my V8, I have a PCV valve on the passenger valve cover and a breather on the driver side. The theory is this: The vacuum generated by the engine pulls airborne contaminants out of the crankcase through the PCV valve and runs them though the engine, burning it off. The filter is on the valve cover to allow fresh, filtered air into the crankcase and keep from having negative crankcase pressure (vacuum). The only reason I can think of as to why newer cars do not have these is that the filters allow the smell (and therefore a small amount of pollution) of the crankcase to escape into the air. I do not think this would increase perfomance or have any effect on our GA's. Hope this was informative. Long live the 625hp ProStreet S-10!!!

[videoman]

Hmm, that did help a bit. I wonder if a breather would affect the air compression inside the engine.

Yeah yeah, more questions but how's a guy to learn.

[qwik99gt]

Hmmm. Air compression? If you're referring to cylinder pressure, no. The reason: the filter is open to the crankcase only (area under the pistons, around the crank, and in the oil pan). After thinking about it, I believe our oil fill caps allow air to pass though anyways, so they work just like the filter. The only thing related to this issue that will increase horsepower is creating high vacuum inside the crankcase with a electric vacuum pump. It is a trick used on full-blown drag cars to increase the Hp by .5-1% (a very small amount). Not really a worthwhile mod when you consider how quickly it causes gaskets to fail and having to seal up your engine. Guess which car uses this technology? GM's flagship hotrod, the C5 LS1 Corvette. I wouldn't expect to see it on any other cars until much stricter emissions are required. Can you tell I race and know a GM engineer or two? heh heh heh. Hope this helps even more.:D

[adorai]

if you are talking about what I think you are talking about then yes they serve a purpose. Every time your piston compresses air/fuel, a TINY TINY TINY TINY TINY amount of the mixture can fly past the seal and get into your oil. Normally it will work its way out of the system on its own through the dipstick or something. However, if you have a REALLY high compression engine or if your seals are bad too much air can get through, and in its haste to escape it can push some oil out with it. If you are talking about what I am picturing in my head, it is a lil filter that will let air escape but not oil.

However, I could be 100% wrong.

[videoman]

Yeah that seem right. So unless you have a high compression system IE Supercharger, they dont help much if any.

They just make it look special?

[adorai]

probably

[Drew99GT]

The PCV system on modern cars does exactly what a breather does, except better. Like someone else said, intake manifold vacuum pulls crankcase vapors out. A breather just vents the crankcase, but won't pull harmful contaminents out. The downside to a PCV is it can gum up the intake tract from the oil vapors etc. That's why you need a catch-can, which is basically a breather system hooked up to a seperate container that has engine vacuum. You get vacuum to pull crankase vapors out and relieve crankcase pressure, but you won't gum up the intake tract.