# Oil catch can with breather cap? (Question)



## Roeville (Mar 1, 2012)

I have a 2006 M6 GTO and I have questions about oil catch cans and oil breather caps. I know the purpose of an oil catch can and while some seem to think it does nothing, I am one of many that sees the benefit of an oil catch can. I haven't ordered one yet, but plan to do so in the future.

I've been doing a lot of research on them and I think I found one I wanted. But I have a question about putting an oil breather cap with it

Now I know one purpose of an oil breather cap is to relieve crank case pressure and is something that is used a lot with forced induction. I've also read that some people delete the PCV and replace the oil cap with an oil breather.

My question is, would there be any benefit or adverse effect to using an oil breather cap with an oil catch can, or is this simply two things that do not go together? 

Though I am not currently forced induction, I do have plans on that one day.

Sometimes I do so much research that it seems to hurt more than it helps and I think this might be one of those cases. I've read through several topics on this but can't find anything specific on the two items together. Any help would be greatly appreciated.


----------



## svede1212 (Nov 1, 2005)

The breather would normally be the air source for the crankcase with the suction side still being the intake manifold. Unlike the stock set up that air would now not be metered by the MAF and would be "extra" air. It's not a huge deal but it is one. I use a breather but run speed density tuned so I use no MAF and the computer doesn't care where the air comes from. A benefit is that with a normal catch can set up you can get oil vapors entering the intake by traveling backward up the "air source" tube. 

The stock system operates on manifold vacuum. When you go WOT you have no manifold vacuum and yet at the same time you have the most amount of crankcase blow-by. The easiest and shortest path is backwards up the air source tube between the MAF and TB thereby completely missing the catch can. 

My system also uses a humongous catch can that I made for under $50 and is hidden under the front bumper between it and the driver's wheel. IMHO it is more effective to the extreme than anything you can buy.


----------



## Roeville (Mar 1, 2012)

Svede, thanks for the reply. I've been reading a lot of your posts over the last several months and I've come to know you as one of the more respected and knowledgeable members on the forum. 

You seem to be quite handy with custom stuff. Do you have any pictures of your set up? I'm average at best with fabrication, so I think personally for me it would probably be easier to by one that was made specifically for the GTO. 

So the breather you have that you mentioned, is it part of your catch can set up or do you have the oil breather cap that replaces the oil cap? 

And with future plans for forced induction, what should I take into consideration when getting these setups. I don't recall ever seeing them on a forced induction GTO, but I haven't seen a lot of them period so I don't want to do anything that I may have to undo later if you know what I mean.


----------



## svede1212 (Nov 1, 2005)

With forced induction you'll need one even more. The one I constructed is extremely easy and is hidden so there's no engine bay clutter. You could probably skip the cooler too. I decided to do an overkill and I'm not totally convinced it's necessary but I already did it.

My weird catch can experiment - LS1GTO.com Forums


----------

