i wish i knew about that little thing from flyin miata, but i already got the catch can, so i want to use it and if it does fill up with oil i will know for sure that i have a lot of blow by.

pressure builds up in the crankcase as a little blowby seeps past the piston rings. the stock setup takes this positive pressure (along with oil vapor) out of the crankcase and reroutes it back into the intake stream to conform to EPA regulations since venting to the atmosphere is considered harmful to the environment. this oil vapor can cause detonation as mentioned. thats why we use catch cans to trap it. venting the catch can to the atmoshpere is the sure way to take the positive pressure out of the crankcase and make sure none of the vapors make it back into the intake. Actually, you could technically just leave the two ports on the valve cover open, uncapped, but you'd have oil all over you engine bay.

Yes, I was talking about the little filter on the catch can. you need to replace it when it gets saturated in oil because if the pressure can't escape it'll build up in the crankcase and blow your oil seals.

Thanks for this good explanation. Sooo, i will drill a hole in the PCV valve and route both of the port on the valve cover into the catch can and cap the port on the intake.

that should work

Really?

In all seriousness, I've never considered this, nor can I recall hearing it before now. Is the basis of the argument that oil vapor is more prone to autoignition or detonation in the combustion chamber than atomized gasoline?

the only thing i want to get rid of is possible smoking.

This is how i have mine setup.

Attachment 204507

Seriously, you never heard it before? That's the reason catch cans exist. Maybe thats why hustler is getting away with more advance compared to others

smoking? from where?

tailpipe

i see. so you left the pcv valve intact and only routed the right side of the valve cover into the catch can, right? Do you get much oil accumulation in the can?

if you're smoking at the tailpipe you may have other issues.

sbk, you have one side done, but the pcv valve is still sucking oil into the manifold under vaccum, that eventually makes it to the motor next time you boost.

yeah i know. I bet my rings are worn out a bit. But having a catch can would only help in this case.

Rushin, leave it how you first had it, but drill out your pcv valve. the end. That's all Hustler was trying to convey.

I'd at least take the filter off the top and run a hose to the intake pre-throttle body. This way any crankcase pressure get's sucked out rather than having to be pushed out.

no, that would pressurize the crankcase. for the venturi effect you're speaking of, the hose would be routed from where the filter is, to the turbo intake hose

Oops, I meant to say pre-turbo.

if you're hardcore, you can get the same venturi with no drawbacks venting at the exhaust

http://img269.imageshack.us/img269/923/bernoulli5ae.jpg

I ended up getting a 1/2 inch to 3/8 reducer instead of the PCV valve and routed the hose to the catch can. I am still thinking if instead of the filter i should route a hose to the pre-turbo nipple i have on right after the intake filter.

i tried it that way (drilled out pcv) but the car had a little stumble when pulling away from a stop. felt fine when accelerating etc.. but i just switched it back to sbk's style and it's smooth again. my catch can does get alot of oily/watery discharge in it after a trackday though.

did you do it like this?

http://boostedmiata.com/technical/catch_can.jpg

if this causes stumble you have either an airflow meter or you did it wrong.