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Guest INASNT
Originally posted by dabigbolf

inasnt whered u get yours how much?  and is having it venting to atmosphere better or worse.  as i see yours dont have the filter on top.  still looks neat though.

i actually bought it off some1 on here!

if u want to vent it to atmosphere then all u gotta do is drill a hole in the top and insert a filter on top.

hehe,

i'd think not.

from what i have gathered it just makes the air go out easier.

some just have a little hole, but the venting one, vents more.

i think heard someone say they lost a litre of oil due to one, on track day on the vl turbo forums.

but that would have been fullstick non stop for 5 or 10 minutes of laps.

The difference between a catch can, and an oil/air seperator is that a catch can simply collects the crankcase fumes, grabs the oil out of it, and lets the air go. It would theoretically fill up with oil eventually and need to be emptied. An oil/air seperator is the same thing, except that it has an oil drain back into the sump, thus reducing the maintainance level, and ensuring that you don't run low on oil in situation where the crankcase may be breathing heavily ie. track use.

For both devices, the vented air can be routed back into the intake (where it originally went anyway) as it should now be free of oil, and this will eliminate any possible legal issues with emissions etc. At minimum a filter should be fitted because a) the catch can/seperator won't be 100% efficient, so there will still be *some* oil vapour in the air, and B) the crankcase can breathe both ways, and you don't want to be drawing unfiltered air into the crankcase.

Hope that clears it up a bit.

Belly_up - thanks for distinguishing the difference between a catch can and an oil/air seperator. I've been looking into buying one & I didnt think that there was a difference - now I know. I guess the oil/air separator would be more 'acceptable' to EPA as it is plumbed back?

Either of them can have the *air* outlet plumbed back, and thats what the EPA would be worried about.

The advantage of the oil / air seperator is that you keep your oil in the sump rather than collecting it in the catch can. As i said above, it's really only going to be a issue for prolonged high RPM use, not so much on the street.

And when shopping, the two names are used interchangeably by most people (and rightly so, because a "catch can" is acting as an oil/air seperator), so check for whether the particular item has an oil drain fitting, to determine whether it is what you want or not.

This is from the Autospeed article "Pots and Cans... Step-by-step fabrication of swirl pots and catch cans/oil-air separators..."

ASE offers two different products to prevent blow-by oil entering your engine's air intake - a catch can and an oil-air separator. What's the difference, you ask? Well, a catch can receives blow-by oil and allows fumes to vent to atmosphere after being filtered. On the other hand, an oil-air separator internally filters the blow-by oil and allows only clean air to enter the car's induction system. This is the favoured approach from an emissions and legality perspective, but it doesn't look as siik when you pop the bonnet
  • 2 weeks later...
Originally posted by DennisRB30

If you get rid of the PCV system your engine will build up harmfull acidic gases which contaminate the oil reducing engine life.

I just got rid of my PCV and vented it straight to the Atmosphere. Is this bad? or is it only bad when you block it of completely. I'm finding alot of oil and shite in the intake. Never really known about the PCV, lol.

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