Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 As I said... this topic getting pretty confusing. Dude, you DONT want pressure in your engine. Pressure in the engine is BAD. Pressure buildup in the engine can and will cause oil leaks. Especially in a turbo car, the excess pressure from boosted blowby, if not allowed to vent, WILL blow your oil seals out and probably damage the pan gasket and possibly valve cover gasket as well. You DO want VACUUM in your engine, though most people do not consider it a necessity, it has been proven to help (a very small amount) to free up more power. Using a catch can, you should end up with NEITHER in your engine. With the stock PCV system intact, your block would normally see vacuum at times when your intake sees vacuum, and it uses that to suck blowby from out of the block, into the cylinders to be combusted. Where there's boost present in the intake manifold, the PCV valve closes, but pressure and fumes are still sucked into the intake via the valve cover vent. Either way, with a stock PCV system, correctly functioning PCV system, there should NEVER be pressure built up in your block, only vacuum. Either leave it vented to atmosphere (okay), run a catch can (better, cleaner, but this is STILL vented, only now oil builds up in the catch can instead of on your engine), leave the PCV system stock and fully intact (probably even better, but I dont like the idea of oily fumes being sucked back into the engine, as this can contribute to detonation, plus I dont like all that oil build up in my intake), or run the two vents to a vacuum pump (best, from a performance point of view, but expensive in time and dollars). Leaving the PCV system only partially intact, or blocking off one or both of the vents, or leaving one hooked up and then just leaving the other open, are all BAD, and will result in either vacuum leaks and a crappy running car, or in pressure build up and a leaky engine. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 That's weird, the only oil catch cans I've seen have all had little K&N filters on top of them. If you just ran both vents to that catch can and there is NO opening on it at all to vent, then you would have pressure build up very quickly in a turbo motor, as the boost pressure that escapes past the rings (blowby) would have no place to go... it will either force itself back up past the rings (I dont think so... but I"m not 100%) or it will force itself out thru 'the weakest links', namely, oil seals and gaskets. That picture does have me scratching my head though... maybe non vented ones are okay on N/A applications??? I seriously can't see how you'd get away with running a fully closed off catch can on a turbo motor... are you sure that thing has NO way for air to escape at all? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 At the very least, your oil dipstick is going to be popping out all the time.... Quote Link to comment Share on other sites More sharing options...
lilj Posted July 16, 2004 Share Posted July 16, 2004 Ok, thank you SOOO much for clearing that up. Thank god someone is willing to explain things to me =) Now I understand what you do and don't want. Also, As far as venting them.. you can just buy some of the breathers off of summit, that don't allow oil to leave it, just air. I believe they're like 7 bucks + shipping. Thanks again. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 okay now someone explain to ME why that catch can in the pic DOESN"T have a vent or filter on it?? Quote Link to comment Share on other sites More sharing options...
lilj Posted July 16, 2004 Share Posted July 16, 2004 No, I'm not sure it doesn't have a vent.. the link to the auction is under the picture.. you can look at like 30 diff pictures lol.. another, Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 okay I AM stumped... seriously... I did go looking for a pic or two of the catch cans I've seen... I was never really interested in using one so never thought to get the brand name or anything, but I remember it looking pretty much like that last pick you posted, just a shiny metal cylinder like that, with two hoses running into it, and a little K&N filter on top. I'm really stumped... if pressure is venting from the block and valve cover into this catch can, how does it escape after that? Wouldn't pressure just keep building up until it blew something out? Someone please clarify this for us..... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 I GOT IT!!! Those catch cans don't have a vent or filter on them because they are NOT meant to REPLACE the PCV system, but to run IN LINE with it!!! http://www.c-speedracing.com/howto/catchcan/catchcan.php basically you would keep the pcv system fully intact, but instead of running a hose from the crankcase vent directly to the PCV valve (and hence spew that oily air into your intake manifold), you would instead run the hose from the block vent to the catch can, and then from the catch can to the PCV valve. And THAT is definately a good idea... that way you still have vacuum in the block (at times) and you should still be smog legal, but you keep oil out of your intake. The catch cans I've seen with the filter on top are NOT meant to work with the PCV system, but are meant as a replacement for it. I WILL find a pic of one of these.... still looking Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 AH HAH!!! FOUND ONE!!! See I"m not on crack really! Think this link explains the hows and why's of this one as well: http://cjsupra.kendra.com/PCV-Can.html Notice that it says on that page "for racing use only" heheh... definately not smog legal Quote Link to comment Share on other sites More sharing options...
lilj Posted July 16, 2004 Share Posted July 16, 2004 Oh ok, nice link btw. The steel wool is also a very good idea hehe. I think thats exactly what I'll do then. So.. does the hose coming from the valve cover still go straight into the intake manifold? Isn't that just another way the oil would get into the intake? Or would we vent the valve cover? Or what? *getting less and less confused* only a matter of time now! haha Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 No you still would not want to vent the valve cover if you're going with the type of catch cans you posted the pics of... you would then have a vacuum leak, as your crankcase would still be routed to your PCV valve (passing thru the catch can), if you vented the valve cover to atmosphere, air could then be sucked in thru the valve cover, go thru the block, out the crank case vent, thru the catch can and pcv valve, and into your intake as unmetered air. Their either both hooked up, or their both vented to atmosphere, and neither should ever be blocked. I know that the oily air coming from the valve cover isn't nearly as bad as from the crankcase vent, but you do still see some smokey fumes exiting the valve cover vent now and then too. Doesn't the stock valve cover vent into the rubber boot before the turbo? I imagine that is bad, as you're going to get built up oil residue in the boot, which I'm sure isn't going to help it age any more gracefully. Maybe you're supposed to run two of those catch cans? I do know that there are baffles in the valve cover vent that I assume would keep too much oil from escaping from there though. Running the one catch can and leaving the PCV system intact, either way, is still a way better option than no catch can, and SHOULD be smog legal (of course it probably isn't). Quote Link to comment Share on other sites More sharing options...
lilj Posted July 16, 2004 Share Posted July 16, 2004 I will not have any emissions stuff anyway, so that doesn't matter to me! =) Welp, now I need to get my car back together so I can proceed with the catch can! I think I'm going to get one of those blue anodized (sp?) ones and make my engine bay look a tad more sexy! Thanks for all the information man, I think you pretty much cleared it all up for me (and probably everyone else.) JUNKYARD TIME! (in 6 hours) woot later, -jon Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted July 16, 2004 Share Posted July 16, 2004 -------------------------------------------------------------------------------- I GOT IT!!! Those catch cans don't have a vent or filter on them because they are NOT meant to REPLACE the PCV system, but to run IN LINE with it!!! There you go!! Quote Link to comment Share on other sites More sharing options...
zxtman Posted July 16, 2004 Share Posted July 16, 2004 What I did is run -10 hose from the crankcase and the valve cover to a breather tank (a catch can with a filter on top) and eliminated the pcv valve. Reasons being, I did not want the oily residue in the intake, I did not want to recycle hot air back through the intake, and the fact that the pcv valve does not allow evacuation of the crank case under boost when it is most needed. The -10 hose (5/8" ID) I used is large enough to allow the system to breathe/vent as needed. Of course, emissions are not an issue for me. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 What I did is run -10 hose from the crankcase and the valve cover to a breather tank (a catch can with a filter on top) and eliminated the pcv valve. Reasons being, I did not want the oily residue in the intake, I did not want to recycle hot air back through the intake, and the fact that the pcv valve does not[/b'] allow evacuation of the crank case under boost when it is most needed. The -10 hose (5/8" ID) I used is large enough to allow the system to breathe/vent as needed. Of course, emissions are not an issue for me. Agreed, this is why I would not want to run my PCV system intact at all, but would rather just vent everything, catch can or no. Just seems the better way to me. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted July 30, 2004 Share Posted July 30, 2004 Heres a couple of pics of my system. I just got it installed today. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 6, 2004 Share Posted August 6, 2004 Good info. I also decided to eliminate the PCV valve and vent the Block and Valve Cover to a vented catch can. All the logic sounds correct. This way, the crankcase will NEVER get pressurised, and no oil will get inhaled into the intake system. I ordered the Summit racing plastic catch can (breather tank) for $29 seems like its good enough for the job..and it comes in red, blue, or black. Emssions? Just tell them that the PCV is hidden under the intake behind the turbo...j/k. There is no emissions testing in my area. Does PCV affect driveability muchl? Just a reminder to the casual reader: dont forget to plug the PCV tap hole under the intake after you remove the PCV valve. Quote Link to comment Share on other sites More sharing options...
Owen Posted August 6, 2004 Share Posted August 6, 2004 -------------------------------------------------------------------------------- I GOT IT!!! Those catch cans don't have a vent or filter on them because they are NOT meant to REPLACE the PCV system' date=' but to run IN LINE with it!!! [/quote'] There you go!! AND...the quality-made catch cans should have baffles inside them. As the blow-by gasses pass through these baffles, the crap and sludge get trapped and accumulate at the bottom of the tank. No dumping the oil back into the engine when the tank is full! Theoretically, only clean air should make it back to the engine. Placement of the baffles and ports is important I bet, just like chambers in a muffler. Owen Quote Link to comment Share on other sites More sharing options...
Owen Posted August 6, 2004 Share Posted August 6, 2004 Agreed' date=' this is why I would not want to run my PCV system intact at all, but would rather just vent everything, catch can or no. Just seems the better way to me.[/quote'] I tried looking for it all over the net and couldnt find it. BUT, from what I've read, keeping the system intact is best for efficiency, not necessarily horsepower. This is only from memory so bear with me... An open PCV causes restriction within the block as air forced out of it has to overcome atmospheric pressure. On an NA engine, this is not as easy as it sounds. By connecting the PCV to the intake, the entire thing works as a system and as Jon mentioned, probably helps the rings seal better. Air being forced out of the block aids in pushing the pistons downward (which are being sucked downward at the same time by the vacuum via the PCV connected to the intake???). I have a filtered catch can and never have oil but always water in it. I plan "close" the system one day. Owen Quote Link to comment Share on other sites More sharing options...
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