Guest bastaad525 Posted July 9, 2004 Share Posted July 9, 2004 Here my take on this..... The catch can idea is a good idea. Diesels often use them and they work great just as long as you empty the catch can once and a while. Otherwise it will just overflow and defeat the purpose all together. As for hooking up your exhaust to your valve cover breather ports? Um NO. The exhaust will not suck the fumes/blow-by into the exhaust. If you've ever had an exhaust leak you will know that there is a "positive" pressure in the exhaust. If you hooked it up to your valve cover breather port you would pressurise your engine and you would have a lot of oil leaks fast. Even if you did have a check valve in the tube' date=' the pressure from the engine would not over come the pressure from the exhaust. Thats just IMOP! Since when does pulling your dipstick cause a vacuum leak? The air that is in the block doesnt not need to be metered since it does not enter the cylinders with the A/F ratio. Maybe I am just misunderstand what is being said here? Guy[/quote'] 80lt1, I don't think its a good idea to hookup the port to the exhaust either but don't think that the exhaust can't suck . If you have a leaking exhaust you can feel it blowing when you are idling. But when the exhaust gas speed goes up you can create a venturi efect and this wil creat a low pressure. This is why a leaking exhaust header gasket can throw of your O2 sensor readings. At higher velocities it will start pulling in air. EXACTLY, once the exhaust gets moving at speed it WILL create a suction effect. And anyways routing your valve and crankcase vents to your exhuast using a one way valve was not MY idea, there are kits being sold to do exactly this by popular hot rod parts places. I don't make this stuff up, guys And pulling your dipstick or opening the oil cap on the valve cover will definately cause a vacuum leak if you have your PCV system intact. Car will barely idle like this. jmortensen - come to think of it I believe you're right, I didn't remember exactly what I had heard as to why the vacuum pump evacuating the crankcase increased power... but yeah if I remember it did have to do with helping the rings seal better, that sounds familiar. All I know is it WAS proven to increase hp (though I don't remember how much it was, I do remember that it wasn't by much... something drag race guys might do to get that last tenth). But any increase in hp means the motor must be running better, right? A friend of mine who races his Z did say he got something like 20hp to the wheels from using one of the ones that routes the vents to the exhaust... I scoffed at him but... he does have a nice Z and I haven't known the guy to be a BS'er in the past. Quote Link to comment Share on other sites More sharing options...
Guest stonehenge69 Posted July 10, 2004 Share Posted July 10, 2004 This is what I did. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted July 10, 2004 Share Posted July 10, 2004 Nice set up!! Quote Link to comment Share on other sites More sharing options...
80LS1T Posted July 12, 2004 Share Posted July 12, 2004 Does pulling the dipstick tube or removing the oil cap on a non MAF system create a vacuum leak? I just have never heard of this and now Im curious! Guy Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 12, 2004 Share Posted July 12, 2004 See now this setup might be kinda confusing for some... but you see similiar stuff a lot on carbed vehicles, as was said earlier in the post you can really get away with it with carbs, tune around it. (for anyone who didn't look, he's got his crankcase vent routed into his carb intake manifolds, but an open valve cover vent). I imagine you could do the same thing in an EFI Z, but I wouldn't... Really better to leave them both open, have them both routed stock, or route them both to a catch can. Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 12, 2004 Share Posted July 12, 2004 Does pulling the dipstick tube or removing the oil cap on a non MAF system create a vacuum leak? I just have never heard of this and now Im curious! If it's plumbed in a similar manner to the stock EFI, then yes it will cause a vacuum leak. On a speed-density type EFI it doesn't matter, since the system just measures manifold pressure and doesn't care where the air came from. Quote Link to comment Share on other sites More sharing options...
lilj Posted July 14, 2004 Share Posted July 14, 2004 so in term i would have a better a/f ratio if i run a catch can off the rocker cover, and block off the pcv vavle. and it looks smarter damn, late and night i love these kind of statements.. so simple and to the point. everything else confuses the living hell out of me. i'm pretty much confused on exactly what i should do.. i just ordered a non-egr intake mani, and i'd like to have some kind of idea what works best. what i can tell from reading through everything is that there are three options: a) block the pcv off and run a catch can from the valve cover.. buy a baffled breather or one that doesn't allow oil (just air) to pass through. c) run the stock pcv setup and have oil and other deposits put into your intake tract. a - but, is this true? run a catch can off of the valve cover and just block off the part coming out of the block? if so, is the piece coming out of the block just threaded in? ie. can i just undo it and replace it with a plug? b - hell of a lot cheaper than a catch can. c - is there a place to hook up the pcv system on the non-egr manifolds? (i'd assume so, but i don't have it in my possession yet.) boy, i've gotten myself into a mess here! =) thanks, -jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 14, 2004 Share Posted July 14, 2004 Again, either just run both the crankcase and valve cover vents open with a filter, or, vent them into a catch can. Either will work fine, catch can will be cleaner. Neither would have any noticeable effect on performance. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted July 14, 2004 Share Posted July 14, 2004 My plan is to run everything into a catch can and then to the front of the turbo intake pipe behind the MAF. I made mine out of metal so it souldn't be to hard to weld in some new fittings. This would still serve the purpase of venting everything. While under full power it will pull a vacuum from the crankcase which has been proven to help make power. This is a small amount of power but, I'll take anything I can get that if basically free power. Quote Link to comment Share on other sites More sharing options...
jeffp Posted July 16, 2004 Share Posted July 16, 2004 I have just bought the same can you did Cody (the guy is a flake, and gouges on the shipping) But the reason I am interewsted in the catch can is that my engine appears to be using oil. I have noted this ever since the engine has been rebuilt. I spoke to Davr Robello regarding the ptroblem and he suggested it was sucking oil under vacuum, from boost to vacuum type situation. First thing, the stock nissan *# uses the flapper type AFM, so if you open up the top of the valve cover, you create a big vacuum leak (AFTER the AFM) so the flapper closes and kills the fuel for the most part. If you open up the PCV valve, again you create a big vacuum leak @ the intake after the T/B this may or may not kill the engine, but you will have a very lean condition. The idea behind the PCV is to REMOVE leaked gases past the rings when the cylinder fires. Do this turn your engine over and you can hear the hissing, that is ring blowby, and that is not anywhere near the pressure that is produced when the mixture fires off. You get spent fuel and combustion deposits past the rings, and that builds up on the block, and engine components, not to mention in the oil. The valve cover breather, again is designed to remove any air pressure from within the engine, VIA the intake after the AFM in the rubber boot, pipe however you like to call it. Here is the problem with the turbo cars. The turbo experiences a much wider range of potiential pressure and vacuum in the engine. THE PCV is critical that it is operating correctly, or you will pressureize the engine with the boost pressure. YOU NEED THE PCV! in a turbo application. But what I think is happening in my case is that I am sucking oil from either the valvecover or the PCV and it is being spent in the combustion cycle, causing excessive oil consumption. I know I am getting oil from somewhere because when I took off the intake, I could see the oil deposits on the intake ports, before the valve and all that neat stuff. I need to stop this from happening. The catch can is the answer. Bottom line is that EVERY engine needs the PCV valve to clean out the crap that is developed from ring blowby. My recommendation is to filter the valve cover opening, run the PCV into a catch can and leave it hooked up. I will note one thing tho, with all of the filters I have seen on the L series engines, there is ALWAYS some oil residue by the filter on the valve cover, that tells me you should use the catch can, or just clean up the oil on a regular basis. Quote Link to comment Share on other sites More sharing options...
Guest stonehenge69 Posted July 16, 2004 Share Posted July 16, 2004 PCV System PVC Valve L28 Engine Pressure Quote Link to comment Share on other sites More sharing options...
jeffp Posted July 16, 2004 Share Posted July 16, 2004 on your second link, the picture explains it all. Under pressure, the valve closes, but in the L engine configuration, the blowby pressure then goes to the valve cover hole and down into the intake to be recirculated. there is the oil problem, it gets sucked up into the intake and clogges up everything. Dirty dirty oil LOL. Quote Link to comment Share on other sites More sharing options...
Guest stonehenge69 Posted July 16, 2004 Share Posted July 16, 2004 Jeff, how do you plan on plumbing your catch tank? and what is the actual size of the tank. It's hard to tell in the add. Quote Link to comment Share on other sites More sharing options...
Guest butlersZ Posted July 16, 2004 Share Posted July 16, 2004 Now not to go off the topic or anything, but I heard from somewhere that the PCV system helps keep combustion deposits and carbon buildup way down by somewhat lubricating, if thats what you want to call it, the piston tops and cylinder walls as well as the valves and the combustion chambers in the head? If true, that would be an obvious benefit of the PCV system. I have also heard about venting the valve cover breather and crankcase to the exhuast to create a vacuum or negative pressure in the crankcase. A hardcore racer friend of mine that did run the breathers into the exhuast actually has before and after dyno runs proving that his car gained 13HP at the rear wheels after the mod. I will see if I can get pics of his dynographs and upload them. I personally have always ran the breathers to a catch can, a sort of nuetral point I guess. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted July 16, 2004 Share Posted July 16, 2004 the guy is a flake, and gouges on the shipping Don't know about the flake part but, the shipping was crazy. Not quite as bad coming to me but, you couldn't be to far from him. It was still the best price I found. Hopefully it's not the size of a small match box. I should be gettingmine early next week. Who knows when I'll get a chance to get it all mounted right and tested me to see if I can find any real results. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 I thought if you just ran an open filter on the crankcase vent that blowby gasses would still escape no problem, and pressure in the crankcase from boost would not be an issue. Quote Link to comment Share on other sites More sharing options...
lilj Posted July 16, 2004 Share Posted July 16, 2004 All I know is that I'm going to buy a catch can and run a hose from both places (valve cover and block). Its the only way I can see keeping the pressure *(wrong, now i know)* and what not how it should be. but i could be wrong, that wouldn't be anything new... -Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 A catch can shouldn't allow any pressure either. Every oil catch can I've seen for this purpose is open with a little breather filter on top. I think the ONLY purposes of the catchcan are a) to keep oil from building up on your block and valve cover(s), and possibly to 'save' oil... as I know some people occasionally take the oil from their catch cans and dump it back in the engine. Otherwise, as I understand it, there is NO difference in running a catch can and just running filters on the two vents. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 This topic getting uncharacteristically confusing for a HybridZ topic.... Quote Link to comment Share on other sites More sharing options...
lilj Posted July 16, 2004 Share Posted July 16, 2004 So then how would you keep it pressurized without just using the stock locations? From what I understood you WANT it to stay pressurized. I am very confused. =/ breather? where? http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7910896765&category=46098 Quote Link to comment Share on other sites More sharing options...
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