onephatz Posted May 6, 2004 Share Posted May 6, 2004 I just got my 1g dsm bov installed but if I try to have it vent to the atmosphere the vacume from the intake opens it at ide and causes a lope at idle, but it purges fine when I'm doing a full throttle run. so.... I tryed to vent back to before the turbo by teeing into the line that feeds air into the crankcase vent system. I thought it would work(and it does) but now when I let off the gas after a hard pull I get a nice blue smoke screen behind me when the extra boost shoves the crank case oil particles into the intake. question: can I elminate the crank case circulation system and just put a filter on the valve cover to allow oil expansion space or do you have to have it circulate like it is. also is what I have off a dsm a Blow off valve or a Bypass valve? any ideas? jesse p.s. all i can say is HOLY COW 14psi ! dang this is fun Quote Link to comment Share on other sites More sharing options...
Jersey Posted May 7, 2004 Share Posted May 7, 2004 Hey Jesse. If you're going to recirculate the BOV (Blow Off Valve), you should pipe it in between the AFM and turbo. The reason for your blue smoke is most likely because when it "blows off", it's putting pressure back into the crankcase. I wouldn't eliminate the line from the crankcase to the intake. It burns the nasty vapors coming out of your bottom end and it doesn't hurt performance leaving it hooked up. I you want to try and leave the BOV open to atmosphere but loose the loping, try crushing it in a vise a little bit to create more spring pressure. That should hold the valve closed at idle. Quote Link to comment Share on other sites More sharing options...
fl327 Posted May 7, 2004 Share Posted May 7, 2004 Hey Jesse. If you're going to recirculate the BOV (Blow Off Valve), you should pipe it in between the AFM and turbo. The reason for your blue smoke is most likely because when it "blows off", it's putting pressure back into the crankcase. I wouldn't eliminate the line from the crankcase to the intake. It burns the nasty vapors coming out of your bottom end and it doesn't hurt performance leaving it hooked up. I you want to try and leave the BOV open to atmosphere but loose the loping, try crushing it in a vise a little bit to create more spring pressure. That should hold the valve closed at idle. Oh what, youre not supposed to vent the bov into the crankcase? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted May 7, 2004 Share Posted May 7, 2004 You can T'ed the BOV back to crankcase vent. hose since it goes back in front of the turbo Quote Link to comment Share on other sites More sharing options...
Jersey Posted May 7, 2004 Share Posted May 7, 2004 The crankcase vent goes from the side of the block to the PVC valve which is screwed into the intake. I think you're thinking of the valve cover vent hose which T's into the boot between the AFM and turbo Yo. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted May 7, 2004 Share Posted May 7, 2004 I think the main problem is the pipe from the exit of the DSM valve is too small, so you are creating pressure in the crankcase. My intake pipe between my MAF and the turbo is large enough to dump the boost without a rise in pressure, so even though my crankcase vent is tied in to the same place, there is no flow back into the crankcase on a boost dump. In other words, don't "T" it in, plumb it to the intake by itself. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted May 7, 2004 Share Posted May 7, 2004 The crankcase vent goes from the side of the block to the PVC valve which is screwed into the intake. I think you're thinking of the valve cover vent hose which T's into the boot between the AFM and turbo Yo. You're correct, I'm a dummy Quote Link to comment Share on other sites More sharing options...
Jersey Posted May 7, 2004 Share Posted May 7, 2004 It's just friday Yo Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted May 9, 2004 Share Posted May 9, 2004 I used to have my BOV vent tee'd into the hose that ran from the valve cover vent to the afm-to-turbo rubber boot. I had no apparent problems with this. I never liked the way the valve cover and crank breathers were plumbed into the intake though as oil does find it's way into the intake this way, which, among other things, can cause detonation... something I didnt want to worry about in a turbo motor. So I just put the little K&N filters on the valve cover and crankcase breathers, and then ran a new hose from the BOV, directly in to where the valve cover breather vented to on the AFM-turbo boot. However, I dont think this is the perfect solution either, as the opening on the boot is quite a bit smaller than the BOV's opening... so there is the possibility that pressure might be building up there when the BOV tries to vent that pressure into the much smaller hole. Seems to work fine but one day I plan on modifying this somehow. Quote Link to comment Share on other sites More sharing options...
onephatz Posted May 10, 2004 Author Share Posted May 10, 2004 I used to have my BOV vent tee'd into the hose that ran from the valve cover vent to the afm-to-turbo rubber boot. I had no apparent problems with this. I never liked the way the valve cover and crank breathers were plumbed into the intake though as oil does find it's way into the intake this way, which, among other things, can cause detonation... something I didnt want to worry about in a turbo motor. So I just put the little K&N filters on the valve cover and crankcase breathers, and then ran a new hose from the BOV, directly in to where the valve cover breather vented to on the AFM-turbo boot. However, I dont think this is the perfect solution either, as the opening on the boot is quite a bit smaller than the BOV's opening... so there is the possibility that pressure might be building up there when the BOV tries to vent that pressure into the much smaller hole. Seems to work fine but one day I plan on modifying this somehow. yea this is how it is right now. I talked to a guy who said it wasn't really bad not to have a crankcase vent system but it does help clean out some of the stuff that can work past the rings. also helps expel water that can build up in the crankcase. it works well enough at the moment to give enough relief to the turbo not to cause compressor stall. good news though, I have located an actual (used)greddy blow off valve (not a bypass valve) for $50 bucks. after I get it installed I will reinstall the crankcase vent system. then I can just dump to the atmoshpere and not care . got to say that 14psi in a 2600lb car really rocks. I had a good time with a fellow last night who had a 72 chevelle(sp?) and was running mid twelves and I was running a little ahead of him(better hook up). man I'm excited! gettin my car dynoed this next weekend. I'll let ya all know what she puts down. later jesse Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted May 10, 2004 Share Posted May 10, 2004 Even with a true BOV you MAY run into problems with rich running under vacuum conditions and between shifts. So running w/o a proper PCV system is detrimental? I always figured just running the open filters wouldn't hurt anything. Water evaporates out... you can see a little smoke coming from the filters on mine as the car warms up... I'm pretty sure blowby finds it's way out w/o problems. Quote Link to comment Share on other sites More sharing options...
onephatz Posted May 10, 2004 Author Share Posted May 10, 2004 So running w/o a proper PCV system is detrimental? I always figured just running the open filters wouldn't hurt anything. Water evaporates out... you can see a little smoke coming from the filters on mine as the car warms up... I'm pretty sure blowby finds it's way out w/o problems. the way it was explained to me was that what can happen(usually during cold seasons) is that you will experience what he referred to as "the milk shake syndrome" where the water in the crank case will mix with oil cause bearing problems. he said though during dry seasons or warm seasons it's not as much of a concern but during the cold wet seasons water can condense more inside the motor a little more. so.......don't know what will really happen, I have seen that happen in an automatic transmission before though. anyway jesse Quote Link to comment Share on other sites More sharing options...
280zinsanity Posted May 13, 2004 Share Posted May 13, 2004 werd... Quote Link to comment Share on other sites More sharing options...
280zinsanity Posted May 13, 2004 Share Posted May 13, 2004 werd... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 20, 2004 Share Posted May 20, 2004 Crankcase vent open to atmosphere? Do that on the "airtight" EFI system and you have created a vaccuum leak. Any air that has been measured by the AFM must leave through the exhaust or your mixtures wont be correct. Any opening in the motor (valve cover vent or blow off to atmosphere) will cause mixture calculation errors. Pull your dipstick or loosen your oil cap on an airtight Z motor that is tuned properly and the engine will stumble. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted May 20, 2004 Share Posted May 20, 2004 cygnus, not if both your crankcase and valve cover vents are open to atmosphere. the problem comes when you vent one and not the other... they run in a loop that connects to the intake. If you vent both and obviously block off the points on the intake that they vented to, you should be fine... no vacuum leaks. I run like this and so do many many other people. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted May 20, 2004 Share Posted May 20, 2004 Right, I run with both vented to atmosphere and no problems with stock EFI or new setup. Quote Link to comment Share on other sites More sharing options...
spork Posted May 20, 2004 Share Posted May 20, 2004 I've recently installed and sds management system in my car(83 280zxt) and re-did all the pipes to my intercooler and turbo and intake and eliminated the line from the valve cover to the intake but kept the line from the intake to the crankcase. I just put a little filter on the valve cover. Are you guys saying that I need to vent the crankcase too? I would think that this wouldn't be a problem, but if it is, can someone explain why? Quote Link to comment Share on other sites More sharing options...
mobythevan Posted May 20, 2004 Share Posted May 20, 2004 With your setup you have an open hole in your intake now, just sucking air as it pleases from atmoshpere to your intake. Your valve cover takes in air from atmo, and then under vacuum it goes through the block vent into your intake. On the stock setup there is a check valve at the intake for the block vent pipe, that way you don't lose boost back into the block. Quote Link to comment Share on other sites More sharing options...
spork Posted May 20, 2004 Share Posted May 20, 2004 I don't have any open spots on my intake as I made an entirely new intake tube...maybe I wasn't clear enough on that. I have un-interupted piping from the intake filter up front all the way to the fresh air inlet of the turbo. The hose from the check valve on the underside of the intake to the block/crankcase vent is still in place. James Quote Link to comment Share on other sites More sharing options...
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