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Fi Crankcase Pressure

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Old 11-29-2006, 05:38 AM
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mgtibbetts
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Default Fi Crankcase Pressure

Has anyone read the 350Z Q&A article in the new issue of Nissan Sport yet?
Part of the article says:
"While the VQ series engine is great at making power and torque and is very reliable, when FI is applied to it, the PCV system may not handle the increased crankcase pressure. After speaking with Nissan North America about this concern, I learned that there may not be sufficient flow through the PCV valve to handle the increase in crankcase pressure. What was recommended to me was to use a PCV valve with Nissan part number 11810-F0511. This is a valve that was used in the older L-series of engine in the original Z car lineup....This will help to make sure the pressure in the crankcase stays low."

Also says you will need to use a larger threaded fitting to adapt the valve to fit.

Has anyone else heard of this?
Sounds pretty interesting. I'm not a mechanic but I wonder if that is what could be causing bent rods and such.
Old 11-29-2006, 06:48 AM
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Q45tech
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Always a good idea to CONTINUOUSLY measure the WOT crankcase psi to watch the rings as the blowby increases and increases and increases with each stress cycle.
Old 11-29-2006, 06:52 AM
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redline350ZZ
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Originally Posted by Q45tech
Always a good idea to CONTINUOUSLY measure the WOT crankcase psi to watch the rings as the blowby increases and increases and increases with each stress cycle.

I just drilled holes in the case to help equalize the pressure.
Old 11-29-2006, 07:22 AM
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meatbag
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Originally Posted by redline350ZZ
I just drilled holes in the case to help equalize the pressure.
Old 11-29-2006, 08:41 AM
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redline350ZZ
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Originally Posted by meatbag

I kid, I kid. Dear god if someone had taken that seriously and drilled holes in their block.
Old 11-29-2006, 09:39 AM
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thawk408
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While I was putting my engine back in after the TT install one of the engine straps broke my PCV valve so I used one my friend had laying around from an older Q45. I wounder if this one is bigger then the Q45 one.
Old 11-29-2006, 09:47 AM
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Nic@CiNcity
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I'd like to hear more on this. I wonder what some of the big name shops are doing?
Old 11-29-2006, 11:06 AM
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THE TECH
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+1
Old 05-14-2013, 03:11 PM
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bmccann101
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necrobump..

i have a built engine w a single pt6266.. im having issues w what i believe is crankcase pressure.. i get oil leaks out of my dipstick ( sounds like the clap lol) when i get into high boost.. and the oil burns and smells ..

initially we found that the dipstick seal was compromised and oil was overfilled..

but i think im still getting some smell and leak when i get on it and bet up into real boost.. and my pump gas map peaks out at like 24 psi.

anything to add on this? Hoping someone will pick this up in the todays post section..

Last edited by bmccann101; 05-14-2013 at 03:15 PM.
Old 05-14-2013, 03:41 PM
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Colombo
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i thought most in the FI community were drilling out the PCV valve and driver side valve cover and either A. routing them both to a catch can with a breather or drilling out both PCV valve and driver side valve cover and just installing large breathers on both? my motor let go before i could test either options. more info would be great. ive always felt that this topic was 1 that is left unclear alot. most threads started on this leave no "this is the way to do it correctly"
Old 05-14-2013, 03:43 PM
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bmccann101
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I concur..
I dont really want to vent to atmosphere unless its heading out the back of my car..smells bad enuff already Lol. so i steered away from a vented catch can..i actually dont even have a catch can yet..i ran out of time and room..
Old 05-14-2013, 03:55 PM
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Colombo
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Originally Posted by bmccann101
I concur..
I dont really want to vent to atmosphere unless its heading out the back of my car..smells bad enuff already Lol. so i steered away from a vented catch can..i actually dont even have a catch can yet..i ran out of time and room..
agreed! i tried few different setups right before my motor let go but it already had odd signs of blow by so i couldnt gauge how well any of them worked. but far before when i first did my blower my catch can was fairly simple. from lower intake manifold to catch can- catch can to un molested PCV valve and my driver side valve cover to atmosphere. but the more research i did the more confused i got. it made it seem as thought my way was only causing more restriction in the system and bairly catching vapor at best.
Old 05-14-2013, 08:25 PM
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Resmarted
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Originally Posted by bmccann101
I concur..
I dont really want to vent to atmosphere unless its heading out the back of my car..smells bad enuff already Lol. so i steered away from a vented catch can..i actually dont even have a catch can yet..i ran out of time and room..
Ill take a moment and compliment how gorgeous your rear end is... on your car...
Saw some pics of it, and it really came together AWESOME so cheers to that!

BUT back on topic.

All you need to do is run lines from your vents (IE the driver side rear, and the drilled out PCV) and use a special kind of check valve. I believe the valve my friend used on his car is for catalytic converters... I had it favorited on my other computer, but that thing died when I spilled water on it (sad day).
Take a look around the supra forums, they typically are the ones who do it. I personally kind of like the smell of oil, and don't mind venting to atmosphere.
Ill pm you with a thread that shows the kind of fitting you put in your exhaust. Real simple and easy to do, works great.
Old 05-14-2013, 08:34 PM
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bmccann101
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Awesome..thanks man.
Old 05-17-2013, 06:07 AM
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binder
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Ya, they make those weld in vents that go in the exhaust.

You are probably still pushing oil out of the dipstick. I would vent the valve covers asap if it was me before your front seal blows out of the car like mine did when I had a kink in the vent hoses. I always have that smell from my breathers and I do get some oil residue coming out of my dipstick even with proper venting. The seal on the dipstick just isn't that great.
Old 05-17-2013, 07:43 AM
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mw9
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Originally Posted by Resmarted
Ill take a moment and compliment how gorgeous your rear end is... on your car...
Saw some pics of it, and it really came together AWESOME so cheers to that!

BUT back on topic.

All you need to do is run lines from your vents (IE the driver side rear, and the drilled out PCV) and use a special kind of check valve. I believe the valve my friend used on his car is for catalytic converters... I had it favorited on my other computer, but that thing died when I spilled water on it (sad day).
Take a look around the supra forums, they typically are the ones who do it. I personally kind of like the smell of oil, and don't mind venting to atmosphere.
Ill pm you with a thread that shows the kind of fitting you put in your exhaust. Real simple and easy to do, works great.
Could you also PM me that thread
Old 05-19-2013, 05:49 PM
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binder
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Originally Posted by mw9
Could you also PM me that thread

http://vibrantperformance.com/2012_c...logue_pg64.pdf

http://www.sparktecmotorsports.com/v...tm_content=pla
Old 05-20-2013, 08:43 AM
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Interesting, never seen it ran to the exhaust
Old 05-20-2013, 10:06 AM
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djamps
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Doubt PCV valve would cause a bent rod. But who knows... I've been on my stock PCV system for several years now at 10lbs boost. But my engine has good compression and very little blow by. For tired engines or big boost, PCV system hacks are mandatory.
Old 05-20-2013, 10:11 AM
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Resmarted
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Originally Posted by djamps
Doubt PCV valve would cause a bent rod. But who knows... I've been on my stock PCV system for several years now at 10lbs boost. But my engine has good compression and very little blow by. For tired engines or big boost, PCV system hacks are mandatory.
Well although I'm jealous your car runs very well, have you ever opened up your plenum? Lol you won't think your pcv is so great when you see that yucky *** mess. Mine took some good scrubbing with a bunch of carb cleaner.

Besides that, I think there is some kind of vapor that actually directly robs hp, can't remember what the name is but I'm pretty sure it comes from the crank case. Someone correct me if they know.


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