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Turbo engine vent routing n42 intake manifold


elishallen

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So I just finished up swapping an 81 l28et into my 76 280z. Runs and drives but far from a smooth running car due to only having a downpipe haha. Using the n42 intake seemed like a good idea at first but I really didnt study up enough on it. Problem number one: the turbo blocks where the crankcase vent goes into the manifold. My solution to this problem was to just run it back into the J pipe, figured this was pretty much the same thing as before just without the little check valve and now it is behind the throttle. Problem number two: What to do with the other line I had running from the T connector, that was connected to the vent on the valve cover and airflow regulator, back to the j pipe. I ended up capping it off and didnt really see any change in performance. I guess my question here is how important is the airflow through everything? Does the air regulator actually need to be connected before and after the throttle?  I think this will be much easier to diagnose after I get an exhaust on the car, but for now its just running poorly. 

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: the turbo blocks where the crankcase vent goes into the manifold. My solution to this problem was to just run it back into the J pipe, figured this was pretty much the same thing as before just without the little check valve and now it is behind the throttle

Is the dipstick still in its hole?  Have you tried boost yet?  .

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Is the dipstick still in its hole?  Have you tried boost yet?  .

 

LOL!

 

Elishallen, just to be clear, you've connected the crank case vent directly to the J-pipe with no check valve? And by J-pipe, you're referring to the pipe that connects the turbo to the throttle body? Also, what do you mean by "behind the throttle?" Behind the throttle would be in the intake manifold, but if you have it connected to the J-pipe, that would up-stream, and therefore, ahead of the throttle.

 

To answer your question about airflow through everything, it is very important. The factory service manual does a very good job of explaining how it all works.

 

Nigel

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LOL!

 

Elishallen, just to be clear, you've connected the crank case vent directly to the J-pipe with no check valve? And by J-pipe, you're referring to the pipe that connects the turbo to the throttle body? Also, what do you mean by "behind the throttle?" Behind the throttle would be in the intake manifold, but if you have it connected to the J-pipe, that would up-stream, and therefore, ahead of the throttle.

 

To answer your question about airflow through everything, it is very important. The factory service manual does a very good job of explaining how it all works.

 

Nigel

Thanks, I take it that this is a very incorrect approach?

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Actually, the small area of the dip stick exposed to pressure probably isn't enough to lift it out.  I made a funny.  With the PCV hose connected to the J-pipe you'll be pressurizing the crankcase under boost.  You could fab in a PCV valve to get back to factory specs.

 

The AAR passes air across the throttle blade to let air past the throttle for higher idle speed.  But, the air is still metered by the AFM.  It's not clear if you left one of the three hoses from the T open or capped all of them.  The FSM's cover a lot but it's pretty spread out over the pages and there are some weak areas.  Like how the AAR is plumbed in the turbo/ECCS system (the pictures have no detail.  But, in general, the crankcase and intake system need to be completely sealed from outside air.  All air must enter through the AFM.  

 

No exhaust probably means no O2 sensor.  So you're in open-loop all the time.  With the N42 intake you've probably removed some of the vacuum control valves also.  They have an effect.

 

There's a lot of stuff needed to make the engine run right.  I don't have a turbo car but I like to keep up with what they need, for future reference.  Good luck.  Pictures are from 1983, 1981 might be simpler.

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How about an exhaust crankcase evacuation system. If your not using it as a daily car this is t a bad idea if you don't want fumes In the bay, basically run the lines to a 45 degree port to the exhaust after the oxygen sensor. It runs a slight vacuum and it's proven for other cars. I'm setting this system up for mine.

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Looks like you have everything running in to a cluster of an air-flow cross-road intersection.  Doesn't really fit the concept shown in Post #6 (see the arrows, fresh air and blow-by gas?). 

 

Does it run any differently?

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Barely any different. There was a bad startup but then it went back to normal (bad). So is the j pipe port for the blow by upper hose ONLY? I now see that the lower needs to be on the other side of the throttle. I am still missing where the air regulator is supposed to run to. Thanks for being so patient with me NewZed :P

 

Edit: after staring for another few minutes I noticed the lower blow by hose needs to be before the turbo. Thanks.

 

Edit again: Would it really change anything moving it before the turbo? It seems like that shouldnt matter, but im no expert by any means obviously. 

Edited by elishallen
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