Installing a catch can - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

nsn240 · 10-30-2005, 08:14 PM

Ok, I've searched and searched on this...

Installing a greddy catch can... one hose comes off the t-fitting and goes to the can, and the other goes back to the intake pipe? Looking at one picture, theres only a hose leading to the can and not coming back, is that for any reason...

any help would be great. thanks

Indolent · 10-30-2005, 08:17 PM

intake pipe

go240 · 10-30-2005, 08:19 PM

Quote:

Originally Posted by Indolent

intake pipe

beat me to it

nsn240 · 10-30-2005, 08:38 PM

so would it hurt anything if i didnt return a line to the intake? keeps everything out... i've also been reading about people putting steel wool in to 'catch' the oil, the newer style (wouldnt have ordered had i known this) is a solid can... putting the wool in isnt an option, unless i poke it through the little fitting holes - so not connecting the hose back to the intake pipe would prevent anything from going through the can and back into the engine

pics here:
http://www.club240.com/forums/showth...threadid=27830

tt99ol · 10-31-2005, 05:39 PM

have you driven your car since youve installed that catch can, with that one fitting open? If you have then you would have noticed the increased spool up time, vacuum runs through that line via the pcv system, if it isnt connected then you will run slightly leaner than normal, it is basically a big vacuum leak, plus when you are at higher rpms the pcv closes and the hose leading to the intake now removes pressure from the crankcase along with blowby gasses. Pressure in the crankcase is bad. Basically what im saying is connect the catch can properly. Oh yeah, even though the nipples on the can are right next to each other doesnt mean they are both open right there, the inlet has a turndown tube i believe so that no fluids go into the intake.
-Phil

DJPimpFlex · 10-31-2005, 06:14 PM

Quote:

Originally Posted by tt99ol

have you driven your car since youve installed that catch can, with that one fitting open? If you have then you would have noticed the increased spool up time, vacuum runs through that line via the pcv system, if it isnt connected then you will run slightly leaner than normal, it is basically a big vacuum leak, plus when you are at higher rpms the pcv closes and the hose leading to the intake now removes pressure from the crankcase along with blowby gasses. Pressure in the crankcase is bad. Basically what im saying is connect the catch can properly. Oh yeah, even though the nipples on the can are right next to each other doesnt mean they are both open right there, the inlet has a turndown tube i believe so that no fluids go into the intake.
-Phil

I dont get why you would run leaner. The air thats comming from the PCV has already been meatered at the MAF so removing that air source would make you run richer. (correct me if I'm wrong). Also I dont think theres a valve that opens and closes in the valve cover. I just took it off and replaced the seal, thats how I know. Under boost it will get sucked out, but it doesnt NEED to be as far as I know. The pressure caused by the pistons going back down and pressure comming back up the front cover will all get releved through the valve cover and then move to the catch can naturally. I dont see how removing air from the intake is going to make more pressure in the crankcase. I run mine open and havent noticed any problems so far. More input please. I'm not an expret, but this is how it makes sense to me. Also the ECU will compinsate for the "leak" after a few days I believe.

tt99ol · 11-01-2005, 04:22 PM

Quote:

Originally Posted by DJPimpFlex

I dont get why you would run leaner. The air thats comming from the PCV has already been meatered at the MAF so removing that air source would make you run richer. (correct me if I'm wrong). Also I dont think theres a valve that opens and closes in the valve cover. I just took it off and replaced the seal, thats how I know. Under boost it will get sucked out, but it doesnt NEED to be as far as I know. The pressure caused by the pistons going back down and pressure comming back up the front cover will all get releved through the valve cover and then move to the catch can naturally. I dont see how removing air from the intake is going to make more pressure in the crankcase. I run mine open and havent noticed any problems so far. More input please. I'm not an expret, but this is how it makes sense to me. Also the ECU will compinsate for the "leak" after a few days I believe.

The pcv pulls fresh air from the intake and uses it to suck out air from the crankcase and into the intake manifold, if you leave this hose unattatched you are actually pulling in air which is now being un-metered, this causes a lean situation i believe. The pcv valve is the valve which opens and closes in the valve cover, it is open under vacuum but once you boost it closes so that the crankcase will not be pressurized which is where the breather side comes to the rescue and now relieves the pressure. The pressure will relieve itself on its own but instead of it being drawn out the piston and crank movement have to force it out causing excessive wear, and possibly oil consumption. Basically the crankcase now becomes a low pressure compressor. Honestly though im not sure if the computer does compensate for the leak, i would think it would via the air/feul reading of the O2 sensor. You say you havent noticed any problems yet though, not even more lag? I tried to put a breather filter on (which would be the same situation) and i noticed a crappy idle, and more lag right away, thats when i learned about all of this and put my breather hose back on. i believe ive answered all of your questions but if anything is unclear just ask.
-Phil

nsn240 · 11-01-2005, 07:05 PM

i believe tt99ol is right... the ebay seller sent me the wrong thing, and i have to wait to return it... Put very very simply: running it back to the intake completes the vaccuum the car needs to function its best

DJPimpFlex · 11-03-2005, 01:56 AM

I suspose thats right. I gotta change my whole set up again. But I didnt notice any difference in performance at all. Idle was the same, spool up the same and oil consumption was the same. to be fair I've only driven about 10 miles with this set up. I researched it a bit on the internet and found this. Maybe this can help.

http://cjsupra.kendra.com/PCV-Can.html

I know that not all info in the internet is awlays right, but after reading this it kinda makes sense. Its a toss up and I dont think that there will be determental consequences either way though.

10-30-2005, 08:14 PM	#1
nsn240 Zilvia Addict Join Date: Aug 2005 Location: pa Posts: 642 Trader Rating: (1) Feedback Score: 1 reviews	Installing a catch can Ok, I've searched and searched on this... Installing a greddy catch can... one hose comes off the t-fitting and goes to the can, and the other goes back to the intake pipe? Looking at one picture, theres only a hose leading to the can and not coming back, is that for any reason... any help would be great. thanks

10-30-2005, 08:38 PM	#4
nsn240 Zilvia Addict Join Date: Aug 2005 Location: pa Posts: 642 Trader Rating: (1) Feedback Score: 1 reviews	so would it hurt anything if i didnt return a line to the intake? keeps everything out... i've also been reading about people putting steel wool in to 'catch' the oil, the newer style (wouldnt have ordered had i known this) is a solid can... putting the wool in isnt an option, unless i poke it through the little fitting holes - so not connecting the hose back to the intake pipe would prevent anything from going through the can and back into the engine pics here: http://www.club240.com/forums/showth...threadid=27830 Last edited by nsn240; 10-31-2005 at 10:13 AM..

11-03-2005, 01:56 AM	#9
DJPimpFlex Post Whore! Join Date: Jan 2004 Location: Rohnert Park, CA Age: 39 Posts: 6,158 Trader Rating: (115) Rides Gallery: DJPimpFlex Feedback Score: 115 reviews	I suspose thats right. I gotta change my whole set up again. But I didnt notice any difference in performance at all. Idle was the same, spool up the same and oil consumption was the same. to be fair I've only driven about 10 miles with this set up. I researched it a bit on the internet and found this. Maybe this can help. http://cjsupra.kendra.com/PCV-Can.html I know that not all info in the internet is awlays right, but after reading this it kinda makes sense. Its a toss up and I dont think that there will be determental consequences either way though. __________________

10-30-2005, 08:17 PM	#2
Indolent Zilvia FREAK! Join Date: Jun 2005 Location: So. Cal, Riverside Area Posts: 1,110 Trader Rating: (3) Feedback Score: 3 reviews	intake pipe

10-31-2005, 05:39 PM	#5
tt99ol Zilvia Addict Join Date: Jan 2005 Location: quartz hill CA Age: 38 Posts: 644 Trader Rating: (8) Feedback Score: 8 reviews	have you driven your car since youve installed that catch can, with that one fitting open? If you have then you would have noticed the increased spool up time, vacuum runs through that line via the pcv system, if it isnt connected then you will run slightly leaner than normal, it is basically a big vacuum leak, plus when you are at higher rpms the pcv closes and the hose leading to the intake now removes pressure from the crankcase along with blowby gasses. Pressure in the crankcase is bad. Basically what im saying is connect the catch can properly. Oh yeah, even though the nipples on the can are right next to each other doesnt mean they are both open right there, the inlet has a turndown tube i believe so that no fluids go into the intake. -Phil

11-01-2005, 07:05 PM	#8
nsn240 Zilvia Addict Join Date: Aug 2005 Location: pa Posts: 642 Trader Rating: (1) Feedback Score: 1 reviews	i believe tt99ol is right... the ebay seller sent me the wrong thing, and i have to wait to return it... Put very very simply: running it back to the intake completes the vaccuum the car needs to function its best